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Cinema vs Photo

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Tim Allen
Cinema vs Photo
on Jul 21, 2010 at 6:44:46 pm

So... I'm aware that the lens length for video is different than film, but I recently heard somebody talk about the difference between a cinema lens and a still photo lens. I guess I just assumed that since they were both used for 35mm image acquisition that they'd be the same. Are they not?

Specifically someone commented that a 50mm photo lens is the same as an 85mm cinema lens! Really? I don't really get that.

Would love some definitive clarification on this!

Thanks, gang!

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The Real Tim Allen
Tribal Iris | HD Production & Finishing


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Todd Terry
Re: Cinema vs Photo
on Jul 21, 2010 at 7:13:39 pm

It has to do with the frame size.

A 35mm still camera SLR and a 35mm motion picture camera both use exactly the same size 35mm film.

However, your SLR takes stills on the negative horizontally, whereas the cine camera takes each frame as the film travels vertically. Therefore, a still frame from a 35mm SLR is actually quite a bit bigger than a frame of 35mm motion picture film.

Ergo, the difference in the focal lengths and how they behave with each format.

But... a 50mm is a 50mm, no matter what the format. Is just that how each is perceived based on the format size. For example, on a 35mm SLR a 50mm would be considered a medium or "normal" lens. Put a 50mm on a 16mm camera and it's quite a longish lens.



T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Tim Allen
Re: Cinema vs Photo
on Jul 21, 2010 at 7:28:00 pm

Thanks, Todd.

That makes a lot of sense. So if I read you right, for those shooting video on DSLRs the lens length translates identically - for the most part - from cinema 35mm film cameras. Yes?

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The Real Tim Allen
Tribal Iris | HD Production & Finishing


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Todd Terry
Re: Cinema vs Photo
on Jul 21, 2010 at 7:58:36 pm

I depends on the sensor size.

All lenses of a given focal length have exactly the same field of view. One 50mm lens will have the same field of view as any other 50mm lens. Each would project the same circular image with the same field of view. It then becomes a function of the size of the sensor inside that total circle which determines what the field of view that the sensor captures (as opposed to how much field of view the lens actually sees).

For cameras with a 35mm cine frame size sensor (and I think that's the size for, say, a Canon 5D), the a 50mm lens on that camera would have the same field of view as a 50mm lens on a cine camera.

If a camera has a smaller-than-35mm-sized sensor, such a a Canon 7D or T2i, then that same 50mm lens would have a narrower field of view, i.e., it would be a bit longer or more telephoto... since the smaller sensor is only capturing the center portion of the entire area the lens sees.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Andrew McKee
Re: Cinema vs Photo
on Jul 29, 2010 at 9:00:10 pm

I was under the impression that the 7d/550D/T2i had APS-C size sensors like Red and 35mm and the 5D had a full frame sensor, larger than 35mm film.

Andy


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