[LargeFormat] Processing 4X5 recommandations.

[Paul and Paula Butzi]

> About the Jobo drum processing, I have a few questions to ask....maybe some
> of you may help me.
> 
> What is the difference between magnet and cog drums?

Magnet drums have a magnet in the base; this magnet forms half of a
magnetic pair that attaches the drum to the drive in the processor.

Cog drums have a geared cog attached to the mouth end of the drum;
the cog attaches to an accessory on the Jobo processor called a 'Lift';
the rotation of the drum is driven by a gear on the lift.

If you get a Jobo processor, you definitely want a life, and you can't
use the magnet drive.  However, all Jobo drums can be fitted with cogs,
and the cogs are pretty cheap (a few bucks).

> 
> Since you put less fluid in the tank do you have to rotate them constantly?

The drums always rotate continuously on a Jobo.  About every two rotations the
direction of rotation flips.

> 
> At what speed do the drum usually roll in the processor. 1 rpm???

The drums rotate at about 40rpm.  On the Cpp-2 I use, it's continously
variable from about 25rpm to perhaps 80rpm or so.  Changing the speed
doesn't really seem to make much different when running film, although I've
heard it can make a difference when running Ilfochrome.

> And do
> they roll constantly?

Yes.

> 
> Are the film spool sold separately?? Or are they include with the drum?

Film reels are sold separately, yes.


-Paul
web site at www.butzi.net