I've just returned from vacation, and have finished 10 days of digests, so I
hesitate to start a lengthy discussion. My head feels like one in a horror
movie, where a side opens up, and thousands of OM digests explode out. Oh
well, here goes...
> First, concerning slide profiles: as all slides are meant to be projected
without any color correction, there shouldn't be >any need for different
profiles, should there?
Are they? I will try to remember to ask my drum scanner owning friend about
this, but I know he has different LUT's (look-up tables) for different
films, both neg and chrome.
>(Print film is different, and the manufacturers tell you what filtration to
use in
> your enlarger and how the paper will respond - equivalent to color profile
for a scanner).
Only loosely. Any recommendation is only a starting place for a specific
film type, and is influenced by emulsion batch, both film and paper,
enlarger (especially bulb and filter condition), and chemistry (this is why
commercial labs use replenished chemistry and run frequent test strips, and
why home color printing can be mind numbingly difficult).
>In practice of course there is a small variation (even batch-to-batch)
which is why people think one type of slide film is >too green / too red /
<insert your
> opinion> but do the manufacturers agree?
Not even batch-to-batch, ALWAYS. This is why some professional chromes,
especially sheet film come with an instruction sheet that includes actual
ASA with color filtration recommendations.
>If so, I suppose they think it's a good thing - and would likewise think
that scanned prints should also have the same color >cast...
All negative films had different filter packs/LUT's. That's the main thrust
of the manufacturer's efforts along the line of Kodak's Portra line. The
primary goal of that R&D was to get a line of different speed films with
similar characteristics that will all print with the same filter pack. Note
that the money was spent not to directly aid the photographer, but the lab.
Of course, ultimately, the photographer benefits, but remember, virtually
all portrait/wedding photographers buy the cheaper print, many are machine
printed.
Of course, there are other ways that films are easy/hard to scan besides
color balance.
Go for it, I'm taking a rest!
Bill Pearce
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