Jerry Orabona (jorabona@jerryo.com)
Thu, 20 May 1999 19:41:14 -0400
> It may not be film speed at all that influences the final
> negative density.
> Many studio photographers using medium format equipment, without TTL
> metering, have adapted and reduced their E.I. rating empirically to allow
> for bellows/focus extension. This is explained in Gene Nocon's bbok on
> Black and White printing.
>
> Cheers......Tony McLean.
Dear Tony--
I'm sorry to say that Gene Nocon couldn't be more wrong.
1. Bellows factor does not change with light sources, only magnification.
2. People take close-up photos outdoors.
3. Unless you are working at extremely close distances or are using a view
camera the bellows factor is negligible.
If there is a difference in E.I. between tungsten and daylight sources, I
shoot both and have never noticed, it must have to do with the film's
greater sensitivity to the blue/green wavelengths.
The only way to be sure is to run a film speed test measured on a
densitometer. I have a student who owes me an extra credit assignment. I
think I just figured out what her project is. I'll let you know what the
results are.
Jerry
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