The Exposure Triangle

Wait… (checks the url) did I accidentally go to photrio? 🤔

Thanks for the clarification. Was never a film guy myself ...

Thanks! I don't know anything about film sizes, but it's quite interesting to me regardless. Hope it's okay if I ask a slightly related question:

My favorite series of lenses is one which was supposedly used in several kinds of minilabs/professional processing machines. They were made in a range of focal lengths and all of them are labeled with a number, which I suspect might indicate the film sizes they were used to process. There are the following:

E18C - in focal lengths of 35 and 40 mm (which might correspond to the 18x24 mm format)
E36C - in focal lengths from 48 to 100 mm (probably for the 24x36 mm format)
E66C - in focal lengths from 75 to 94.1 mm (?? - I thought perhaps made for max. 6x6 cm format, if that's a thing which was processed in such labs?)
E90C - in focal lengths from 105 to 125 mm (?? - any idea?)

There's no definitive proof of that theory being correct, but if we assume that the number has to do with the format they were designed for, I would really be interested in your thoughts. I can try to measure some of the image circles of the lenses in question, which could probably give a good indication of the possibilities.

I'm grateful for any help, because there certainly doesn't seem to be any documentation left on those devices in question or at least it's incredibly hard to find.

FT-2, fotoapparat Tokareva (Fedor Tokarev, better known for his semi-automatic pistol), 24x110mm on 135 film, about 17 thousand cameras manufactured. Gorizont (Horizon), 24x58mm on 135 film, about 50 thousand cameras.

If I know Leica was the first still camera using 35mm cine film in 24x36mm format. This is quoted from en.wikipedia.org/wiki/Leica_Camera :

"The first 35 mm film Leica prototypes were built by Oskar Barnack at Ernst Leitz Optische Werke, Wetzlar, in 1913. Some say the original Leica was intended as a compact camera for landscape photography, particularly during mountain hikes, but other sources indicate the camera was intended for test exposures with 35mm motion picture film.[5] The Leica was the first practical 35 mm camera that used standard cinema 35 mm film. The Leica transports the film horizontally, extending the frame size to 24×36mm with a 2:3 aspect ratio, instead of the 18×24 mm of cinema cameras, which transport the film vertically.

The Leica had several model iterations, and in 1923, Barnack convinced his boss, Ernst Leitz II, to make a preproduction series of 31 cameras for the factory and outside photographers to test. Though the prototypes received mixed reception, Ernst Leitz decided in 1924 to produce the camera. It was an immediate success when introduced at the 1925 Leipzig Spring Fair as the Leica I (for Leitz camera). The focal plane shutter has a range from 1/20 to 1/500 second, in addition to a Z for Zeit (time) position."

Tomioka Optical.
They have several lenses in each range. E36C series, for example, includes 55, 80, 86mm lenses.

Thanks a lot for that information - that's very interesting. Will have to look up how to check if those values are realistic for the respective lenses I own. I'm sure there are some tutorials on how to measure image circle... if you know some easy ones, please let me know!

Indeed. Tomioka surely was the manufacturer of a majority of those lenses. Many are labeled "Tomioka" or "Tominon" after all... It's not clear though, if they were also responsible for the lenses, which are only labeled "Copal" and "EXXC" (18, 36, 66, 90). As far as I know Copal produced lenses themselves and they also had other suppliers, as I've learned from some conversations with a person who worked there.

As far as I remember, ExxC ('C', fixed aperture around 12 .. 14mm, depending on the focal) series are Tominons (Tomioka/Copal M39, Noritsu M42mm), designed in collaboration ("technical alliance", leading to "consigned mass production") with Zeiss.

Oh - wow! Didn't expect that kind of information... thank you so much! So all of these are likely Tomioka made as well?

I knew about the Tomioka manufacturing connection to Zeiss (Contax/Yashica) but I wasn't aware of the fact that it extended to a certain degree to the industrial lenses they made as well.

What do you mean by "Noritsu M42"? Do some of those lenses exist in a different mount for Noritsu machines? I'm in the middle of finishing an article on Noritsu (another series of lenses I'm very interested in) and while I have seen quite a few, I've never been able to discover a single EXXC lens actually labeled Noritsu, nor have I found one with a M42 mount. All the fixed focal length ones I own have a 40x0.75 mm mounting thread, like the excellent 32 mm f/4:

Robert OToole has pretty definitive proof though, that some of those lenses were used in Noritsu machines, so it wouldn't surprise me if lenses like that existed.