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How did old cameras know what film roll we loaded inside? (film, 17 minutes)

Technology is undoubtedly one of the most vital fields that not only changes our lives but also brings new solutions to various aspects of daily life. In the latest episode of the "No Effort November" series on the Technology Connections channel, the author delves into the history of film photography and its evolution concerning increasingly automated processes in photography. Right from the outset, the video introduces viewers to the topic of traditional film, as well as how its different ISO levels impact image quality. Faster films allowed for shooting under challenging lighting conditions, but they came with the risk of producing grainy images. Therefore, while automation became key, certain elements still required ongoing user effort.

The author highlights the development of coding systems aimed at simplifying the film utilization process. He explains how DX technology, introduced in the 1980s by Kodak, automatically adjusted camera settings to match the given film, eliminating the need for manual setting of film speed by photographers. This is particularly interesting for any photography enthusiast as it expedited the process of taking pictures and minimized the risk of errors when loading film into the camera.

As the material progresses, the author discusses in detail how DX encoding operates. Specifically, he covers how cameras recognize specific films through electrical contacts and markings on the film cassette's surface. Viewers can understand that the more professional the camera, the more information it can read, which benefits using films with varying sensitivities. However, in the context of some cheaper models from the 80s and 90s, the lack of manual ISO setting could become a problem given the declining availability of films without DX encoding.

To conclude, amidst the tumult in the world of analog photography, Technology Connections also presents modern solutions like DX coding stickers that allow the use of unmarked film in cameras lacking this feature. This is an excellent example of innovation reflecting creativity in technology. Additionally, the author notes that as of the time of writing this article, the video has garnered 989910 views and 52518 likes. As evidenced, the subject holds great popularity among photography enthusiasts, and each new solution captures viewers' attention.

Toggle timeline summary

  • 00:00 Introduction to No Effort November.
  • 00:17 Overview of traditional film photography.
  • 00:24 Explanation of different film types and sensitivity.
  • 00:39 Importance of film speed in photography.
  • 00:49 Faster films suitable for low light conditions.
  • 01:01 Effects of using faster films on image quality.
  • 01:30 Cameras automatically handle exposure settings.
  • 01:57 Need for a no-effort film loading process.
  • 03:55 Introduction of DX encoding for 135 format film.
  • 04:19 How DX encoding simplifies film handling.
  • 04:52 In-camera auto-sensing capabilities.
  • 06:21 Professional cameras can read encoded information.
  • 06:39 Consumer cameras designed to read DX codes.
  • 08:35 Encoding strategy for various film speeds.
  • 09:00 Implications of messing up exposures.
  • 10:34 Cost-cutting measures in low-end cameras.
  • 12:30 Adoption of DX encoding by film manufacturers.
  • 12:56 Issues with older cameras lacking DX compatibility.
  • 14:21 Workarounds for using older cameras with non-DX film.
  • 15:26 Conclusion and summary of the video.

Transcription

Every year, we go through this. Every year. I tell you, it's No Effort November, but you just… you don't believe me! I… I don't know how we got here, but um… Let's try again. Hello, and welcome to No Effort November, a series of videos for the month of November in which no effort is made. Before digital cameras were a thing, you had to buy this film stuff to take pictures. This film was available in a bunch of different varieties. The sensitivity of the film to light, or its speed, was one of a few factors you'd consider when buying film. Faster films like ISO 800 were good for action shots since the camera could use a faster shutter speed and prevent motion blur. They were also good for lower light situations, making photography possible when it might otherwise not be. But faster films produced a grainier image, so if image quality is what you were after, you might have wanted to use a slower film like ISO 100 or even 50. Now because changing the film's sensitivity to light will change how the camera needs to expose it for a given scene, cameras featured a setting for film speed. In manual cameras, this would usually just change how its light meter responds to light. But those were mostly used by professionals, and consumer cameras from about the 1960s onward would handle exposure automatically. But that can only work if the camera knows the film speed, so you had to match the camera's speed setting to the film you were putting into the camera. That sounds like effort, and if you forgot to change this when you put in a new roll of film that was a different speed from the last one, all the images on that roll would be under- or overexposed, and wouldn't that be embarrassing and or devastating. Clearly, we need to make this a no-effort process. There were many potential ways to do this. For instance, we could come up with a new kind of film cartridge that could communicate its speed to the camera through some sort of physical means, like maybe the longer a little sticky-outy bit is, the faster the film is inside. But, despite Kodak's best and repeated efforts to come up with a more convenient film product, the venerable 135 format consisting of 35mm film, essentially the same stuff used in the movie business, spooled and encased in a simple round cassette with a light-proof tangential exit slot so it can poke out like a weird tongue, just would not die. A big part of this was likely due to the fact that camera manufacturers had made the process of loading 35mm film much easier with time, which largely negated the benefits of self-contained film cartridges like 126 or 110. This Ricoh FF3-AF Super, for instance, is an automatic point-and-shoot camera design dating from 1982. And it features easy film loading. Look, there's film in here, OK, I'm not going to open it to show you, but it's just plop the cassette here, pull the film out of it and up to a little orange mark inside, close the back, and press the shutter button. The camera will load it automatically. In addition to auto-loading, the camera also features auto-focus, auto-exposure, a built-in flash. Really, this is a very competent point-and-shoot camera, but you still have to set the film speed manually with this control on the front. Luckily, by this time we had little windows on the camera back that let you see a portion of the film cassette where it would usually list its characteristics, and also so you could tell if it was, you know, if there's film in there or not. But you could still screw this up and ruin an entire roll if you weren't just a bit careful. So, in 1983, almost 50 years after it officially became a format, Kodak would introduce DX encoding to 135 format film cassettes. DX, for Digital Index, served to make film handling easier for both the photographer and the photo finisher. It did this in three ways. First, this barcode on the cassettes identifies the specific film emulsion inside, and film processing equipment which could read this barcode would automatically determine developing times and ensure a roll of film wasn't about to go through the wrong development process. Secondly, DX encoding was also present on the film itself. Once developed, film edge markings and barcodes, exposed onto the film when it was packaged, also identify the film stock, which could be used in printing and scanning equipment for automatic color correction. Additionally, it encoded the frame numbers, which was useful when ordering reprints and whatnot. But the third and final part of DX encoding is, to me, the most interesting. DX camera auto-sensing would finally make loading a camera a, mostly, no-effort experience. Here, take a look. This is my Canon T90, and when I insert this roll of Kodacolor 200, it knows that's ISO 200 film. Stick in some Cinestill 50D, and it registers as ISO 50. This Fujicolor Superior 400 shows up as ISO 400. And this roll of Pro Image 100 registers as, you guessed it, 100. And apparently those are the only four speeds of film I ever buy. The camera determined the film speeds by using electrical contacts to read a series of patches on the surface of the film cassette. These patches can be shiny and electrically conductive, or covered with an insulating layer of black ink. There are two rows of six patches across the cassette's length. However, only five patches per row encode data. The five bits along the top row encode the film's sensitivity, and the bottom row is split into a 3-bit section which encodes the number of exposures on the roll, and a 2-bit section which defines the film's exposure tolerance. That's how wrongly you can expose it before it affects the captured image. This simple arrangement, when detected and decoded by the camera, will tell it all it needs to know for automatic operation. Now this is a professional camera, and as such it's capable of reading most of the encoded information. It will even rewind the film on its own when you shoot the last frame. However, it doesn't read the film's exposure tolerance. Frankly, I don't know how much help that would be for any camera to know outside of weird edge cases, uh, but anyway, not everybody has a professional camera, and Kodak knew that. So when they designed this code scheme, they arranged the information so that a cost-cut consumer camera could set itself correctly for any speed between ISO 25 and 3200. This Yashica Samurai, for instance, is… a very weird camera, don't worry too much about that. This is a half-frame SLR from 1987. Uh, it's definitely pretty high-end, but also definitely still a consumer camera. And we'll see that in the film compartment, there are only four contacts compared to the T90's eight. Actually, the T90 has 16. Canon used a pair of contacts for every bit of the code it could read. Which is weird because, like, the cassette is metal and it was designed so that the two patches closest to the spool post are always bare. That's why they don't convey information, they're just a ground plane, and the camera only needs to check for continuity across that ground and a single contact point at each bit location. The T90 doesn't use the ground, and instead reads every data bit location individually. I don't know why Canon overcomplicated this. But anyway, the Samurai, with its four contacts, one of which is ground, is only checking the first three bits of the first row. That's all. That gives us eight possible combinations, which might not seem like enough, but by the time DX encoding was a thing, consumer films were generally sold in doubles in speed, with 100 and 200 being perhaps the most common films, 400 pretty common but less so, 800 your sports action film, and 1600 being pretty exotic. And see, even though we only have three bits representing eight combinations, we can start at 25 and through doubling get to 50, 100, 200, 400, 800, 1600, 3200. That's eight. Kodak smartly used bits 4 and 5 in the 5-bit code to distinguish the weird in-betweeny speeds like ISO 160, 64, or 1000. Speeds that pros might use with regularity, but casual photographers were unlikely to run across at the grocery store. This website I found has a chart of all the combinations, and we'll see that the first three bits are identical across three speeds, and only change at the next whole stop in sensitivity. That makes bits 4 and 5 essentially irrelevant for consumer cameras. And here's the other thing. If you mess up an exposure by a third of a stop, it doesn't really matter. Print film, especially, has amazing exposure latitude, and so really if you were to expose an ISO 1000 film as if it were 800-speed film, you wouldn't notice. Slide film needs exposure to be pretty on-the-nose, so it's harder to get away with this. But negative film is generally very lenient. These films are all coded as having plus-3, minus-1 sensitivity, so you can screw up exposure by a full stop in either direction and be fine. ProImage 100, interestingly, can only take two stops of overexposure. The weenie. Oh, and while it might be nice for the camera to know how many exposures are on a roll of film, well, it's not exactly critical info. There's little point in complexifying a point-and-shoot consumer camera to that extent. You're just gonna shoot till you get to the end of the roll, then hit rewind. Plus, most of the time you could squeeze another exposure or two out of a roll, so you wouldn't want the thing to rewind at the end, anyway. And thanks to PrintFilm's generous exposure tolerance, particularly with overexposure, some other camera manufacturers would cost-cut even further and only look for continuity in one spot. This Minolta Memory Maker 2000 is a cheap little plastic camera that my parents got me when I was… maybe 8? I was young enough to go nuts with a blue Sharpie at one point. Um, anyway, look inside its… backwards film compartment, that's distressing, and you'll find there are only two contacts pressing on the third and fourth bit. If we go back to that chart I found, we'll see that those two patches are never connected together until we get to ISO 400, after which point they remain connected for 800, 1600, and 3200 speed film. So basically, if these contacts aren't bridged, which would be the case for any film less than 400 speed, the camera treats whatever film you put in it as if it were maybe ISO 100. You probably won't notice, at least with PrintFilm, because of the exposure latitude. But if you load 400 or 800 speed film, well now it knows you got some fast stuff in there! It'll have to, like, speed up the shutter a bit. I would guess it probably just treats everything fast like 800 speed, deliberately underexposing 400 speed film by a stop to get faster shutter speeds. And hey, as imprecise as this is, this did indeed work decently well. Its terrible plastic lens meant the images never looked that great, but they were exposed correctly. If you should happen to find ISO 500, 1000, 2000, or 4000 film, though, they'll get wildly overexposed in this camera. I don't think Kodak intended the DX code to be used as this camera uses it. I'm pretty sure this is what you might call a hack. As time went on, all of the film manufacturers got on board with this encoding scheme. From Ilford, to Fuji, to Kodak, to… others probably, you could eventually expect any new film cassette to have these little boxes on them so your camera knew what it was. And now, this is becoming a bit of a problem for many cameras from the 80s and 90s. See, lots of cameras, including this Yashica Samurai, have no ability to set the ISO manually. When they were new, you could easily ask, why would you want that? But now that film photography is the niche hobby it is, well there are plenty of films available which don't have DX encoding on their cassettes. The big guys like Kodak, Fuji, and Ilford are still making new film cassettes with full DX compatibility, and luckily the folks behind Cinestill are also sourcing proper cassettes. But other less expensive options like Freestyle's Arista.edu line of films… well, they're missing it. There are also an increasing number of sort of indie films out there in small production runs which often reuse cassettes. Which to be clear, is a really cool idea. But they'll be forced to cover up the DX code on whatever cassettes they get their hands on, because it will usually be wrong. We are also starting to see plastic film cassettes, which can't rely on the cassette itself to be a common ground… wait, was Canon thinking that far ahead? Uh, there has also always been the option for frugal folks to bulk-roll their own film into reusable cassettes like these. My Canon T90 has a button to select the ISO when it can't read the DX code, but the Yashica Samurai… well, if it doesn't see a code it'll just default to 100 speed. That's not a bad strategy, necessarily, but it's still really annoying that I can't use this camera unless the film I want to use has a DX cassette, or just happens to be 100 speed. And I'm lucky that I was able to find documentation on what this will do with a blank film cassette. Loads of cameras from the 80s and into the 2000s might not have that info available. Luckily, if you want to use such a camera, you can now get DX code stickers. That's right, folks are making stickers now which are electrically conductive and in just the right spots to put onto film cassettes that are not DX-coded, specifically for making your weird 80s and 90s cameras work with weird film. I think the best use for these is when you're bulk-rolling film, as that adds significant expense to a film cassette you won't reuse, but it's nice to know that that option is out there regardless. Anyway, I think that's about it. Now look, I didn't whip out the slider for b-roll, I didn't do any research, I didn't even warm up the set before I started shooting this. This was a low-effort production, alright? I phoned it in. This was in my back pocket for years. Just one day I was gonna talk about this. Well, here we are. The video's made. Didn't take that long. Now go have your turkey or whatever. 🎶 ...was available in a bunch of different varieties, and well I screwed that up already. It was designed so that the two patches closest to the spool post are always bare. That's why they don't contain- 🎶 I did it again. Convey is the word I meant to say. UUUUUUUUUGH But, you could still screw this up and ruin a roll if you weren't just a bit careful. 🎶 I don't know why Canon oversimplified this. I said oversimplified? Are you kidding me? The word is overcomplicated, you massive dingo. Same stuff used in the movie business. Spooled and encased in a simple, round casse- 💩 Poop. 🎶