Theatre of noise 
Configuring a computer for gallery use
This article will explain how to set up a Windows 11 Pro computer for unattended operation, for example when running a gallery installation or kiosk. This article is a companion to Remote Computer Access. These articles do not assume that you are an expert, but do require you to be familiar with using Windows. If required, you can find more detailed tutorials online. My aim here is to be concise and precise since I have not yet found an overview of this kind. There are four main tasks: configure Windows for unattended use, create an account for remote access, set up automatic login, and configure Wi-Fi. A. Windows configuration Many of the tasks can be accomplished through Settings, which can be accessed several ways. For example, you can right-click the desktop and choose "Personalise". Or click on the gear icon that might appear on your toolbar or Windows menu. 1. System settings Click "System" in the left panel. a) Ensure your computer has a memorable name. This will be displayed at the top of the panel, but if you need to change it, scroll all the way to the bottom and choose "About". b) Choose "Sound" and ensure the default devices are correct. c) Choose "Notifications" and turn off everything. d) Choose "Power" and then "Screen, sleep, & hibernation time-outs." Set all these to "Never". Ensure "Energy saver" is "Off" because you don't want random parts of the computer falling asleep. 2. Personalisation settings Click "Personalisation" in the left panel. a) "Background" allows you to use a distinctive desktop image. For an installation I customise the desktop to display any required instructions or to highlight the icons that run the show. b) "Themes" is useful for two purposes. First, you can set a larger mouse cursor that's easier to find on the screen. This is especially useful under less than perfect viewing conditions. c) Second, click "Sounds" in order to see the following dialogue. Set the "Sound Scheme" to "No Sounds" and uncheck "Play Windows Start-up sound". This allows for silent operation. 3. Application settings It pays to only install crucial applications on your host computer in the first place. Nonetheless, some apps are required for administration that are not required when the computer is running an installation. Here's how to turn off all inessential programmes, so that they do not automatically start when your account is loaded. This provides more resources for your applications and avoids distractions that might occur. Click "Apps" in the left panel. Then choose the final option in the right panel, "Startup". Now you can pick and choose. Additionally, it is a good policy to manually launch every application that normally reminds you about updates and find out how to turn off those reminders. This setting will be hidden in their configuration settings. Ditto for application in your status bar. 4. Windows updatesIt's important to turn off automatic updates to Windows, so the computer will not be plagued with reminders and pop-up prompts. For this we use the Services interface. Tap the Win key or otherwise view the Start menu. Type "services" and when this displays in the right-hand panel, click "Run as administrator". Scroll down to "Windows Update" and double-click this entry. Change the "Startup type" pulldown menu to "Disabled". Click "OK" and close the dialogue. B. Adding a remote User The above tasks will have been accomplished using your main User account, which has Administrator permissions for full local access. But it's important to have a more restricted account ready for remote access. In the same Settings panel we used above, choose the "Accounts" tab in the left panel. In the right panel, scroll down to "Other users". You will see that Microsoft has thoughtfully provided a Kiosk mode. This allows you to set up an account that will run one and only one application when it launches, denying access to all other functionality. This might work for you, but other times it is too limiting. An installation might have multiple applications or require occasional access to system settings. The alternative is to manage an account manually, thankfully not too complex a task. Click "Add account". Now we enter the world of corporate assumptions, namely that we have a Microsoft account that we wish to use globally. Avoid this requirement by answering "I don't have this person's sign-in information" and then "Add a user without a Microsoft account".Now we can fill in the name of this User account along with the password and a number of silly reminder prompts. These are irrelevant to remote access. We then return to the Settings window where we have additional options for this account. By default the new account has been set up with the account type "Standard User", which limits access to systems changes. The only other option is an "Administrator" account, which has full access. If you are familiar with other operating systems, this will seem overly simplistic. But know that Windows has, in fact, a granular system of access permissions, hidden away in esoteric applications. Thankfully these are not required today! C. Automating log-in The next task is to automate the login process, so that when the host computer is turned on, it will automatically choose "remote" from the available users and log us in with the password. Naturally this process compromises security. But it makes sense for a host that is on-site, under lock and key.Download the Autologon utility here, install, and run. You will be greeted by the simplest of dialogues. Your username should be "remote" or whatever else you chose in task B. Domain is the name of the host computer set in task A. Then, supply the password.D. Wi-Fi accessAssuming that you will require remote access, the final task is to ensure the host computer can connect to the local Wi-Fi. Get the required password and ensure that this network is the default and set to automatic login.ConclusionCongratulations, you are done! Once complete you have a computer set up for automated use on site. it will need only occasional maintenance henceforth. For example, before each installation I log into the main administrator account and apply and security and Windows updates. You may now wish to read my article on Remote Computer Access.
I regularly create gallery installations where audiovisual material is run on a computer that a) might difficult to physically access, and b) must be run with the minimum of technical knowledge. In these cases it is much easier to administer the functionality using a second remote computer. First, read Configuring a Computer for Gallery Use, which explains how to set up the host computer. Then return here. JustificationWhy is this information useful? There are two reasons why you might wish to access a computer remotely. First, because the “host” computer, the machine running the installation, might be hidden away in a plinth or behind an access panel. My most recent pieces have been driven by a small form factor computer (SFF), only slightly larger than 12 by 11 by 4 cm. This is compact enough to fit on the VESA mount of a monitor, or be hidden almost anywhere. In many cases I prefer to run this computer “headless”, that is, without a keyboard or mouse. because these are far bulkier than the computer itself. The cabling and need for a work surface complicates the physical installation. Indeed, for an installation producing only sound, even the video monitor might be surplus to requirements. The “client” computer is the one you use to access the host, likely a laptop. Subsequently, during the course of the exhibition, invigilators can use their own computers to maintain the installation. Again, without requiring physical access to the host. This makes the whole process so much easier. And anything you can do to help gallery staff, you really should be doing! I take ease-of-use into account when coding my applications. If volume controls and a mute function are provided within the app itself, users won't require to make system changes. In this day and age not everyone knows the basics of computer use. Keep it as simple as possible! Microsoft and corporate solutionsMost internet resources (such as this one) explain how to configure Windows Desktop Services (WDS), a corporate solution for virtualisation and remote access. Additionally, there are third party solutions used in the corporate world (for example AnyDesk and TeamViewer). But these enterprise products tend to be sophisticated, complicated, and expensive. Microsoft also documents Windows Remote Desktop (WRD), a "lightweight" solution that allows you to access a computer running Windows 11 Pro from a different Windows or Mac computer (also supporting mobile devices). But this has additional complexities undocumented on the simplistic how-to page. For example you will need to change user group permissions using esoteric tools that can have detrimental effects is mistakes are made. After much bother I was successful in getting Remote Desktop to function, only to encounter a show-stopper problem. This software allows you to choose between local or remote sound devices and also peripherals such as printers. But configuration for attached video devices (screens and projectors) is sadly lacking. This means that while running Remote Desktop all visual output goes to the client computer only. This is obviously unsuitable for any installation where you need to tune video output from the host in that physical environment. Chrome Remote Desktop Thankfully Google has provided software that fits our needs perfectly. Chrome Remote Desktop (CRD) works directly in the Chrome browser as an extension. This also supports Mac and Linux systems, which is fantastic. First, set up the host. Choose "Remote Access" in the left panel, then "Set up remote access". Download and install the software when prompted. Then provide the name of the computer, which should be the same as the Windows computer name for consistency. Finally a numerical password is requested. You can then exit the software. There is a second option worth mentioning. "Remote Support", generates an ID string that is valid for a limited period of time. This is useful if you need technical help on your computer and wish to give someone else temporary access, so they can guide you through a process. But with the option we have chosen the host does not even need to be logged in. The computer merely needs to be powered on and it can be remotely controlled. Now, on the client computer you should also download and install Chrome Remote Desktop. Under Remote Access you should see your host computer listed. Click this and enter the password. This computer will henceforth be available here immediately. Final wordPerhaps it goes without saying, but both computers need to be on the same local network to communicate. Neither WRD nor CRD support Bluetooth. You will need to ensure a good WiFi connection, which can be difficult in a large space or a building with solid walls. A cabled connection (Ethernet) also works, but sacrifices convenience. However, if you can walk up to the host with a laptop, connecting with a cable might be an easy solution. The problem here is that Ethernet ports are increasingly not found on portable computers!It is also possible to communicate over an internet connection between any two connected computers. This requires port forwarding or a VPN, advanced topics that I leave you to discover. Software such as AnyViewer claims to make this process trivial, but I have yet to experiment with such commercial applications.
On democracy (from 2019)
As I wrote in 2019... I am very sorry for my friends in Brazil. It is hard not to despair. The source of the problem is easy to understand but hard to fix. A democracy only works in a small state. Because people inevitably vote for their own interests and those of the people around them, the community they can see. Unless they are particularly knowledgeable, they will be unaware of how their vote might impact someone living in very different circumstances. The larger the territory over which their vote matters, the more likely it is to conflict with the interests of someone else. So a vote in Salvador effects Manaus, and a vote in Porte Alegre effects Belem. Democracy cannot work in a large, disparate country. The centralised and amalgamated power base naturally changes to become a dictatorship (either in name or functionally). And it is also easier to control by vested interests like transnationals and the military. Then a very few people control the fate of the very many. Federations like the USA, Germany, Brasil, Russia, etc. can only work as loose federations. As one "united state" with centralised government, they become autocratic. We can see the same in the EU as a whole. As a loose federation, it can be fine, making trade agreements and establishing common standards for human rights, etc. But as soon as power is centralised too much, it inevitably becomes undemocratic, no matter what the electoral system. The only answer is to break up all large states. This is called anarchy and has a bad name. Because the vested powers (including those of hyper-capitalism) know it is their end. If Brazil was a loose federation of 20 states, each with their own governments, it would be harder for fascism to take root. People are less likely to vote for hate when their own neighbours are the target. It's also much harder for a politician to lie about circumstances when they are visible outside your own door. And even if a smaller state did tip to authoritarianism, countervailing tendencies would soon limit its damage. That state would be isolated (economically and politically) and the voters would feel these hardships. And in response to prompting... OK, now I understand more where you are coming from. Thanks for explaining. Let me address your points. 1. The easiest way to govern is a dictatorship. So anything that moves us towards the other pole is good, IMO. Government and decision-making should never be easy. Consensus takes more energy to achieve and is all the better for it. 2. Some people will always be especially committed to political process, for whatever the reason. And others will not, and hence might be seen as being disenfranchised. But this effect is far less in a consensual system that what we have now. Truly the entire populations of many so-called democracies (UK, USA, Canada, Russia) are currently disenfranchised. 3. Your implication that [consensual government] can never work is wrong. You are extrapolating from your own experience. I need only point to the native nations of North America who successfully existed for thousands of years. Along the way there were conflicts and minor ecological damage. But this was tiny compared with what democracy has done... millions of dead, 60% of all species wiped out (today's headline), etc. There is simply no comparison. 4. Volunteer organisations need not have a "recurring self-destruct pattern". My experience is that this does not come from within, if they are properly constituted. That is, with the proper checks and balances that all political systems need. However, many such groups are set up with too much idealism and not enough structure. Where I have seen such groups fail is when fascistic individuals are able to assume control based on this lack of controls. I've been there and, yes, it hurts like hell when that happens. 5. Large states are always dysfunctional. The centralization of power creates a concomitant lack of empathy to local situations. Citizens are estranged from the politicians and from each other. Non-egalitarian interests can take hold, because there are only a limited number of decision points where they need apply force. None of this can happen (or nowhere near as easily) in a system of distributed and shifting power. Of course there is no perfect system. But it makes no sense to continue in an obviously broken regime that is demonstrably vulnerable to fascism in most every aspect.
Jobs I have done
Here are all the jobs I have had, but only including those for which I received compensation or official designation. Sometimes I even managed a working wage. This is why I've had a hard time being middle class. Though my "standing" has supported that label, the amount of labour I've performed merely to survive has me thinking that I am "working". During public education:DishwasherNewspaper delivery boyGrocery store clerkChinese take-away clerkBus-boyDuring higher education:Psychology test subject (briefly)Applied Mathematics research assistant (one summer)Physics lab assistant (another summer)Accounting clerk (a final summer)Mathematics tutorDriver (for a car dealership)Concert photographerNewspaper reporter (entertainment)After graduation:SecretaryReceiving and shipping clerkRadio producer and DJPrint designerFront of house (theatre)Corporate trainerTheatre sound designerLive mix engineerNewsletter coordinatorParty Riding Officer (for the Green Party)Record store clerk (at Sam the Record Man)Database programmerChief Technology OfficerArt gallery invigilatorProofreaderConcert curatorMax/MSP trainerMedia coderBook editor and designerJournal editorCurrently:Record label ownerUniversity lecturerDirector Editorial Board memberMusician and performerMusic producerEvent photographerFestival organiserOriginally posted to Facebook September 2020, updated February 2025.
L'esprit de l'escalier
Being a collection of nonsense culled from everyday experience.Fields have eyes but woods have ears.As metaphors go, it doesn't hold a candle to the light fantastic at the end of the tunnel.I may not be able to describe the processes in the heart of the sun, but I can still be warmed in its light.Everything is a cynosure if you look the other way.Save the rain florists!Error statement: Expected unqualified id before if.I save my egg collection in a special albumen.Cause of death? Life.Retort: I bet I could fix you with one line of code.T-Shirt Idea: Excellent Shirt of the Wolf: +2 Movement, +2 CharismaI was looking for a good alias and found Nyquist.GOAL: To make music under the sign that erases it.I've got a rootkit in my brain!The sun plays havoc with our glorified calculators.Our house still rocks as earwitness to the thunder.Today I venture under this sign: The Three Of Crows.And fireland was ablaze.Game idea: Several individuals, whose origins are mysterious and purpose unknown, engage in unauthorised activities inside the demilitarised zone. No wait, that's been done. And it wasn't a game.
Comparing compact 85mm lenses
After obtaining a new lens I enjoy making a few quick comparisons with what I already own, so that I can determine the strengths and weaknesses of each optic. These test are not meant to be scientific, so please take with a grain of salt. Sample variation may have a large bearing on the results. In this article I will compare three compact 85mm (or thereabouts) lenses available (from Olympus, Carl Zeiss, and Pentax) with the native Panasonic Lumix counterpart. I find this focal length particularly useful for gig photography, since in the small places I frequent, anything longer would put people between myself and the subject on stage. Anything shorter won't have the reach needed to isolate a performer. The four lenses Olympus OM-SYSTEM Zuiko AUTO-T 85mm 1:2 (1979) 47mm long 260g 85cm close focus 49mm filter 8 blade iris 5 element in 4 group This is the fourth and last variant of this lens (serial number above 204,000) with the newer “NMC” lens coating. I have recently discussed this lens in a series of three articles. Carl Zeiss Sonnar T* 2.8/85 (1975) 47mm long 230g 100cm close focus 55mm filter 6 blade iris 5 element in 4 group I have written a full review of this great lens. smc Pentax-FA 1:1.8 77mm Limited (1999) 48mm long 270g 70cm close focus 49mm filter 9 blade iris 7 elements in 6 groups This an auto-focus lens that uses a screw mechanism. The fit and finish is excellent, complete with a pull-out hood and felt-lined cap. The optics are based on the previously released Pentax-A* 1:1.4 85mm. But Jun Hirakawa tweaked the optical formula for a unique balance of aberration correction (less) with dimensional rendering (more). Well, almost unique, as he did the same with the FA 43mm Limited. I absolutely loved this lens when shooting a Pentax system. The only limitation is the purple fringing against high-contrast backgrounds. Panasonic Lumix S 1:1.8 / 85mm 82mm long 355g 80cm close focus 67mm filter 9 blade iris 9 elements in 8 groups This excellent lens is made with two ED (Extra-low Dispersion) elements that have eliminated chromatic aberration. It has negligible breathing, low vignette, great flare control, almost zero distortion (0.07%) and amazing sharpness. Really there's no technical reason to prefer a vintage lens to what current technology can provide. But what I like about is their handling and compact size. Hence this comparison. The crystal test All tests were performed using my Lumix S5 body on a tripod with IBIS turned off and a delayed shutter to ensure stability. Developing was in Affinity Photo with almost all my usual settings turned off. A slight bit of clarity was maintained since this only reveals what is actually in the image, as opposed to artificially sharpening. A properly developed image will look nicer than these samples.I took a 1000 pixel square from the centre of each image and mosaiced these for comparison at several apertures. The first subject was fruit in a crystal display setting. I was hoping the backlighting would enhance any chromatic aberrations or flaring. It's winter in Ireland... there is no good light! Distance was about 1.4m. You should click on these images to view a full-sized versions. Make your own observations. The Olympus is already capable from wide open. Indeed, this example shows no improvement stopped down to F2.8, but a dramatic increase in detail and precision occurs at F4. This strange behaviour could be an artifact of this particular test. Or perhaps my focusing was off. By F8 the image looks fantastic, as we'd hope for any decent lens. The Sonnar is completely usable from wide. Not sure what else I can say about this wonderful lens that I haven't already covered in my review. I didn't shoot the Pentax Limited wide open but rather stopped down slightly to F2. Even at F2.8 it doesn't quite have the clarity of the Sonnar. There's no sign of purple fringing in the glass, which was a welcome surprise. The screw motor means that the manual focus feeling is not as nice as the Olympus and Zeiss. It's not even as smooth as the Lumix, since Panasonic implement a customisable focus-by-wire system that is quite amazing (for an auto-focus lens). The Lumix leaves nothing behind in terms of pure image quality, as you'd expect for a contemporary design. The entire Lumix line is superb. Even the 20-60mm kit lens, which made me rethink my expectations of a cheap zoom. It's clear from the images that these lenses have a range of magnifications, despite their focal length designations. The Pentax displays the widest field of view, as we might expect from a unit labelled 77mm. But that number was chosen for its associations with good luck in Japan and is no doubt an approximation. The Lumix has a very similar FOV, followed by the Olympus and then the Zeiss. Consulting the Zeiss technical notes, we see that the focal length is specified at 87.6 mm. Rounding off a bit, here's my guess as to how these lenses relate: Pentax: 78mm Lumix: 80mm Olympus: 85mm Zeiss: 88mm These small differences may or may not matter, depending on the rest of your kit. Though by no means a stress test of bokeh, since the background is so far from the focal plane. All of these images have a nice smooth background with no disturbing qualities. I'd say that the Olympus renders more smoothly than the Zeiss, likely due to the increased colour saturation and contrast that the Sonnar is known for. One characteristic plays off the other. The colour test My second subject is a knitted throw made of coloured wool, chosen for the diverse hues. I omitted the Lumix lens and F8 for this test. The subject was at a slight angle to the camera, so that even if I missed focus, part of the material would indeed be sharp. Here the Olympus operates as expected, the previous test notwithstanding. Wide open the image lacks clarity but is very tight and detailed already at F2.8. It doesn't gain in quality as you stop down from here, which in practice means that you can choose your aperture strictly based on the desired depth of field. The Zeiss is sharper than the Olympus at F2.8 and has deep, saturated hues that are difficult to find elsewhere. I know this from practice. Sometimes I need to back off on the contrast and saturation during development because the Sonnar is altogether too vivid! The Pentax Limited comes into its own at F4, which is something I know from experience. For portraiture, at the usual expected distances from the subject, F4 is also perfect for rendering enough of a face in focus. Indeed, when close to my subject this might not be sufficient. As evidence I present Schweppes at F4 (taken with the Olympus 85mm). Focus is on the nose, but the eyes are not yet quite sharp. Conclusions Despite taking these attributes into account in this comparison, it must be said that neither colour nor contrast are that important. Back in the film era one might choose stock specifically for its colour rendering and how this interacts with a specific lens. Now, both characteristics can be tweaked instantly in digital development. I bought the Olympus 85mm since I had never shot with any OM Systems optics and kept reading about how highly-regarded they are. The prices are rather astronomical for some of the lenses, though the 85mm is not out of line for a vintage lens. And it is the most compact 85mm that does F2. However, following my tests (and other shooting) I won't be using the Olympus at F2. That restriction puts it up against the Zeiss Sonnar, which cannot be beat on image quality and is fractionally smaller. It's also much nicer to use. The Olympus aperture ring is too loose and I don't like the placement at the front of the lens. It's too easily knocked in normal use. Ergonomics is important. In fact, it's why I am using vintage lenses in the first place. The smooth focus rings and visible apertures are two reasons I prefer these over contemporary products. The Pentax unfortunately can't compare since its focus ring is optimised for auto-focus. However it has the advantage of close focus distance, only 70cm. The Sonnar is the worst in this respect at 1 m. And that is its only limitation. Finally, I should remark on the slightly veiled look of the Olympus. This might be the result of a slight hazing of the elements. Then again, this might be considered a desirable aesthetic, especially for portraits. There is such a thing as "too sharp" when rendering skin. Reality check: Any and all lenses will take great pictures once you know the strengths and weaknesses. But the small details matter when you wish to get the most from your tools. I hope this article has helped in that regard.
The banana as post-symbolic currency
This is a brief response to the hullaballoo concerning a duct-taped banana. Naive knee-jerk responses have been anticipated by both artist and buyer, both aware of their roles in this game of post-symbolic trade. It's a basic error to view an art transaction as having any basis in the object itself. This has obviously been false for some time, else even a representational painting (la Gioconda, say) would not be worth one billion dollars. That is a mad figure since no matter how good the artist, the painting is not 100 million times as "good" as another. One might criticise/defend the waste/investment of money on the basis of the work's functionality, reproducibility, and so on. But it's understood (I would hope) that the purported value incorporates a web of cultural associations, historical resonances, and aesthetic interpretations that fan out from the object in endless tendrils of association. Not to mention how much you can make, over time, from Louvre ticket sales. Maurizio Cattelan's Comedian (2019) was already a joke, as its content, presentation, and title make plain. To make fun of the piece after the fact is a pathetic response. Such reactions come too late to have any effect on an art world already deeply self-knowing, self-critical, and self-involved. One may as well critique the bone flute of proto-human ritual as "something even my child could make". It might help (or further annoy) to know that Comedian comes in editions, three of which have already sold for prices between 120 and 150 kilobucks. Though the most recent purchase at $6.2 million did indeed trump (ahem) those valuations. Now, that's a lot of money to you or I, but is it really a meaningful amount to Justin Sun, a cryptocurrency "investor"? Crypto is a pyramid scheme even more obviously unethical than the stock market. In fact, I once believed that crypto was invented specifically to highlight just how broken monetary investment is, so as to undo the entire structure. It hasn't worked out that way, because people are willing to believe in illusory value right up until the moment their investment disappears into worthless stock in the South Sea Company. Or tulips. Somehow, it's fitting to transform dark earnings from crypto into the similarly tainted currency of conceptual art. Sun has exchanged the symbolic assurances of megabucks for the symbolic irreverence of a taped banana. This transaction was performed as a self-evident joke. In truth, nothing was even sold; no, not even a banana. The auction was for a certificate of authenticity. This gives Sun permission to duct-tape his own banana to a wall and call it Comedian. "Additionally, in the coming days, I will personally eat the banana as part of this unique artistic experience, honoring its place in both art history and popular culture," Sun said. Any of us could do the same, even without a certificate, and the act would be identical. Or... would it? For me this gets a pass. I don't like bananas.Credit: The image is a still from a 3D rendering by bvchepovyi, CC BY 4.0.
Optical design of the Olympus Zuiko 85mm
In my previous articles I introduced the Olympus Zuiko 85mm and discussed the thorny problem of variants. This post will conduct a thorough examination of the optical formulas that Olympus deployed and their relationship to the classic Ernostar and Sonnar designs. Searching for patents I thought the most logical next step was to search for patent applications and see which matched the lens diagrams as supplied by Olympus literature. The best possible renderings of the optics were obtained from two sources. Olypedia has a scan of the 6/4 diagram from a German instruction booklet dated 1973. User eggplant_ on Flickr provides a high resolution scan of the 5/4 design from an undated Olympus lens catalog. For consistency with the remainder of this series, I redrew these designs in my house style. This enables us to clearly examine similarities and differences with important historical precedents. The patent search proved as surprising as anything else in this article. Restricting myself to an appropriate date range and the assignee "Olympus Optical" I eventually found: US patent 3848972 “Large-Aperture Telephoto Lens” by Sumio Nakamura, 11 April 1973US patent 4063802 “Telephotographic lens system having short total length” by Toshihiro Imai and Yoshitsugi Ikeda, 14 July 1976 I have strong confidence that these correctly match the lens in question since the diagrams conform exactly to what Olympus published. The first patent makes clear that the fourth element can float to correct for aberrations (astigmatism and coma) at short distances. This is an innovation for a telephoto lens that would otherwise optimise quality only at infinity. The second patent further specifies the lens as f/2 and “80mm or so”. (The floating element is now the third.) What is surprising is that the first patent is dated 1973, a year after the lens in question was released to market. To confirm, I continued my search back through time to the very first Olympus photographic lens patents but found no others that matched the 85mm. The only logical conclusion is that the firm applied for intellectual property protection in a tardy manner. The second patent was dated 1976 and the lens design in question was released in 1979, which is a reasonable timeline. I note that the "short total length" of the lens is here claimed explicitly, unlike the first patent. Indeed this lens vies with the Carl Zeiss Sonnar T* 85mm F2.8 for Contax-Yashica mount (as previously documented). Relationship to Sonnar Jason Schneider included this lens in his "10 Exceptional Zuiko Lenses in Olympus OM Mount" (Rangefinder Forum, 27 November 2020). He notes that V1 is "a bit soft wide open, and more prone to flare, but some claim it’s better for portraiture". The redesign is "sharper across the field at f/2, delivers images with higher contrast overall, and has better correction for chromatic aberrations". In another useful article from 2020 David Braddon-Mitchell provides capsule reviews of the entire OM line. He repeats the common opinion that the original design has a “true sonnar” look. The relationship of the OM 85mm to the famed Sonnar design pattern is worth elucidating. There are several places where we can read histories of the Sonnar lens, but I will use Kingslake's 1989 volume A History of the Photographic Lens. The innovations of Ludwig Bertele (1900-85) are usually simplified into two design threads. First comes the Ernostar f/2 of 1923, designed for the Ermanox camera. This had two cemented doublets in a 6/4 design with elements on either side of the aperture stop. But his second Ernostar design had a cemented triplet and the third had only one doublet, no triplet. So that's three quite different geometries in two years, not even taking into account differences in the element shapes, refractive indices, etc. In 1931 Bertele patented his first Sonnar. This had six elements in three groups with a distinctive cemented triplet before the stop and a doublet after. Yet the following year an F1.5 Sonnar had a 7/3 formula with two cemented triplets. Much later the Zeiss Jena Sonnar 180/2.8 was 5/3 but again with a triplet. In both cases, Ernostar and Sonnar, it's unclear what the key features are that define these templates. It's now worth looking at the aforementioned Carl Zeiss Sonnar T* 85mm f/2.8 from 1975. This is described as 5 elements in 4 groups in the official literature, although the diagram incorrectly shows an air gap between the last two elements. (This contradiction has been corrected in my diagram.) (I tried to find the designer or patent for this lens with no luck. Can anyone help?) We observe that the five elements that remain from the original Sonnar design are similar in geometry, and we retain the cemented doublet. This is fundamentally similar to Bertele's later Sonnars despite not having the triplet of the original. Let's compare the OM 85mm starting with the Nakamura 1973 design. It does not have a cemented triplet, so isn't like the original Sonnar. But it does bear a distinct resemblance to Bertele's 1923 work. There's a cemented doublet and the distinctive fourth element. The second doublet has moved past the stop and the initial surface is planar. Though we can recognise genes from the Ernostar family, it's quite a unique design. It may render like a Sonnar but it's not a Sonnar. The Imai and Ikeda 1976 design effectively combines elements 2 and 3, while retaining the overall lens shapes of the original optic to a significant degree. It is definitely a Sonnar of the 1970s. In fact, it is quite similar to the Carl Zeiss lens we just examined, which had precedence. It's unlikely that there was sufficient time for Olympus to actually copy Zeiss, so this is likely a case of convergent evolution. As time went on, Sonnar lenses lost popularity to derivations of the double Gauss formula, as outlined in a previous article. When Zeiss revived the use of "Sonnar" to describe their telephoto lenses they were using the term for its marketing spin and not for any accuracy in describing the optics. But, as I hope this analysis makes clear, there is very little to qualify a given design as a Sonnar or Ernostar. To list the characteristics:total element count of five or sixfirst element is a thin convex-planarsecond group is a single element or a cemented doublet in a thick convex-planar shapethird group (element three or four) is plano-concavethen the aperture stopfinal group is a cemented doublet, usually planar-convex with concave-planar
Olympus Zuiko 85mm variants
In my last article I introduced the Olympus Zuiko 85mm and compared its properties to my other two 85mm lenses. In my next article I will describe the optical formulas employed by Olympus.In this post I'll explore a mystery that haunts this lens. Various writers claim that there are from two to four different variants. They don't agree on the particulars beyond the important fact that there were two different optical designs. Early lenses used 6 elements in 4 groups while later lenses used 5 elements in 4 groups. Photographers enjoy the original for its classic soft portraiture and claim the latter has superior sharpness and aberration correction. My goal is to sort out the confusion. Further information or corrections are welcome! Possible variants of the OM 85mm What are the possible variations? I will describe these using the exact markings found on the front inner ring. V1Olympus OM-SYSTEM F.Zuiko AUTO-T 1:2 f=85mm This first design, released in 1972, is well documented and is not in question. This is referred to as the "silver nose" after the chrome rim. I guess that makes all other variants "black nose"... but no-one calls them that. The glass is single-coated. Note that the first letter of the Zuiko designation tells you how many elements were used in the design. Thus F.Zuiko means six elements, F being the sixth letter of the alphabet. Subsequent iterations of the OM line removed this designation. V0Olympus OM-SYSTEM F.Zuiko AUTO-T 1:2 f=85mmOlympus OM-SYSTEM F.Zuiko MC AUTO-T 1:2 f=85mm The same lens as V1 with a black nose. I am numbering these variants with a zero since (spoiler!) there appears to be no physical evidence that they exist. The "MC" designation indicates multi-coating. V2Olympus OM-SYSTEM Zuiko AUTO-T 1:2 f=85mm The same name as V1 but with the "Z." missing. Perhaps released in 1979. Likely multicoated though it has no "MC" label. V3Olympus OM-SYSTEM Zuiko MC AUTO-T 1:2 f=85mm Perhaps also released in 1979 or maybe the MC designation was added at some later date. Might be identical to V2 except for this label. V4Olympus OM-SYSTEM Zuiko AUTO-T 85mm 1:2 Here the MC designation is dropped but the multi-coating has been improved to a newer “NMC” coating, whatever that stands for! Note the labelling "85mm 1:2" that is different from all prior versions. This is the one I own. Different sources claim that different variants exist. These will now be outlined. Olypedia is a crowd-sourced encyclopedia developed by the members of the German Olympus forum and Reinhard Wagner. This source claims that there are no extant copies of V0, even though other lenses in the OM line do have such a variant. I take this claim as definitive. They provide photos of serials 106xxx and 113xxx for V1. Olypedia also claim V3, illustrated with serial numbers 200xxx and 209xxx. But this last example has the wrong inscription and so belongs elsewhere. V4 is claimed as the first 5/4 variant, illustrated with serials 208xx, 212xxx, and 216xxx, alongside a 201xxx that is obviously in the wrong category (wrong inscription again). If we put the images into the correct categories, we have V3 spanning serials 200xxx to 201xxx while V4 spans 208xx to 216xxx. The Olympus OM Blog (author: Matthew) credits Konrad Beck for serial number information while claiming the following variants, without being explicit concerning markings. V1 with serials 100xxx to 115xxx. V3 with serials 200xxx to 204xxx. V4 with serials 204xxx to 210xxx and above. These do not contradict the previous serial information. This source also claims a V0 with MC marking and serials 116xxx to 130xxx in 5/4 design. I will assume an error here, and that this is instead the V2, since no other variant could exist in this serial number gap. LENS DB (author: Evgenii Artemov) is a reputed site that compiles information from manufacturer publications. This source lists V1 and V0 together as the original 1972 release in 6/4 design and V3 and V4 together as the 1979 release in 5/4 design. An image of V3 has serial 203xxx. Actual variants of the OM 85mm?So, there are contradictions and confusions. Nonetheless, the most logical summation follows. V1. Olympus OM-SYSTEM F.Zuiko AUTO-T 1:2 f=85mm1972, "silver nose", 6/4 design, single-coated, 100xxx to 115xxx V2. Olympus OM-SYSTEM Zuiko AUTO-T 1:2 f=85mm1979, multi-coated despite lack of MC, 6/4 or possibly 5/4 design, 116xxx to 130xxx V3. Olympus OM-SYSTEM Zuiko MC AUTO-T 1:2 f=85mmafter 1979, multi-coated with MC, 5/4 design, 200xxx to 201xxx V4. Olympus OM-SYSTEM Zuiko AUTO-T 85mm 1:2after 1979, NMC coating, 5/4 design, 208xx to 216xxx If the large gap in serial numbers indicates a redesign, then V2 is more likely the 6/4 design. Maybe. We could get confirmation if anyone has disassembled that specific variant, or from a lens service manual. Some photographs Yes, I will eventually post photos I've taken with this lens. But in the meantime... The famed portrait photographer Jane Bown (1925–2014) was known for her black-and-white work for The Observer. She almost exclusively shot the Olympus 85mm at 1/60 and f/2.8 using natural light. View that claim and her portfolio.
Olympus OM 85mm lens: introduction
Olympus launched their range of single-lens reflex (SLR) cameras with the M-1 in July 1972. The next year this camera was renamed the OM-1, the initials apparently standing for Olympus Maitani, honouring chief designer Yoshihisa Maitani (1933-2009). So began the famed OM System. This article provides information on the Olympus Zuiko 85mm. The second article will examine the mystery of the different variants. I've now finished a third article that dives into the optical design.The OM-1 was distinctive in having the shutter dial around the lens mount, a space-saving feature. To improve ergonomics, OM lenses had their aperture dial moved to the front of the lens. This provided convenient one hand control of both essential exposure parameters. While this distinctive feature did not appeal to all photographers, the compact size of the camera system was compelling. Miniaturisation was taken even further with the half-frame Pen cameras (1959), a name re-used in the digital era for Olympus's micro-four-thirds mirrorless cameras. Though I bought several of those digital models (and also have an original film Pen) I have not owned any OM lenses... until now. Also released in 1972 is the Olympus F-Zuiko AUTO-T 85mm f/2, though here I have a later variant. Though I already own two 85mm lenses, I was curious about how the tiny Olympus model compares. Here are the stats, confirmed by Olympus promotional brochures, technical data sheets, and my own measurements. Note: The length specified here is what's visible when mounted on a camera. There are additional projections on the mount, extending back into the body, as is typical for bayonet mounts. 48mm long, extending to 61mm 280g 85cm close focus 49mm filter ring 8 blade aperture, stopping down to f/16 29 degree angle of view This is sometimes described as the smallest 85mm ever designed for SLR cameras. That's not quite true. The Carl Zeiss T* Sonnar 85mm f/2.8 is the same 48mm in length but extends slightly less, to 56mm. It is also a tad lighter, at 245g. However, it is a stop slower. The achievement of the Olympus engineers with this lens is singular. Here's a comparison of the OM 85mm with the Zeiss Sonnar 85mm and the Panasonic S 85mm F1.8, a contemporary lens. The Panasonic S 85mm is 82mm long but, like most contemporary lenses, is also significantly larger in circumference. But thanks to plastic and new composites the weight is a very reasonable 355g. These Panasonic lenses are indeed excellent, which is why I own three models despite having a preference for the ergonomics and usability of vintage glass. The OM lenses use what was then called an "automatic" stop-down mechanism. Even when you rotate the aperture ring the iris doesn't change, but stays wide open. You must press the two switches on the exterior of the barrel to stop down. I've highlighted these blue in the next photo.An OM camera would have done this automatically. Two levers (highlighted yellow) travel a small arc around the lens mount. The camera uses one of these to set aperture and the other to top down. (Most if not all SLR manufacturers devised a similar mechanism.) So be careful when using such a lens on a digital camera. The lens mount adapter must hold the stop-down lever in place, or else the aperture dial will do nothing! I make it a habit of buying K&F adapters since they are inexpensive, have a good fit and tolerance, and always seem to "just work". You can pay many times more for what is essentially a metal tube with the correct screw pitch or flanges in place. Snap the lens onto the adapter by starting with the K&F logo placed to the left of the position below. Then rotate so the logo lines up with the infinity marking when in place. It is possible to screw on the adapter at other angles, but then the stop-down lever will not be held open. Once on the lens it's rather difficult to take off, given that there are few places where purchase can be obtained. I am in the habit of always using a lens hood. This guards against flares that are more likely on older lenses. But more importantly, a short metal hood will protect the front element from damage. Once you add the adapter and hood, a vintage lens loses much of its size and weight advantage compared to a contemporary lens. But it retains the ergonomics and rendering.My copy of this lens has a very loose aperture ring. I image this is the result of a cleaning / repair job at some point in the history of the lens. After all, it is 40+ years old!Writers claim that there are anywhere from two to four variants of this lens. They don't agree on the particulars beyond the important fact that there were two different optical designs. Early lenses used 6 elements in 4 groups while later lenses (such as this example) used 5 elements in 4 groups. Photographers enjoy the original for its classic soft portraiture and claim the latter has superior sharpness and aberration correction. With only one sample I can neither confirm nor deny!In my next article I will explore this mystery and sort out the truth. A deep dive into optical design will also be provided. In the meantime, I am going to see what this lens can do!
Codec limitations of DaVinci Resolve: HEVC, 10-bit, and RAW
Note: This information has been greatly expanded from my previous article on Windows video support. Introduction Like any application DaVinci Resolve has limitations, especially in the free version. Some authors claim that either Microsoft Windows or Resolve (free) don’t support 10-bit video. But this is false. The limitations are more particular than such blanket statements. Read on for solutions. The first two issues affect only the free version of Resolve, so the best solution is to upgrade to Studio, since this provides numerous additional benefits. But there are other methods. HEVC support in Windows Microsoft Windows doesn’t provide native support for the HEVC codec. Applications such as Resolve Studio implement this support internally, but Resolve (free) does not. Neither do most other video applications. The symptom is that clips will appear as “Media off-line” when loaded into Resolve. This is an incorrect error statement. The clips are very much present, demonstrated by the fact that the audio component plays correctly. Thankfully the solution is simple. Go to the Microsoft store and purchase the “HEVC Video Extensions” for €0.99. Install this extension and reboot. It's difficult to understand why this component is already included, but there you go! Rendering to H.264 (AVC) and H.265 (HEVC) Video exported from Resolve (free) might contain artefacts. Tonal and colour gradations that should be smooth will instead display visible banding. This is more likely if extensive colour grading has occurred. If you are using a 10-bit intermediary file in your timeline, then everything will look fine while editing. But when rendering H.264 and H.265 codecs, Resolve (free) restricts you to 8-bit colour. The solution is to export to a different codec that does support 10-bit (e.g. ProRes or DNxHR) and then transcode to the format you require.No ProRes RAW support Due to corporate politics, Resolve does not support ProRes RAW. Nonetheless, this might be a requirement for your project, depending on your client and the camera used. The solution is to transcode ProRes RAW footage to a format such as CinemaDNG and use that in your timeline. This requires a third-party utility; these are all commercial closed-source products. Two notes: First, Resolve does support all other ProRes formats, up to ProRes 444. So you can simply choose to record these instead. Second, Blackmagic cameras also do not support ProRes RAW. So there is no incompatibility when staying within their system. Indeed BRAW is the preferred format in most cases. Transcoding applications There are two excellent free and open source applications that function as interface wrappers around the command-line tool FFmpeg. Both Handbrake and Shutter Encoder run on Windows, macOS, or Linux and are free. However, these do not convert RAW formats, since this requires licensing. For this task there are commercial solutions, such as Assimilate’s Play Pro Studio.
Asahi Takumar and Pentax normal lenses
My interest in Pentax lenses should be obvious considering the articles on this website. One of the reasons I went down the rabbit hole of lens design history was to discover how the numerous lenses released by Asahi Optical related together over time. This article compiles the results of that research.The format is original even if the lens data is available in numerous places. Read on to get a spreadsheet organised chronologically by lens family and optical design. Updated 26 November 2024 to include some lens diagrams. Constraints I've restricted the scope to manual focus lenses released from 1957 to the end of the 1980s. By this time the first auto-focus line (Pentax F) was being marketed. I end here not because auto-focus lenses are bad -- indeed some are superb. But it's a given that the ease of manual focusing in AF lenses takes second place to the ease of motor-driven focus mechanisms. The ergonomics are simply not the same. I've considered only normal primes of either 50mm and 55mm focal length. These conform to the heritage of symmetrical (double Gauss) designs I have recently documented. The 50mm macros and the pancake 40mm use different optical formulas. My major contribution to the profusion of articles already extant is a chronological chart that groups similar lenses, so that it's easier to understand which models should operate and render similarly. Indeed, there is more similarity than difference in these lenses. Especially when used on digital bodies, where the aperture mechanisms are mostly irrelevant. Why Pentax? They simply made some of the best lenses of the time, with a workmanship second to none. Indeed, I have several lenses from this list, now decades old, that still function perfectly despite never having been serviced. Few other manufacturers can make that claim. The ergonomics are also wonderful, with nicely damped rings and controls that fall readily to hand. Aesthetically I prefer Leica and Zeiss lenses with their streamlined sleek looks. But Pentax are far from ugly, unlike other brands I won't mention for fear of offending! It is an amazing fact that only three lens mounts have survived from the vintage days to the present. Two of those are described here: M42 and Pentax K. (The third is Nikon F.)The chartPlease download the full chart as an ODS spreadsheet. This opens natively in LibreOffice or OpenOffice, but you can also use any other spreadsheet application you prefer.Right-click, choose "save link as" or equivalent. If you get some guff about an insecure link, you will need to give permissions. It's not insecure, it's a normal HTTP link! Why is the internet so difficult these days? Oh right: corporations.OK, here's a PDF version as well. Lens lines In 1952 Asahi Optical was the first Japanese company to release an SLR, following the German firms. The Asahiflex (1952-57) used M37 mount lenses with a convenient preset aperture. (Read my article that explains the different aperture mechanisms.) In 1938 Carl Zeiss Jena developed the M42 screw mount. In 1949 the first M42 camera was introduced in East Germany. In 1957 the Asahi Pentax (AP) camera became the first Japanese M42 mount body. This was supported by a range of Takumar lenses. (The brand name was usually stylised in upper case). Asahi's use of this universal mount was so popular that M42 became known to many as the "Pentax thread mount". Asahi Takumar lenses went through five different nomenclatures as features changed. Takumar (1957-59) have manual or preset apertures. The Takumar 55mm F1.8 and 2.2 were standard primes included with the Asahi Pentax (AP). Auto-Takumar (1958-63) added semi-automatic aperture control by way of a stop-down pin. You could stop down using a camera control which was coupled to the lens aperture. Super-Takumar (1962-75) improved the coatings, though still single layer. Automatic aperture control was implemented through a stop-down pin (with M/A switch). In the "A" mode the camera would automatically stop down to the indicated aperture, returning to wide open for focusing and composition. With the release of the Asahi Pentax Spotmatic in 1964 the Super-Takumar 50mm F1.4 became the standard lens. Super-Multi-Coated Takumar (1971-72) again improved the coatings. SMC Takumar (1972-75) standardised the "SMC" naming that would be used in future Pentax brand lenses. The focus ring was now rubber. In 1975 Asahi released the Pentax K camera and a new line of lenses using a proprietary bayonet mount of the same name. SMC Pentax (1975-77) lenses aimed at the highest image quality and included the only Pentax collaboration with Zeiss. As a result these tended to be larger than other lines. Though it has no such designation, these are often called "Pentax-K" to distinguish from the others. SMC Pentax-M (1977-84) lenses were designed at reduced sizes. A few models from the original line were not re-issued (e.g. the 50/1.2), so their retail life continued through the M period. SMC Pentax-A (1984-89) lenses had a fully automatic aperture and communication that permitted new shooting modes on the Pentax Super Program. The lens designs were identical to the M series. Some parts were replaced with plastic for lighter weight. For this reason the "M" line are sometimes considered the pinnacle of this history, though there are naturally outliers in individual lenses. SMC Pentax-F (1987-) lenses were the first with auto-focus screw mechanisms. Some folks are not happy calling auto-focus lenses "vintage" but they are by definition. Though there have been several series since, several models have been kept in production, indicating their quality and popularity. Optical families This section groups extant lenses into families based on the optical design. Lenses in the same group can be considered optically similar, though other factors (metering method, coatings) will differ as already outlined. It is also true that lens materials and indices might have changed slightly between models, in various undocumented ways. In practical terms, the performance you get from a particular lens will depend more on the history of use and abuse of that specimen than other factors. You can't depend on generalisations from other users but must test and use the lenses you have to determine the best fit for a given application. For each family I share specifications in a compact format I devised. The numbers indicate: length / mass / close focus distance / filter thread / number of aperture blades. Numbers have been rounded off. 5 elements in 5 groups This, the simplest lens formula, appears in two families. The first was the original Takumar. The second family were released as inexpensive options for buyers at the time. Takumar 55/2.2 (1957-59)34mm / 155g / 55cm / 46mm / 10Preset aperture. SMC Pentax-M 50/2 (1979-85) SMC Pentax-A 50/2 (1985-98)31mm / 145-160g / 45cm / 49mm / 6Open and automatic apertures respectively. 6 elements in 5 groups There are six families with this improved optical formula. The first two use a 46mm filter thread and have the longer close focus distance characteristic of early Taks. Notice how lenses of different open apertures nonetheless use the same formula. This was a common marketing device: Asahi purposely limited the aperture of some lenses in order to sell them at a lower price, while saving costs on retooling a factory for a different build. Takumar 55/1.8 (1958) Auto-Takumar 55/2.2 (1961-63)33mm / 165g / 55cm / 46mm / 10Takumar is preset aperture; Auto-Takumar is manual aperture. Auto-Takumar 55/1.8 (1958-60) v1 Auto-Takumar 55/2 (1958-59) Auto-Takumar 55/2.2 (1961)33mm / 175g / 55cm / 46mm / 10Semi-auto aperture. Auto-Takumar 55/1.8 (1960-62) v2 Super-Takumar 55/1.8 (1962-65) three variants Super-Takumar 55/2 (1962-73)36mm / 165-215g / 45cm / 49mm / 6Auto aperture. Auto-Takumar is the heaviest. Super-Multi-Coated Takumar 55/1.8 (1971-72) SMC Takumar 55/1.8 (1972-75) SMC Takumar 55/2 (1973-75)38mm / 200-215g / 45cm / 49mm / 6Super-Multi-Coated Tak is auto aperture; others open aperture. SMC Pentax 55/1.8 (1975-77) SMC Pentax 55/2 (1976-77)39mm / 220g / 45cm / 52mm / 6 SMC Pentax-M 50/1.7 (1977-83) SMC Pentax-A 50/1.7 (1983-89)31mm / 185g / 45cm / 49mm / 6The smallest and lightest of this optical family. A lens diagram for this configuration follows. This conforms to the Pentax-M 50/1.7 but is also found in US patent 3,817,603 here. This dates back to 24 May 1971 and is credited to Yasuo Takahashi. 8 elements in 6 groups Only a single model was made with this extravagant formula. This was quickly replaced as the production cost was too high. Super-Takumar 50/1.4 (1964-65)43mm / 245g / 45cm / 49mm / 6 7 elements in 6 groups This optical formula range began with the replacement for the famed 8-element Tak (above). This adds one final element to the 6 in 5 design, for further aberration correction. Super-Takumar 50/1.4 (1965-71)38mm / 230g / 45cm / 49mm / 6 Super-Multi-Coated Takumar 50/1.4 (1971-72) SMC Takumar 50/1.4 (1972-75)41mm / 230-250g / 45cm / 49mm / 8 SMC Pentax 50/1.4 (1975-77)42mm / 265g / 45cm / 52mm / 8The original K range was unusually large for Pentax. Note the filter size. SMC Pentax-M 50/1.4 (1977-83) SMC Pentax-A 50/1.4 (1983-89)37mm / 240g / 45cm / 49mm / 8Notably larger than the f/1.7 variants, but not huge by any means.SMC Pentax-FA 43/1.9 Limited (1997-2021)27mm / 155g / 45cm / 49mm / 8The smallest of all such primes and the only one at 43mm focal length, the exact diameter of the 135 film frame. I include this because it is a distinctive lens that nonetheless follows the classic 7 in 6 formula.Here I compare a famed Carl Zeiss diagram with those discussed above. The similarities are evident, even across designers and several decades of production.7 elements in 6 groups (modified)Some of the lens elements have a different shape from the family above. No double necessary to get to that maximum aperture. The Pentax-A variant changes the aperture blade count, the only such case in the Pentax line. SMC Pentax 50/1.2 (1975-83)49mm / 345g / 45cm / 52mm / 8 SMC Pentax-A 50/1.2 (1983-2004)49mm / 345g / 45cm / 52mm / 9 Which to choose?Generally the newest lens in each category is the best buy for several reasons. First, it will have the benefits of all incremental improvements (to coatings, etc.). Second, the specimen will simply not be as old and so less likely to have issues. Third, it will likely be more compact than earlier designs. Finally, it's likely to be cheaper than rarer and more collectable old models.I am pragmatic, so I own the SMC Pentax-M 50/1.7 for daily photos (starting at f/2.8) and the SMC Pentax 50/1.2 for speed. But I never use the second lens because soft photos and aberrations are not my cup of tea.In decades of practice, I've seen no evidence that a Takumar would improve my photos in any way. However, some people just prefer an older lens for the feeling it gives them. I'm not knocking that!ReferencesI've compiled the information here over several decades from many sources: Pentax Forums (including the Lens Review section), defunct newsgroups, scans of manuals and brochures, etc. For this article I've double-checked the data with Evgenii Artemov's LENS-DB, which can be considered authoritative.Corrections are welcome, especially if you can find further patents and discover designer credits.
Photography and Lens Design SERIES
This series of articles provides historical information on lens design for cameras, specifically those using 135 film, but also their SLR and DSLR offspring. Today's mirrorless camera systems allow us to adapt almost any lens from the history of photography. So there has been renewed interest in how families of lenses are related in their optical design. This series is for readers interested in learning the basics without being overwhelmed by technicalities and mathematics. Here you will find a solid basis for any further readings. The Lens Design Glossary provides definitions of terms, written to flow from one concept to the next. The first section covers basic lens terminology; the second section provides capsule descriptions of common lens aberrations. For further reading, and to acknowledge my sources, I provide Lens Design References. Historically, start with Camera Lenses of the Nineteenth Century. Then read about the subsequent Development of Symmetrical Lenses.This series began by investigating the lens naming scheme of Carl Zeiss. Planar / Tessar / Sonnar / Distagon has now been updated to fit with this series.
Lens Design Glossary
This article provides a glossary of useful terms, written in such a way as to flow from one concept to the next. The first section covers basic lens terminology. The second section provides capsule descriptions of the most common lens aberrations, defects that the lens designer struggles to overcome. In the interest of time I haven't provided illustrations. Please consult other sources after familiarising yourself with this primer. Lens Glossary The image plane is the surface on which incoming light rays form a virtual image of the subject. This is where optical film or a digital sensor is placed. The optical centre is the point at which light rays from different sources cross. This point is usually (but not always) within the extent of the lens itself. The focal length is the distance between the optical centre of the lens and the image plane, when focused at infinity. This is typically measured in millimetres (mm) but traditionally also in inches, for makers in the UK and USA. A shorter focal length bends light rays more sharply and so brings light to focus in a shorter distance. This allows a wider field of view. Traditional focal lengths from the 135 film era include 18mm, 28mm, 35mm, 50mm, 85mm, 100mm, and 135mm. Today 24mm often replaces 28mm in a lens family, while 135mm is uncommon. A prime lens has a fixed focal length and can achieve excellent optical quality (generally speaking). A zoom lens conveniently allows a range of focal lengths by compromising on image quality, size, and/or cost. The field of view is the angular extent of the scene captured by the lens. A wide angle lens has a focal length less than "normal". Historically this included 35mm and below, though by contemporary standards 35mm is not considered wide. Lenses with narrow fields of view (85mm and higher) are typically called telephoto, though technically this is a misuse of the word. A normal lens has a focal length approximating the diagonal of the image plane. For 135 film this is 43mm, but typically lenses from 40 to 60mm are described as normal with 50mm being by far the most common. The plane of focus is the distance at which a subject is rendered with precision. Everything in front of or behind this plane is out of focus, to different degrees. Depth of field (DOF) refers to the distance in which the photograph appears acceptably sharp. This is a perceptual affect that depends on the focal length and distance to subject. For more details read my article on 3D pop. Most lenses are rectilinear, accurately reproducing the geometry of the subject, with straight and parallel lines. Exceptions include the fish-eye lens, which projects a panoramic or hemispherical image, capturing a wider angle than would otherwise be possible. The special effect can be desirable for its own sake. The iris is a mechanism that allows control over how much light can enter the lens. Several mechanisms have been designed for this purpose, including a circular wheel with a gap in the arc (common in cinematography) or a simple blind that moves horizontally or vertically (common in early cameras). Contemporary photographic lenses use an overlapping system of curved blades that provide for a more-or-less circular opening at all sizes. The number of blades is sometimes taken as a measure of quality but other factors are equally (or more) important. The aperture is the lens opening itself, the word being Italian for window. The terms iris and aperture are used interchangeably and often incorrectly. Aperture is more common in photography while iris is more prevalent in cinematography. An f-stop (also f-number) is a measure of aperture size and hence how much light is gathered. This dimensionless value is calculated by dividing the focal length by the diameter of the entrance pupil. As the number gets larger, the aperture gets smaller, since it is on the denominator of the expression. Each doubling of the denominator halves light. These increments are called a stop. Typical f-stops for 135 cameras include f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, and f/22. Lens speed is indicated by the highest f-stop (the lowest number). A lens that can open to f/2 or greater is generally considered to be “fast.” These terms relate back to optical film development. Magnification is a dimensionless quantity that expresses how large the subject appears on the image plane. A magnification of 1:1 reproduces the image size without a change in size. Generally a shorter focal length provides a wider field of view but offers less magnification. Conversely, longer focal lengths provide less field of view but greater magnification.Lenses specifically designed for close-up photography are termed macro, which, strictly speaking, is reserved for those that attain 1:1 magnification. However, a lens labelled “macro” might in fact only magnify 1:2 or less. The close focus distance specifies the closest a lens can focus on a subject. This is measured from the film (or sensor) plane, not from the front of the lens. Typical values for normal lenses are 50 to 80 cm. As focal length increases, so does this distance, with lenses in the 200mm range typically having 1 to 2m close focus distances. Lenses which can focus unusually close but which are not macro are sometimes labelled "close focus", though this practice is inconsistent. Lens Aberrations The perfect optical lens does not exist. The various imperfections are termed aberrations and fall into various defined categories. The most important of these are distortion, spherical aberration, coma, field curvature, astigmatism, and chromatic aberration. There are further "higher order" aberrations that actual designers need to be aware of, but which consumers rarely mention. Distortion describes the deviation from the correct geometric representation of the subject. Barrel distortion occurs when the lines defining the rectangular frame bend outwards, objects hence becoming barrel-shaped. Pincushion distortion is the opposite: the centre of the lines bends inwards. In the digital era both of these can be corrected in post-production; indeed, many manufacturers now rely on this fact. However any digital correction reduces image quality and might require cropping the original image. Moustache distortion describes wavy distortion and is the most difficult to correct, since such is not a simple geometric operation. The next two aberrations are especially noticeable at high (open) apertures. Spherical aberration is apparent from a blurred (less-than-sharp) image, caused by a spread of light rays from an ideal point. This can be corrected by pairing a converging lens element with a diverging lens of less power. The combination will be still converging and the shapes and materials can be tuned to reduce this aberration. Coma is the unsymmetrical rendering of points of light, so that they appear to have a tail, like a comet. This is due to off-axis rays travelling through more (or less) glass than those that are on-axis. Field curvature describes when a virtual image is rendered onto a curved field rather than a flat plane. This curve is typically concave, curved forwards at the edges relative to the centre. Designers specify this with a positive Petzval sum. But in certain telephoto designs the focus field is convex (a negative Petzval sum). Astigmatism describes how one set of parallel lines is out-of-focus compared to another set. This is especially noticeable at low (closed) apertures. In radial astigmatism, circular lines are blurred progressively from the centre of the image. In tangential astigmatism, radial lines are blurred. It is not possible to fully correct for both field curvature and astigmatism; this is always a compromise. Higher order problems include oblique spherical aberration, seen as a symmetrical light fringe. Unlike spherical aberration this increases with distance from the centre of the field. Newton’s famous prism demonstrated that white light could be separated into different hues, each of which represents a different frequency band. This experiment demonstrated that light frequencies bend to different degrees when travelling from one medium to another. This dispersion produces several problems grouped under the heading of chromatic aberration. Achromatic lenses correct this for two of the three additive primary colours, whereas apochromatic lenses correct all three colours. However, these names do not indicate the degree of correction, and should be treated with scepticism. Axial chromatic aberration (CA) is visible as colour fringing (often called “purple fringing”) in areas of high contrast. Lateral chromatic aberration (LCA or LoCA) is seen as colour changes within the depth of field, the blue end of the spectrum being either closer or distant, depending on the type of aberration. The effects of diffraction must now be noted, even though this is beyond the control of lens designers. As the lens is stopped down, the effects of light bending at the aperture becomes increasingly evident. This unavoidable effect (not a lens aberration) reduces sharpness at low (closed) apertures. In this regime aberrations become less important than diffraction itself. Decentring describes when elements are shifted from the perfect axis through the lens. This produces skewed images, exacerbating one or more of the above problems. Decentring is typically due to either manufacturing defects or damage over time.
Lens Design References
This article will provide further reading for those interested in pursuing the subject further. My primary reference for this series is the classic compendium Photographic Optics by Arthur Cox, who designed lenses for Taylor, Taylor, & Hobson (Leicester, UK) before moving to Bell & Howell (Chicago, USA). First published in 1943, this book was revised through the fifteenth edition in 1974. This is an essential book! Historical information was taken from Rudolf Kingslake’s A History of the Photographic Lens, which is an entertaining read for camera obsessives. He provides biographical sketches for each of the main players, illustrating their relationships and collaborations. There are any number of technical reference books for lens design. Of these Kingslake and Johnson 2010 and Sasián 2019 were consulted. Though I chose to keep the scope within my knowledge bounds! Optics soon gets into heavy mathematics, a field in which I am out of practice. So I will mention only one research article, by Jonas and Thorpe, since it contains intriguing information from the Leica camp. Information on the Zeiss naming schemes was gleaned from the series of articles by Hubert Nasse. Unfortunately he never wrote the article on Sonnar. Further information has been gathered from individual lens sheets, Zeiss being particularly generous about providing these. If only other manufacturers shared information as an open and free resource! Care should be taken in consulting any internet source since these are rife with errors, repeated from source to source without correction. Two lens databases are sometimes useful for determining details of consumer products: Sergei Borodin’s allphotolenses and Evgenii Artemov's lens-db. But even they will disagree on simple things like the lens formula. For the sake of readability I have not included citations. Works Referenced Cox, Arthur. 1974. Photographic Optics: A Modern Approach to the Technique of Definition, fifteenth edition. London: Focal Press. Jonas, Reginald P. and Michael D. Thorpe. 2006. “Double Gauss lens design: a review of some classics,” Proceedings of SPIE 6342, International Optical Design Conference 2006, doi: 10.1117/12.692187. Kingslake, Rudolf. 1989. A History of the Photographic Lens. London: Academic Press. Kingslake, Rudolf and R. Barry Johnson. 2010. Lens Design Fundamentals, second edition. Burlington, MA: Academic Press / SIE Press.Sasián, José. 2019. Introduction to Lens Design. Cambridge, UK: Cambridge University Press. Zahorcak, Milan. 2007. “Evolution of the Photographic Lens in the 19th Century,” in The Focal Encyclopedia of Photography: Digital Imaging, Theory and Applications, History, and Science, fourth edition, ed. Michael R. Peres. London: Focal Press, 157-76.