why are there no 17.5mm movie cameras?

Post by **contactprint** » Wed Dec 22, 2004 11:23 am

Hi everyone,

I'm a still photographer poking around and looking to try small gauge movies. 8mm is probably where I'll start, but looking at film costs and the films that are available it seems like there should be a 17.5mm camera or a duplexing 35mm (17.5mm run through once then reverse the roll and shoot again on the other half, split the roll after processing). 100 foot bulk 35mm is available in tons of different emulsions and speeds at really cheap prices.

I can only see one camera from around 1898 that used the straight 35mm sprockets for a 17.5mm format. There were some altered sprocket 17.5mm cameras from the 1930s as well. What gives? This seems like an obvious exercise in film economics and availablility compared to 8mm, not to mention increased film size at a similar price. Have I missed something? Do these cameras exist in some obscure place? Is there any way to build or modify a camera to take the readily available 35mm in a split 17.5mm format--perhaps by modifying one of the 16mm cameras or even a 35mm?

Thanks for helping a newbie,

Jarred

Post by **S8 Booster** » Wed Dec 22, 2004 11:54 am

Size Ã‚Â´n Price?

R

Post by **Carlos 8mm** » Wed Dec 22, 2004 12:39 pm

Interesting idea, specially when you can get very cheapo Svema film from Ukraine in raw stock.

The 17.5 frame size is a little bit greater than 16 mm (close to 12 x 9 mm instead 10.41 x 7.21 mm). But take in account that "half 35mm" is not so efecctive format than 16 mm or better, 9.5 mm. The wide where the perfortions are dispossed is close to 5 mm and the wide of the perforations is too wide for a "small format" as 17.5 mm.

The same happens with Standard 8mm. Perforations have the same wide as the 16mm ones.

I could bet for 9.5 mm. ItÃ‚Â´s the more efficient film format. (approaches the 70% of the film surface).

Dunno, splitting 35 mm is easy. If you can get 35 mm film stock at low prices than 16mm proportionally, just go for it!

Carlos.

Post by **jean** » Wed Dec 22, 2004 12:50 pm

My guess: mask off the filmgate, then flip the spools just like reg 8mm. Now the inconvenience is that you have to hold the camera horizontally if you don't want a fancy portrait mode. Slitting it should be no problem, when the final product is video probably you can just telecine it and do the "slitting" in post. Sounds like a fun project, some old 35mm arris show up at ebay and end up cheaper than sought after super8 models or 16mm cameras. Zooming should look funny, but probably there are no zooms for affordable 35mm cameras anyway.

But then the average 35mm camera is huge and heavy if you don't like the small arris. Film spols are also huge, the flipping is inconvenient as hell. But you could prpeare a bunch of magazines and flip the spools in a quiet moment.

I don't kow how much film, processeing and telecine is, since I never bothered for 35mm film, and if the gained estate is worth it compared to 16mm.

Post by **mattias** » Wed Dec 22, 2004 1:18 pm

why not just shoot 2-perf instead? sure, the camera/conversion is probably a bit more expensive, but there are several labs and post houses that are equipped to handle it already and you'd use the same amount of film.

/matt

Post by **Carlos 8mm** » Wed Dec 22, 2004 1:28 pm

May be this help:

http://www.sci.fi/~animato/filmhist/filmhist.html

Carlos.

Post by **Carlos 8mm** » Wed Dec 22, 2004 1:38 pm

mattias wrote:why not just shoot 2-perf instead? sure, the camera/conversion is probably a bit more expensive, but there are several labs and post houses that are equipped to handle it already and you'd use the same amount of film.

Yep, that was the original 17.5 mm format. Each frame have 2 perforations (from the original 4 of 35 mm frame). Shooting the film horizontally allows to get a greater frame (close to 18 x 12 mm) but shooting the film vertically to get a 12 x 9 mm is fine, specially if you want a little format and save money.

Carlos.

Post by **Herb Montes** » Wed Dec 22, 2004 2:02 pm

The reason there are no 17.5mm movie cameras around today is because when Kodak was developing a format for home movie use they did not want to use highly flammable nitrate film which much of 35mm was manufactured from at the time. When they developed safety base they settled on 16mm wide film so as to not make it economical to slit 35mm for 16mm cameras. Also the reversal porcess they developed cut the cost of making movies since you did not need to make a positive from a negative as was neccessary with 35mm. Many early 17.5mm cameras could also be used to make prints and even project movies. The advent of 16mm and 8mm meant seperate camera and projectors for home movie makers though there were a few cameras around that could do both.

Interestingly enough the man who brought us the Bolex first created a 35mm movie camera that could print and project movie films, the Bols Cinegraph. Since 16mm was more economical and popular he modified his design to accept the new format and the Bolex camera was born.

Post by **Carlos 8mm** » Wed Dec 22, 2004 2:36 pm

BTW,
how many minutes can be filmed at 24 fps with 100 ft of 35mm film? Maybe one minute?

Carlos.

Post by **jussi68** » Wed Dec 22, 2004 3:03 pm

mattias wrote:why not just shoot 2-perf instead?
/matt

Do any of the swedish post houses do it? Which cheapo cameras are the easiest to convert to it?

Post by **mattias** » Wed Dec 22, 2004 5:04 pm

jussi68 wrote:Do any of the swedish post houses do it?

i'm not sure. i never got that far in my research (i don't know if you remember this but there was a thread about it a while ago). i think it's a standard configuration on many telecine machines (they use continuous film transport so it's just a software thing), although you may not get proper edgecode without extra options, which could complicate negative cutting. it wouldn't be hard to find the codes manually from pal tc though by just looking at the punch frames.

Which cheapo cameras are the easiest to convert to it?

any old arri should convert fine. i think most converted ones i've seen/heard about have been 2c's.

/matt

Post by **downix** » Wed Dec 22, 2004 5:12 pm

Bell and Howell actually developed a 17.5mm movie camera, but quickly changed it to 16mm when Kodak introduced that standard. It is known as the Filmo. You can see its 17.5mm roots if you measure the pressure plate on the early type 70's like mine.

Post by **contactprint** » Wed Dec 22, 2004 5:45 pm

Thanks for all of the great replies so far. Here's a brief follow up:

Film price - from http://www.bhphoto.com/
50' super8 tri-x reversal = $13.95
100' tri-x negative (I believe this is the same emulsion with a slightly darker base) = $32.95

If we split this into 17.5mm we end up at about $8.25 for 50'. Personally, I'd like to try some of the newer emulsions like TMax 100/400/3200. I'm thinking about a negative process, but FYI TMax 100 has a reversal kit available and has a very light base.

A couple of other films that might be interesting to try:
100' Fuji Velvia 50 (positive film, highly saturated colors, extremely high resolution) = $97.95
100' Fuji Provia 400 (positive film, pushes well to speeds like 1600+) = $114.95
150' Tech Pan (negative BW film, extremely high resolution, but very slow ISO 25 depending on developer) = $75.95
100' TMax 3200 (negative film, extremely pushable to very high speeds, big grain) = $106

I'm also curious about the time available on 100' of film. Carlos mentioned a couple of good frame sizes worth checking out: 18x12mm and 12x9mm. I don't know if there is any frame spacing like in still photography--i calculated these numbers assuming no frame spacing.

12x9 = 3386 frames 1 direction = 141 seconds @ 24 fps (but you still need to subtract any scrap film at the beginning or end of the roll), 188 seconds @ 18 fps--also you've only used half the film--flip it over and you'll get twice as much on 1 100' roll of 35mm

18x12 = 2540 frames 1 direction = 106 seconds @ 24 fps, 141 seconds @ 18 fps, plus the flip

I'm very green here. I haven't physically toyed with any reel to reel cameras, so I don't know how much modification is typically possible. I really like the idea of a general use movie camera that takes 35mm film (or split 35mm) which can be gate masked to various frame sizes, but I suppose there are certainly some technical problems to get around. For example, if you mask the frame to get a smaller frame size, I see two problems. First, the lens is no longer centered with respect to your new frame size. Second, you've got to adjust the film advance rate so you don't have gaps between frames. Hmmm... How close to the realm of reality is the idea of modifying one camera or another to use 35mm or 17.5mm? Would it be easiest or even possible to modify a 16mm camera for 17.5mm film or do sprocket issues totally prevent that? Are we forced to use and modify a 35mm camera because of sprocket issues?

Thanks again--I was really surprised to wake up to lots of great responses this morning.

Jarred

Post by **Herb Montes** » Wed Dec 22, 2004 8:01 pm

It might be possible to mask off the gate of a basic 35mm movie camera like an Eyemo or Konvas to shoot 17.5mm and flip the roll to shoot the other side (like it's done with double regular 8mm), after convertting it to 2-perf pull-down. And then slit the results after processing. Projecting the film is another thing or have it transfered to video. You can find one of those old DeVry portable silent porjectors which show up on eBay (I got two of them) and modify it to run 17.5mm wide film.

There has been a discussion about Techniscope 2-perf conversions discussed on the Konvas owners group.

17.5mm cameras made in the silent era are rare collectors items. I think one showed up on Sam Dodge's site once. You could ask him about them.

http://www.samdodge.com

Post by **Actor** » Thu Dec 23, 2004 1:59 am

Carlos 8mm wrote:BTW,
how many minutes can be filmed at 24 fps with 100 ft of 35mm film? Maybe one minute?

Carlos.

One minute, six seconds.