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#1 Jim Nelson

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Posted 15 August 2010 - 06:55 PM

How many perfs does 35mm film have? And how many does super 35mm have?



Thanks for your help :)
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#2 Tom Jensen

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Posted 15 August 2010 - 08:23 PM

How many perfs does 35mm film have? And how many does super 35mm have?



Thanks for your help :)

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#3 David Mullen ASC

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Posted 15 August 2010 - 08:58 PM

The original 35mm movie format was 4-perfs tall per frame. It's still that way for 35mm print projection. But now we have cameras that pull down less than 4-perfs for a shorter height, creating a less-tall, more widescreen shape. The original 4-perf 35mm silent era movie format had an aspect ratio of 1.33 : 1 (4x3) because the negative image area was about 24mm x 18mm (the film stock itself is 35mm wide because that includes the perfs, all the way to the physical edge of the film, but the picture area is inside that so is smaller).

Projection formats like 1.85 : 1 involve the use of a mask or matte in the projector to crop this 4x3 area down to 1.85 : 1, wasting about one perf of print area vertically.

So when you only pull down 3-perfs worth of negative, you get a shape that is close to 1.77 : 1 (16x9). This is more optimal (less waste) when shooting for modern widescreen shapes since movies are no longer 4x3, and TV is starting to go away from the 4x3 shape as well. But since all 35mm print projection is standardized for 4-perf, a 3-perf negative image area has to be converted / transferred onto 4-perf 35mm for making prints.

2-perf 35mm pulls down even less film, at half the height of 1.33 : 1 (4x3) 4-perf 35mm, the image becomes 2.66 : 1. This is close to the 35mm anamorphic projection format 2.39 : 1 (you just trim the 2.66 width to 2.39.) Often the 2-perf 35mm camera gates don't even expose the full 2.66 : 1 width, they only expose a 2.39 : 1 width.

"Super 35" means exposing the full width of the negative from perf row to perf row on each side (about 24mm wide), not leaving room on the left for an optical soundtrack (which normally reduces the usable picture area to about 22mm wide). It is also called "Full Aperture" photography. So technically Full Aperture 4-perf 35mm and 3-perf 35mm could be called "Super-35" but most people only call it Super-35 when you are shooting 4-perf 35mm exposing Full Aperture.

Ever since the sound era began, the print reserved the left side of the frame for an optical soundtrack, so cameras started not exposing a strip on the left side, which shifted over the optical center of the lens. This way, you could shoot a negative this way and make a contact print and just add the soundtrack stripe to that left side reserved for it. If you shoot Full Aperture, like they did in the Silent Era, you are using more negative because you are not leaving room for the soundtrack, but this means you can't make a direct contact print off of the negative and project it IF you want to put a soundtrack stripe on the print. So Super-35 movie have to be converted in post to make room for the soundtrack stripe on the print.
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