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Film Grain discrepancy


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#1 Bill Munns

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Posted 08 March 2010 - 10:40 PM

I'm studying two different film frames I've scanned, both by the same scanning system at 4K.

I couldn't upload the image to this forum even though the image was only 93K, and twice got a message of "Upload unsuccessful" so I had to upload it to another forum and it can be seen at this direct URL:

http://www.bigfootfo...showtopic=29020

The left image is camera original and known to be Kodachrome film from 1968 and it has an excellent fine grain and detail.

The right image may be a copy, original stock unknown, but it's graininess is so extreme as compared to the right that I can't figure out why.


Options I can think of are:

1. Using a high speed Ektachrome, like the 160 ASA maybe?

2. Asking the processing lab to push one or two stops in the development?

3. Copying grain buildup?

4. Original shot on 8 or Super 8mm and blown up to 16mm?

5. ???

I'm open to any idea of why the one is so grainy as compared to the other, when both were scanned by the same device and at the same scanning resolution, and are both shown at equal image size in Photoshop when the composite image was made for display.

Thanks for any ideas.

Bill
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#2 Paul Bruening

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Posted 08 March 2010 - 11:25 PM

The right side's cooler than the left. Kodachrome, Ektachrome difference came to my mind first. It looks like any of your suggestions could be in play, though.
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#3 Bill Munns

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Posted 09 March 2010 - 12:33 AM

In the same URL referenced in the top posting, I have added another comparison if you go down about 4 replies from the top.

It shows trees in each film, and in the grainy one, even the sky is riddled with grain while in the sharp image, the man's yellow shirt is a smoth yellow. So the grainy film on right can't even old a solid color like the sky, withough an astonishing amount of grain.

Sorry I can't post it here. The image posting process doesn't seem to work for me in this forum.

Bill
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#4 Dominic Case

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Posted 09 March 2010 - 04:22 AM

So, you are asking why product X (unspecified stock type, gauge, speed rating or any other property) is grainier than something known to be Kodachrome.

Turn the question around and it sounds like an advertising campaign of the worst sort. "Kodakchome has less grain!". -Than what? Cornflakes?

But really, any answer could only be speculative, and you've hit on most of the possibilities already. I think Kodachrome was around 25ASA then, and acknowledged as remarkably fine-grained. Anything else used (for greater speed, availability, processing convenience) would be grainier. Apparently the two images were part of different films shot by different people: they obviously made different choices about the acceptability of gain versus other parameters.

It would help if the film stock could be identified by looking at the entire film area, not just the image. That could tell "a film person" a lot about the stock type, whether it's duplicated, enlarged, printed from a negative, etc etc.

BTW, I would pick up on your comment that "the grainy film on right can't even (h)old a solid color like the sky". Grain is an inherent part of the structure of an image in a film emulsion. There is no reason why a "solid" colour would be less grainy than any other area. It's not the same as (for example) compression artefacts in a digital image. And in fact I don't think the blue sky is any grainier than the rest of the image in the same frame, though undeniably much grainier than the Kodachrome image.
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#5 Charles MacDonald

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Posted 09 March 2010 - 11:30 PM

BTW, I would pick up on your comment that "the grainy film on right can't even (h)old a solid color like the sky". Grain is an inherent part of the structure of an image in a film emulsion. There is no reason why a "solid" colour would be less grainy than any other area.

In fact a solid colour area is likely to draw attention to the grain, while a "busy" area will have the eye looking more at the image and less at the grain.

I would agree that looking at the entire frame and the edge printing on the film may give some idea as to what you are looking at. Kodachrome movie film was always low speed, while Ekatachrome was often used in it's higher speed versions. That is not to say that one of the "other" stocks that have been available were not used, I think ANSCO made an Anscochrome 500 for a while in the 1950 era for example.
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