From: Robert W. Schramm (schrammrus@hotmail.com)
Date: 04/17/00-08:22:05 PM Z
I am glad someone agrees with me on this. I perhaps had my numbers off
but I was in the ball park. Color positives - 8:1 to 16:1
B & W. Negatives - 64:1 to 144:1.
I had saidthat this came from several textbooks and Sil asked me
what the references were. I did spend about a hour today looking
but never found them. When I quit teaching 2 years ago, I gave a lot
of books away to students. Anyway, without the references I am sure this is
correct. If you think about it, tonal range is related to latitude. It is a
well known fact that color positives have a
latitute of only about +- 1/2 a stop. By comparison, a B & W negative
film can have a latitude of +- 2 or 3 stops and thus a greater tonal range.
I would agree that if the color positive is all you have and you
are making enlarged negatives for some process that does not require
a negative of great range or don't really care, then, by all means
this would be a fairly easy way to make enlarged negatives. I was just
pointing out one disadvantage of doing this.
I have used all kinds of methods of making enlarged negatives. Most
of them worked fine for all processes but platinum. I just could
never get a negative that would equal the tonal range that is
possible with a platinum print. I finally bought an 8 x 10 camera
and started making in-camera negs for platinum. This resulted in
some of my most sucessful prints (as measured in terms of awards and
sales).
Bob Schramm
>From: James Romeo <jromeo@iopener.net>
>Reply-To: alt-photo-process-l@sask.usask.ca
>To: alt-photo-process-l@sask.usask.ca
>Subject: Re: Color transparency to B&W-On the other hand.
>Date: Sat, 15 Apr 2000 19:30:19 -0400
>
>Tom
>I am interested in how you use the FP4 for your enlarged neg.
>I have used tmax100 and it works but I am prefer Ilford.
>Eny info you have on using FP4 I would appreciate.
>I should look into that Berger film.
>James Romeo
>----- Original Message -----
>
>From: alt-photo-process-l@sask.usask.ca
>To: alt-photo-process-l@sask.usask.ca
>Subject: Color transparency to B&W-On the other hand.
>Date: Sat, 15 Apr 2000 15:23:06 -0700
>
>I have written about my use of color transparencies to FP4 for enlarged
>negs
>before on this board. I use this method quite regularly. It has both real
>advantages and disadvantages.
>
>First: to the original question, this is not how I would go about making
>conventional B&W prints. I only use this for alt process printing were a
>very large contact size neg is needed. 20x24 inch cameras are such a big
>pain ;-(
>
>B&W neg film is cheaper, more forgiving of exposure errors, and has far
>wider density range (can hold detail in very bright and dark things in the
>same scene) than color slides.
>
>A good (non super saturated) transparency film (E100N, Astia) can hold
>detail from zone 3 to zone 7 (two stops under meter to two stops above).
>That is 4 zones or a 16:1 ratio. Reducing the development of E-6 film
>results in little more than loss of film speed.
>
>A good B&W film can easily hold from zone 2 to zone 8 (three stops under
>meter to three stops over). That is 6 zones or a 64:1 ratio. You can use
>"zone system" type "minus developments" to get even larger ratios, such as
>Robert mentions below.
>
>So, what is the advantage to shooting the transparency and then enlarging
>onto panchromatic B&W film in the darkroom? It is perhaps the easiest of
>the optical/chemical methods for getting large contact print negatives for
>alt process work. That assumes that you can either control the lighting
>ratio (studio work) or simply prefer to shot normal to low contrast scenes.
>
>--
>Tom Ferguson
>http://www.ferguson-photo-design.com
>
> > From: Sil Horwitz <silh@earthlink.net>
> >
> > At 2000/04/15 04:22 PM -0400, Robert Schramm wrote:
> >> Several different photography texts I have checked say that color
> >> images have a tonal range of 8:1 to 16:1 at best, while black and
> >> white images have a tonal range of 144:1 to 256:1 at best.
> >
> > Doesn't sound right. The multiplicity of color layers should result in a
> > greater tonal range when extrapolated to BW. Can you give us the
>references
> > in "several different photography texts"? I'd like to check their
>testing
> > and evaluation process, as well as when the evaluations were done,
>because
> > early color films weren't much good at reproducing intermediate tones.
>When
> > I was teaching color theory, my conclusions were just the opposite!
> >
> >
> > Sil Horwitz, FPSA
>
>
>
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
This archive was generated by hypermail 2b29 : 06/13/00-03:09:48 PM Z CST