I handle the exposure times by adding a 2 stop neutral density filter to
the enlarger lens. Cold lights can work, with some limitations. If your
original is in color (neg or transparency) it will "twists" the color/gray
balance a lot due to it's "blue" nature. I usually get my otherwise unused
condenser head out for this work.
Another problem with using "camera" film for enlarged negs is that we
usually use paper developers in order to get the needed contrast and strait
line curve. This leads to a very short development time, often leading to
mottled highlights. I develop my film for 5 minutes in normal FILM
developer, then transfer it to diluted paper developer for 45 seconds to 2
minutes (depending on the alt-process planned and original film's
contrast).
Best results with this system seem to be from color transparencies
(assuming your original scene's contrast is low enough for transparency
film). I assume this is true because only one enlargement/transfer is done
(pos to neg) as opposed to B&W or color neg work (neg to pos to neg).
tomf2468@pipeline.com
> >>I use Kodak TMax100 8"x10" sheet film to make my
> >>interpositives. It is relatively inexpensive and
> >>has the advantage of being panchromatic. So, I
> >>can make interpositives from color film without
> >>losing information in the red portion of the
> >>spectrum, as I would if I used one of the
> >>orthochromatic process films which many use for
> >>negative enlargement.
>
>> Do you make the interpositive using an 8x10 camera with this film or with
>>an enlarger? If you use an enlarger, how do you manage the exposure times?
<SNIP>
>I make interpositives with an enlarger. My use an old Omega D2 4"x5" with an
>Aristo coldlight head. In order to get reasonable (>5 second) exposure times
>with TMax, I use an Omega dimmer, which is a rheostat (or some similar
>device) that in the circuit between the 110v AC source and the light source,
>in series with the timer.<BIG SNIP>