Processing times in rotary tube processors

Are processing times for the various rotary tube processors
transferable from one brand to another? In particular, would Jobo times
be transferable to a phototherm processor? (Note: I don't think that
phototherm includes a presoak and the temperature is 75F, so let us
compare to other processures using a no presoak and 75F program).

Thanks.

Alan

wrote

Are processing times for the various rotary tube processors
transferable from one brand to another?

It depends on the process - rc, fb, bw, ra4, e5, c42 - and
how precise you need to be with the results.

I take it you are talking about bw negatives.

In my experience times are reasonably consistent between
a Jobo and a Unicolor drum. Small tank times translate if
you knock about 25% off the time - varies with the type of
film, of course.

The approach I would take would be to start with the Jobo
times and correct for temperature using the information
supplied by the developer and/or film vendor(s).

Example:
Kodak specifies:
Small tank: 9 min @68; 7 min @75
Jobo specifies:
6.5 min @68

~Phototherm time:
6.5min * (7min / 9min) = 5min @75

Try it and see if you like it. Modify and try again if
you don't. You are the only one who can judge if the
results are OK.

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation: F-Stop Timers, Enlarging Meters
http://www.nolindan.com/da/index.htm
n o lindan at ix dot netcom dot com