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Film equivalency


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#1 Robert Sawin

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Posted 26 November 2008 - 11:38 AM

yesterday I was at fotokem and I was talking to one of the film lab techs there about pushing my film. I shot 16mm film using only one arri 2k light through the window. there where wooden blinds on the window to add some texture to the room. the issue was that the highlights where reading at f2.8 and my zoom lens had a max f stop of f3.3. even tho the film was under exposed at about a half a stop, the tech suggested I push the film to 1.5 stops. so I oked the go ahead to push it that much. But when I went to entertainment post to reserve for telecine an older man who had a lot of wisdom to share told me that by pushing the film 1.5 stops it increased the grain structure about three times. so essentially if that 16mm film stock was blown up to 35 mm the grain would be 1000 EI and by pushing it 1.5 stops thats like 2000 EI equivalent to 35mm film. I guess thats ok but I shot with a 1600 speed film before and that was kinda granny so I can only imagine.

so here is the question. why shoot 35mm 500 or above EI when I can shoot 16mm to match the equivalent grain structure. for example a 16mm film rated at 250 EI has the equivalent grain structure of 35mm film rated at 500 EI. Essentially the film speed of 16mm is double that of 35mm. Now is there any real disadvantages to shooting 16mm film and blowing it up to 35mm? especially with the new film from Kodak like the vision 3. I mean can a movie goer really tell the difference between 35mm scanned at 2k and a 16mm scanned at 2k?
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#2 Dan Goulder

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Posted 26 November 2008 - 01:35 PM

so here is the question. why shoot 35mm 500 or above EI when I can shoot 16mm to match the equivalent grain structure. for example a 16mm film rated at 250 EI has the equivalent grain structure of 35mm film rated at 500 EI. Essentially the film speed of 16mm is double that of 35mm. Now is there any real disadvantages to shooting 16mm film and blowing it up to 35mm? especially with the new film from Kodak like the vision 3. I mean can a movie goer really tell the difference between 35mm scanned at 2k and a 16mm scanned at 2k?

I would question the grain structure comparison between 250ASA 16mm and 500ASA 35mm. I'm not sure that comparison would hold once the 16mm is blown up to 35mm, which I assume is the comparison you're making. Regarding the difference between the two formats when both have gone through a D.I.: There will still be other differences in terms of resolution, sharpness, and color saturation which will favor 35mm. That said, there's no reason why one can't successfully shoot a feature in 16mm (preferablly super 16). It's been done numerous times.
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#3 David Mullen ASC

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Posted 26 November 2008 - 02:42 PM

500 ASA stock doesn't look twice as grainy as 250 ASA stock for one thing, so it's not as simple as that, plus 35mm is more like four-times larger than 16mm, not twice as large (depending on the aspect ratio), just like 4K is four times the data of 2K. You have doubled both the horizontal and vertical amount of information (again, I'm simplifying because aspect ratio comes into play.)

Besides grain, there is also the resolution difference.

However, Super-16 blow ups to 35mm can look fairly good and sometimes, it is hard to tell the difference compared to 35mm photography, except in wide shots where resolution becomes more of an important factor.
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#4 Brian Drysdale

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Posted 27 November 2008 - 04:32 PM

I wouldn't have pushed the film if I was only 1/2 stop under, it should print up pretty well and will look a lot better than being forced 1.5 stops during development.

I'd shoot with the slowest stock you can practically use.
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