Re: filmscanners: OT: Film grain

["Dave King" <kingphoto@mindspring.com>]

C-41 film has so much latitude that manufactures can rate it one to
two stops faster than the optimal speed and get away with it.  But at
the optimal speed, all photographic qualities (grain size, resolution,
and color accuracy) is best.  More exposure than "best exposure" is
less detrimental than less in terms of absolute quality, but within a
range of several stops, quality is for practical purposes, the same.
In other words, it's not really "overexposing" the film to rate it one
to two stops slower than the manufacture's recommendation.  Other
things being equal, faster ratings market better, so manufactures tend
to rate C-41 films at the minimum for acceptable good result.

LED scanners are different than enlargers however, and overexposure
more than two stops may build enough density to cause problems.  A
good general rating for most C-41 films is one stop overexposure (for
best quality).

Dave

----- Original Message -----
From: Rob Geraghty <harper@wordweb.com>
To: <filmscanners@halftone.co.uk>
Sent: Saturday, June 30, 2001 9:25 PM
Subject: filmscanners: OT: Film grain


> I was wondering if anyone on the list could explain to me chemically
how it
> is that overexposing a colour negative makes the film grain smaller?
I had
> no problem with a silver based film getting coarser grain wit
exposure, but
> C41 doing the opposite has me stumped.  I know it *does*, but I
don't
> understand how!
>
> Please email me off the list.
>
> Rob