Re: Lith film

I'm confused by all this talk going on here. Can you please correct the
below entries? (helping me to comprehend contrast control in enlarged
negatives by reversal process)

1. Let's assume you have a 35mm negative with a density range of 1.6
(density range is defined as = Dmax - B+F),

2. You make a pozitive test and determine (say...) 3 secs as your pozitive
base exposure (pozitive base exposure is defined as = *** the least amount
of exposure letting
you see enough highlight detail in the pozitive test *** )

3. If you need an enlarged negative with a 1.6 density range (Dmax
irrelevant), then you will expose 3 secs, then flash the correct amount
(found by testing) for the desired Dmax. Dmax may be 3, 2 or another value
depending your flash exposure, the density range will not change, what will
change is the Dmax and base + fog density (If Dmax = 3 then B+F = 3 - 1.6 =
1.4, if Dmax = 2 then B+F = 2 - 1.6 = 0.4)

*** 4. If you need an enlarged negative with more than 1.6 density range
then
you should expose it more than your standard pozitive base exposure. For
instance, 3 secs. x 4 = 12 secs (you need to test to find the correct base
exposure multiplier) and then you will flash the correct amount for the
desired Dmax (flash timing will only change when your enlarger head's height
and/or bulb will change) ***

To determine the flash exposure time for the desired print size (head
height) and Dmax:

a) Make flash test stripes and develop, stop, open lights,bleach, clean and
redevelop as usual. Then,

b) Read the test stripes with a densitometer and see if there's a density
close to what you need. Adjust the exosure time and go to (a) to see the
result. Repeat this until you're done...

Did I get it rigt? If yes, then this mean Philippe did the very important
operations markef with *** but didn't manage to get a decent negative...
Philippe, is it so?

Regards,
Loris.

----- Original Message -----
From: "Dave S" <fotodave@dsoemarko.us>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Friday, December 12, 2003 10:51 PM
Subject: Re: Lith film

> Sandy,
>
> The density range of your enlarged negative is (should be) the exposure
> range of your final material, but Philllip is talking about his original
> negative having a density range of 1.6 (about 11 steps on a step tablet).
> This means that the exposure range of the lith film must be that or
greater
> than that, otherwise we will have compressed tones.
>
> Dave S
>
> ----- Original Message -----
> From: "Sandy King" <sanking@clemson.edu>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Friday, December 12, 2003 3:33 PM
> Subject: RE: Lith film
>
>
> > Phillip Monnoyer wrote:
> >
> >
> > >
> > >What I encountered is indeed a problem of exposure range rather than
> > >a problem of density range (as Dave points it).
> >
> >
> > I really don't understand what Dave meant by his explanation. In my
> > work with lith film the density range *was* the exposure range. I
> > don't see how it could be otherwise, assuming you don't have some
> > kind of very strange curve.
> >
Received on Wed Dec 24 10:18:52 2003