Re: [Leica] Film//Developer Tests

[Erwin Puts <imxputs@knoware.nl>]

>Has Erwin ever compared film/developer combinations, Pyro, Windisch, fx1,
>TechPan and Technidol, etc. to evaluate best combination(s) of "sharpness"
>and/or range to make maximum use of Leica glass?  In reading the Formulary
>catalog I see claims of developers capable of recording a 15 stop range
>with fine grain and high "acutance".

Of course I did. Would you like to expose film with such a marvelous
instrument as an M Leica without making sure the potential capabilities of
the optics/mechanics are not being degraded by emulsion/chemical
mishandling.
But here as elsewhere, we must part from history. Old wondermixtures and
secret formula have no place in the actual world of emulsion science.
Windisch, Pyro etc tried to get high acutance effects with films not made
for this exercise. In general now the high acutance era is gone. Not that
acutance is no longer important. No, most films and developers will produce
slight acutance effects. Many developer formula will have less impact on
the endresults nowadays, because films are more robust and will not react
very sensitively to different developers. Ilford for instance states that
their excellent Delta line is totally unsensitive to developer
characteristics as the chararteristics of the film are as it were inbuilt.
I used many developers from Rodinal, through D76 to XTOL on all modern B&W
films (From Agfa APX 25 to Fuji Neopan 1600). The differences are very
visible no doubt about it. But again, you need at least a 12 to 15 times
enlargement to see it.
My conclusions?
Techpan and Technidol/Rodinal or whatever is a combination with a stunning
resolution and richness of details. It is no acutance champion.
Rodinal is not my favorite: its gives tight grain, but very stong clumps of
it. It enhances the sharpness impression but ruins the fine gradations of
small details.
My preferred combinations: Agfa APX 25 and Paterson FX39 or XTOL. Ilford
PanF lLus and 100Delta in the same developers.
These developers have a very good balance between acutance and gradation
and willbringout the bst from leica lenses. The APX 25 and the PAnFPlus are
in the same league as Techpan but bring sharper results and finer tonality.
It is impossible to get a 15 stop range with any film/developer
combination. To accomodate this range you need a Contrast Index so low that
any sharpness/acutance or contrast is developed out of the film.
Here as everywhere there is a balance: a steep curve gives gradation , but
a smaller range of stops. A good acutance needs some grain forming activity
and that ia against the quest for very fine grain.
One must remember that a 35mm negative is a different breed from a 120 or
large format negative and many of the Zone System ideas will not work on a
35mm unless you adapt to the characteristics of the small emulsion area.
To sum up: try APX25 and XTOLand the best of Leica lenses is at your feet.
After this: use this combination until you are sure you know everything
about it.
Erwin