RE: old UV tubes less contrast?

Tsuyoshi,

Briefly you can you use any tungsten light source in a darkened room. I used
my Saunders 4x5 enlarger with the head raised to it's max height. Using an
enlarger will also allow you to control the light intensity with the
enlarging lens aperture. Null the analyzer on the neutral channel - white
knob. Instead of zeroing the needle on the center zero mark on the meter
face you should adjust the N channel potentiometer so that the needle is
deflected all the way to the left at the 100 units mark. With the analyzer
nulled this way you can read negatives up to a log 2.0 density. However, it
may be desirable or necessary to extend the max log value that can be
measured.

To do this I used precise ND filters placed over the aperture when nulling
the analyzer. For example, if you lay a 1 stop (0.30) ND filter over the
aperture and null the analyzer you will extend the maximum density capable
of being read to 2.3. After zeroing the meter with the ND filter and then
remove the filter from the probe it will deflect leftward past the 100 mark.

You can extend this father with the use of a denser filter or two or more
stacked together.

The downside to this trick is that the meter starts loosing it's linearity
when reading denser negs. You can check this by measuring a calibrated step
tablet. I prefer to use the Stouffers 4x5 calibrated tablet as it is easier
to position the steps over the aperture. Of course the ND filter isn't used
when reading a negative.

Once your interneg density is in the ballpark you can then make small trial
prints and evaluate the results. When making test prints be sure to print a
small step tablet along side of the image being tested. This will give you a
reality check on the process being used and also provide you with print
tones that can be mapped back to a specific negative density. You can also
use this method to interpolate negative densities made with pyro staining
developers which can't be accurately measured with a non UV sensitive
instrument like the PM2L. If your process allows the flexibility of
adjusting the print contrast, it maybe easier to work with a enlarged
negative that is a little less contrasty than your optimum value.

IMO, one of the best writes ups for producing enlarged negatives for
platinum/palladium printing (which can be applied to other alt. processes)
is Carl Weese's chapter on enlarged negatives found in 'The New Platinum
Print'. But there other sources too.

I don't claim that this method is perfect but it's cheap. And oh yes I do
have a manual. E-mail me off list and we can negotiate a price! ;-)

Don Bryant
  
Received on Sat Mar 4 15:28:57 2006