Re: CMOS or CCD on digital camera ?
From: William R Mattil (wrmattil_at_ix.netcom.com)
Date: 12/23/04
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Date: Thu, 23 Dec 2004 04:50:34 GMT
Michael Toms wrote:
> Can one do the same with a standard SLR B&W film by scanning three
> pictures taken in RGB? How do you combine them?
>
>
Yes. Its done all the time. Particularly so with fast system. Including
Schmidt Cameras. The trick is to use a film that has exceptional grain
and sensitivity at the "colors" that you are imaging. For most B&W films
the problem is the red. Few B&W films have decent red response and
reasonable reciprocity rate. The lone exception to this is Tech-Pan
which has truely exceptional grain and red sensitivity and the
reciprocity can be tamed by hypering the film and judicious use of
pre-flash. The resultant images can then be scanned and "registered"
using a software program such as Registar and then combined in Photoshop
or Picturewindow or MaximDL.
The trick with this is adjusting the exposures so that you get a natural
looking image. Most filters have varying transmissivity and the lengths
of exposures are not the same. CCD is less tender in this regard due to
the nature of the detector itself.
Of course all of this is a moot point since the only decent B&W Astro
film is being discontinued by Kodak.
Regards
Bill
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