The clever camera code on rolls of film [video] | Hacker News Reader

The clever camera code on rolls of film [video]

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111 pointsTomte27 comments

While not something that is read by a mechanical process - the code notches on sheet film https://125px.com/docs/unsorted/kodak/f3.pdf

This is for being able to touch and orient while in the darkroom.

[PDF]

edit: someone downvoted me for leaving a helpful comment. Nice.

One forgotten fact about film manufacturing was that Kodak provided employment opportunities for people who were blind in their fully dark film plants.

I can imagine the notches in the parent post as an innovation that came from a blind employee.

(1) https://collections.museumsvictoria.com.au/articles/13677

Well, guess where the opportunities lie these days? Secure document destruction! It's true; I don't know if there are for-profit operations with blind employees, but there are definitely non-profits with blind volunteers who destroy corporate documents very securely!

Why would someone volunteer to destroy corporate documents for free?

It isn't free, it's just at basically a zero-profit margin by design and intent.

Non-profit does not preclude people getting paid for work they perform.

> there are definitely non-profits with blind volunteers

This phrase implies that the blind people aren't getting paid. If they were, they wouldn't be "volunteers".

Because people volunteer for non-profits? I agree that destroying documents is a pretty tedious job, but some people just want to help out their favorite organization, and would volunteer for a lot of tasks you or I wouldn't want to do.

Very handy when I've forgotten what film I've loaded into what carriers!

I used to own a Bronco SQ-Ai 6x6cm roll film camera. This camera had removable backs so that you could fairly easily switch between say 64 ISO slide film and 400 negative film mid roll. To be able to do this, each film back had two dials on it: one for ISO and one for exposure compensation. When you attached the back to the camera, the information was communicated by a set of contacts to the metering prism. There is something so delightful about that window of time when cameras were becoming electronic but still using film. So many clever things were happening. I think about the Canon T90 that the presenter in this video mentioned: it was a technical marvel with lots of different metering modes, a digital display, etc. ...or cameras like the Rollei 6008, which had incredibly sophisticated light metering and film handling, yet still used an analog waist level finder.

FYI, Bronica. And the fun detail about the ISO and exposure compensation is I beleive they were concentric dials (they are on my Bronica GS-1) so they were just adjusting a single contact. In other words, ISO 100 with no compensation is the same value as ISO 200 with a +1 stop compensation.

Bought a Canon EOS-3 year ago and it's funny how it almost feels like DSLR but with film. The amount of electronics and what in can do is amazing. Well DSLRs are basically film SLRs but with a sensor instead of film + some R&D improvements throughout the years. Also DSLRs got the back display which is a lot more better than the configuring late-90s SLRs with some weird function button setups with super small display on top of the camera. If my memory serves me right the last pro camera, EOS-1V had some serial link cable and a desktop software to configure things properly and get the exposure data for the film rolls. Like exif data but before exif data :D

DX coding was a clever solution for sure. As a longtime camera collector and film photographer, however, I shake my fist at manufacturers who made cameras that could read only a few DX codes, e.g., 100 and 400, and for films with other DX codes would set the camera to ISO 25 or something useless like that with no way to manually adjust ISO on the camera.

The video talks a bit about that; some cameras saved on cost by only reading one or two of the "patches", and would set a "close enough" ISO.

In practice (at least the video claims), this often shouldn't be a big deal, as most film is tolerant to the over/under-exposure you'd get by setting a few ISO levels off from the correct one. For low-end consumer cameras where you'd expect the user to only use 100-, 200-, or 400-speed film, I think that's a reasonable trade off to make. And it's a low-end camera; people who buy them are expecting some corners to be cut that might reduce quality.

Also consider that a manual selector would probably have been more expensive to integrate than adding the rest of the hardware needed to detect all possible ISO levels. So if they didn't want to even spend money on the latter, they certainly wouldn't on the former. And the kinds of people who would buy cameras like that are probably also of the kind who would forget to manually set the camera to match their film, or wouldn't even understand that they need to.

But yeah, if some of those cameras were doing "can't read, so set to ISO 25", that's just dumb.

The comments about tolerance for underexposure only apply to print film, not positive film. But no self-respecting transparency shooter would bother with such a camera...

This is one of those channels I stumbled upon, and figured I would watch one and move on. Nope. Super fascinating channel on stuff I never knew or thought, how it worked.

DX codes are a huge pain these days as a lot of new rolls of film, especially B&W don't have them, leading to a frustrating situation on cameras which won't allow you to manually set ISO (which is a huge number of sub-professional cameras).

This is what the end of the video is about, and there's even a reference to an available solution.

Which B&W stocks don't have them? Every B&W canister I've ever bought from Kodak, Fuji, and Ilford is DX-coded, and even the smaller manufacturers (like Foma) have them. The only B&W stock I've seen without a DX code is Astrum (which has come in a cheap plastic can every time I've bought it).

most of the small manufacturers--Ferrania P30, all the Foma films, I believe the Adox films as well. The Rollei films have DX, and like you said--Kodak, Fuji, and Ilford.

As the video points out, the big players mostly still DX code all their film, but many of the smaller, indie (or low-end) producers don't.

Technology Connections has a whole series of videos on film and analog cameras.

Totally recommended. I knew it would be him by the domain, title and topic of the submission alone.

The DX codes on the edge of the film strip aren't as well known as canister DX codes but contain more information. They were very useful when I was scanning old negatives.

Reminds me of people who used VHS to make backups.

How is that relevant? DX codes aren't about storing arbitrary data or backups, it's a system for providing basic information on the roll of film itself.

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