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stop motion single frame fps


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#1 Christine Elfman

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Posted 05 October 2010 - 01:07 AM

I am making a stop motion animation film using my great grandfather's Keystone Olympic K-32 double 8mm camera. I am wondering if the Frames per second setting is exact when using the single frame trigger for stop motion. I cannot perceive a difference when I pull the single frame trigger at either 12 fps or 48 fps. Is there a standard default frames per second that the single frame trigger corresponds to? Or are the same fps adjustments applicable to the single frame trigger. This camera is a wind up camera, and does not maintain constant speed throughout the time it unwinds / films. I am wondering what the effective shutter speed will be for the single frame setting in order to base my lighting / exposure. I am new to motion picture making. Coming from a background in still photography, it took me awhile to understand the rotary shutter's relationship to exposure. This camera's shutter angle is about 172 degrees.
Thanks for your consideration!
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#2 Alessandro Machi

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Posted 05 October 2010 - 02:24 AM

This is an excellent question as some cameras will default the shutter speed setting in single frame mode to whichever position the actual frames per second that the camera set to.

In theory, you should hear a difference between 12 and 48 frames per second when using the single frame mode if the camera is actually defaulting to the frames per second speed setting that the camera is set to.

However, there could be some kind of additional default that ignores both the 12 and 48 frames per second speed settings. I wonder if researching how bolex does it might give you an additional way to figure this out.

You might be able to detect a difference in the shutter speed movement by looking through the lens while the camera is running, if so, then compare that to how it looks when in the single frame mode in both speed positions.
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#3 Brian Rose

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Posted 05 October 2010 - 10:49 AM

I've worked in 8mm and 16 formats, and shot quite a bit of stop motion animation, and to be brutally honest, I think you need a different camera. Why?

1) As you said, there is the issue of whether a single frame is the same when the camera is in 48 FPS mode, or 12 FPS. Considering the simplicity of the inner works of these cameras, which were designed for the consumer, it is likely that single framing does not override the frame rate. If we apply the formula for shutterspeed to this situation 1/((FPS * 360)/Shutter Angle), your shutterspeed varies from 1/25 to 1/100 for 12fPS and 48 FPS, respectively. That's a variance of as much as two stops!

Worse still, since this is a clockwork camera, as the wind goes down, the speed varies unpredictably. Some, more sophisticated cameras like the Bolex has a governor that would shut off the camera as it wound down so the FPS was consistent. But yours, when the wind goes down, so does the speed, so really you might not be able to predict exposure depending on how wound up it is. And you can't really keep winding the camera as you shoot, because it will move the camera and disrupt the fluidity of the animation.

Another issue which you didn't mention, but I think is important, is the viewfinder. Your camera is a non-reflex, so your viewfinder is just giving you a best guess as to your framing, and there is inevitable parallax. This is fine for most situation, but in animation where everything is in close quarters, framing is crucial. Not to mention, there are focus issues in play; unless your lens has been collimated, its hard to say if the focal length is accurate with a tape measure, and it is safe to be able to see what is actually coming through the lens.

And since double 8 is essentially a dead format, your only source is either old, unused rolls that come up on ebay, or buying from somewhere like Pro8, which takes 35mm film and cuts & resprockets them into double 8. Then you have to find a lab capable of splitting the film and processing it. I'm not sure many are left. All this will cost you more than if you just went for Super 8.

My advice is find a different camera. Start with a Super 8, which are VERY affordable, and don't have the issues I described because they come battery powered, and have more sophisticated optic. Heck, everyone has an aunt or uncle with one of those cameras in their attic, so if you dig a bit, you might be able to get one for free.

Your Keystone camera, as much as it pains me to say, belongs on a bookshelf, because about all it's good for now is display. You can certainly try to shoot with it, but it's gonna be a lot of headaches, and more costly than Super 8.

Best,

BR
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#4 Jim Carlile

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Posted 06 October 2010 - 01:29 AM

I don't quite understand the question. If the camera has a single frame setting, then it will be single frame no matter what speed the camera was set on-- because now it's set on single frame.

So it's one frame per however many times you pull the trigger. As to the shutter speed, with that camera it will be approximately 1/60th of second at the single frame setting.

This camera will be fine for stop-motion-- just make sure you compensate for the parallax difference bwteen lens and viewfinder.
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#5 Brian Rose

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Posted 06 October 2010 - 11:22 AM

Jim, I gotta disagree here.

The parallax can be compensated for, sure. But together with the issues of exposure, focus, the clockwork mechanism, all on top of the fact that the camera employs an all but extinct film format which is now only custom made all seems to be a recipe for an unneeded headache, especially when all these issues can be resolved in one fell swoop by switching to Super 8. And she'll save some money too.

BR
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