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Re: [OM] The curses and joys...

Subject: Re: [OM] The curses and joys...
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Tue, 28 Apr 2009 09:14:23 -0500
>
> You mentioned that there is depth to film that you dont see in digi, arent
> you loosing that during the A/D conversion?
>


No. It has to do with the tonal bias the film assigns to the captured light.

For example, in a bright sunny day in wintertime, you'll see the snow in the
shadows turn blue in digital capture. Some films will react differently to
this specific shade of blue and either turn the shadows magenta, green, gray
or blue--all while leaving the sunlit portions neutral.

Another example, would be in a mixed flash and tungsten lighting. As you
have the WB set for flash (daylight or approximately 5300 Kelvin) the
tungsten lighting in the background will turn quite orange. However, with
some films, the tungsten lighting will warm, but won't turn nuclear.

What does that have to do with poor lighting?  Print films are more
forgiving than digital because the exposure response curve is not linear. As
you underexpose the film by one stop, it only decreases by .8 stop.  As you
underexpose the film by two stops, it only decreases 1.5 stops. As you
underexpose the film by three stops, it only decreases 2 stops. The farther
you get from the nominal exposure (mid-tone, properly exposed), the less
change it has.  Only in the middle exposures (+/- 1 stop from mid-tone) is
the response anywhere close to linear.  Velvia is an example of a film that
stretches the mid-tones and instead of compressing the low-values, it just
drops them off into blackness.

So, in my concert shoot, using identical exposures and ISOs, the digital
image has more blown highlights from the follow-spots and nearly no
background. The house lights were set extremely low (safety lighting, only).
The digital images have black backgrounds, the film images actually have
substantial color and background details. The highlights in the film images
are still blowing out, but the transision is smoother in an organic way
without the nasty color shifts and harshness.

Scanning the film makes no difference, because the film has captured the
extremely wide light-levels and compressed them into a range the scanner is
able to use. The mid-tones still have a proper contrast, but the highlights
and shadows are pulled in.

AG
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