[Leica] TechPan mastered! (?) (Heavy reading)

[Christer Almqvist <christer@almqvist.net>]

I got a couple of Tech Pans at a flea market last weekend and I tested them
in Rodinal 1+150 and in Maco LP Docufine LC (stands for low contrast). I
guess the Docufine is only sold in Europe, but I think  it is a sort of
modified POTA (Darkroom Cookbook page 97) as it contains hydroquinone and
sodium sulphite. I had tried other developers earlier, but I was never
quite satisfied

I used an e.i. of 64 becasue lower film speed is not practical for me. I
photographed a grey card,  but I exposed 12 zones, as this makes it
possible to see what the result would have been if the e.i. had been one
half or a quarter of the the one to which I had set the meter. I also took
some portrait photos of my daughter, using a 500 watt halogen lamp sold a
DIY shop. That gave a very harsh light which I wanted in order to see how
the tonal range would turn out in extreme circumstances.

The Darkroom Cookbook gives a development time of 7 min for  Rodinal 1+150
and I developed for both 6 and 9 minutes. I used 4 ml Rodinal in 600 ml
water to develop one -half- film, in order to avoid capacity problem.
(Temperature was 68°F and agitation was 30 sec initially and 10 secs every
minute thereafter for all tests.) The results with Rodinal 1+150 were
dismal in both cases. The negatives were unusable.

The Docufine leaflet said develop for 13 mins for a beta of .80 so I
developed one half of the roll for 11 mins and the other for 15 mins. In
both cases the negatives looked good, but I have learned not to make a
final judgement until I have seen the enlargements. Another argument for
this, in this case, is that the Cookbook says that the Zone System approach
should not be used for determining film speed for document film as the
first printable density for these films can be as low as .03 above fb+f,
while it is .1 for normal films.

I measured the densities for all the zones for both film strips and then
played about a bit with the Apple and  a spread sheet. I made a table with
all the normal zones (I through IX) and typed in  the standard density for
each zone with  values I got out of a Zone System manual. Then I typed in
the densities that I had measure for each zone for the 11 min development
and also for the 15 minute development. The next step was to calculate the
average of these values which I assume would approximate a 13 minute
development. I then had the spread sheet calculate the density diffeernce
between the standard values and the values I had measured. I then divided
the density value differences by .17, which my  Zone System manual says
equals one stop. The table then showed over/underexposures relative to the
standard. The (calulated) values for 13 mins development showed diminishing
underexposure between .8 stop  (Zone II) and .1 stop (Zone V)  and  also
incressing overexposure from .8 stops (Zone VI) to 1.9 stops (Zone 9). A
somewhat steep curve in other words. Compared to similar tables for normal
films developed in Xtol, the Tech Pan negative should print on a one grade
softer paper.

In practice I could print the negative on Grade 2 paper, which is what I
normaly use with normal films. Incredible sharpness, and no grain, also in
comparison with APX 25 in Rodinal, and   that combo usually gives a speed
of only 16 or 25.  APX in Xtol gives more speed but less sharpness than
Rodinal.

Of course the Tech Pan/Maco print has a different flavor from Delta
100/Xtol or HP5plus/Rodinal print, but now we are into taste and maybe we
should leave that out of the discusssion. Or perhaps not. I have also got
usable prints from Tech Pan developed in Xtol and Tetenal Neofin Doku, but
I never fell in love with the look of these enlargements. With Maco
Docufine it is different.

YMMV, but this combo is worth a try.