Choice of Focal Length

[Joshua Provost]

A basic question to help my understanding of lens choice from someone who has never shot film...

 

I'm trying to understand the lens choices and field of view as I read an AC article. Someone may say they shot with a 50mm or 40mm lens, because it gives a certain field of view or perspective.

 

I guess my real question, is how are they composing their shots, with the full aperture gate in mind, or the projector gate? There is some cropping involved, so I'm wondering which a DP has in mind when choosing a lens.

 

Also, a follow-on, when a Hollywood film is released on DVD, is it similarly cropped to the projector gate, so it matches what audiences see on the big screen, or is it a larger portion of the negative?

[Michael Nash]

Movies are usually framed for a consistent aspect ratio, which is marked in the camera's viewfinder. Usually you shoot a framing chart at the beginning of production that serves as a common guide for all the release formats (film prints & video transfers).

 

These days with HD and 16:9 enhanced DVD's it a little easier to keep the same aspect ratio in all release formats. 1.85:1 is very close to 16:9, so those movies are either transferred with slightly more vertical space to fill up 16:9 or letterboxed slightly to keep the 1.85:1 frame. 2.35:1 movies are usually letterboxed on DVD's.

 

When standard 4:3 television was the only video format, 1.85:1 movies were often transferred with a little extra vertical space and the sides slightly cropped, sort of a compromise to keeping most of the film composition on screen. 2.35:1 movies were usually transferred "pan & scan."

 

It's not uncommon to have two aspect ratios marked in the viewfinder; one as the main release format and the other as "protection" for other release formats.

 

http://www.csc.ca/news/default.asp?aID=1087