Re: Konica base fog

[Russ Rosener <rrosener@xxxxxxxxxxxxxxxxxxxxx>]

I've noticed Konica 750 has a much higher base fog than TMAX 100 for example. The higher base fog
can actually help you in pulling a decent print out of an underexposed negative. It acts almost
like a contrast mask so less burning and dodging is required. I have no idea if this was
intentional by the film manufacturer or is just a by product of the IR dyes used.
By the way, can you still buy the Konica new? I have a ton of it frozen, but will need more
eventually.

Russ Rosener

HypoBob wrote:

> >
>
> Stan,
>
> Konica 750 does have higher base density than most 120 format films.  It always takes about one
> stop more exposure for the contacts.  I have shot refrigerated Konica 750 that is over two years
> out of date without any noticeable degradation.  (Of course in the world of IR since one never
> knows exactly what to expect, it is hard to be disappointed.)
>
> The orange filter does allow additional light through the lens, as compared to the 25A, but it
> is light that Konica 750 does not "see", so you get no benefit in terms of film speed or
> additional tones in the negative.  Konica 750 has a bi-modal sensitivity curve with one peak in
> the blue to blue-green region and the other in the red to near infrared.  The orange filter is
> passing some wave lengths between those two peaks where the film sensitivity is zilch.
>
> Bob
>
> ----------------------------
> Stan Patz wrote:
>
> >
> > To the group,
> >
> > I just ran some Konica 750 tests in a new 120 rollfilm camera. I processed
> > similar rolls of film in D-76 1:1 for 8min @ 68*F, and Rodinal 1:50 for
> > 7 min. Both rolls looked good - images came out with the same film speed! But
> > both rolls showed fairly high base fog; slightly grey. Is this usual, or a
> > problem with 1yr outdated, but refigerated film.
> >
> > For the tests, I used a 25a filter, and got good results. On a few frames, I
> > used a Tiffen "orange" filter, but got no speed increase over the 25a.
> >
> > What is the Wratten equivalent to the Tiffen filter, and has anyone found
> > and advantage to using it over the 25a?
> >
> > Stan Patz   NYC
> >
> > SKP113@xxxxxxxxxxx
> > www.PatzImaging.com
> >
>
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