Single perf, double perf...what does it all mean?

[Filmosity]

Can anyone explain what single perf and double perf, or any other perf for that matter, means?

What's the difference between perforations, and what effect do the perfs have on filmmaking?

On a related subject, where can I see examples of the different aspect ratios and shooting formats (i.e., spuer-8, 16mm, super16, 35mm, super35, etc.)? I'm really looking for images of the acutal frame size on the film.

Chris

 

[David Mullen ASC]

It's perhaps time you started reading some cinematography textbooks because these are the sorts of questions that take a lot of time to answer.

The short answer is a "perf" is short for perforation, or sprocket hole. In 35mm, the sprockets always run on both sides of the film (double-perf), but in 16mm, you can get the film stock with sprockets only along one side (single-perf) because the Super-16 format exposes a wider frame than regular 16mm that extends out to the edge where the perfs would run on the opposite side. However, you can run single-perf stock in most regular 16mm cameras.

There are differences (slightly) in the shape of the rectangular hole cut for the perf for camera negative versus print stock. Print stock perfs have rounder corners to reduce the chance of tearing or breaking during projection, whereas camera stock has some sharper corners to allow better steadiness.

The ASC Manual gives the dimensions of each format, camera and projection.

I have two large wall posters from the BKSTS that show film formats on one and widescreen film formats on the other, using photos of film strips in actual size. Here's a sliver of one of them:

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You can also find info at the Kodak website, like here:
http://www.kodak.com/US/en/motion/support/faq/index.jhtml?id=0.1.4.11.16&lc=en

 

[Filmosity]

ugh, i feel like such a dope. Thanks for the info. I have so much going on right now, I got a bit confused. I don't have much film experience, but I'm in the process of reading several cinematography and directing books, so please bear with me.

Thanks for the info again.

-Chris

 

[locomonker]

David,
Would you recommend any textbooks in specific to learn about this type of thing?

Joel

 

[David Mullen ASC]

Things like 35mm formats, perfs, etc. are covered in most cinematography textbooks -- I co-wrote "Cinematography" with Kris Malkiewicz, which emphasizes 16mm shooting. But there is also Blain Brown's "Cinematography", Ascher's "Filmmakers Handbook", and a number of old textbooks that have that basic info.

Kodak's website as a lot of good info too:
http://motion.kodak.com/US/en/motion/index.htm

 

[locomonker]

I checked the Blain Brown book and it didn't have too much on the subject but the Kodak site was extremely helpful-- thanks a lot!