New bulb for focomat 1c

[Hans Berkhout]

The Focotars are process lenses..and can be used wide open or 1/2 stop down for max sharpness..this comes from Ralph Gibson.
Dont know why you would want to degrade the image at f11..
You could also plop a small color head on it and have longer exposure times.

Re Focotars: True but you better make sure the negative (and lens) plane is absolutely parallel to the printing paper surface.

 

[PKR]

It depends on the speed of the paper you're using and the length of exposure you like to use. For example some Foma papers are extremely slow and Berger is much faster as is Ilford multigrade warmtone. Hard to answer without answering these questions.

I personally like around a 30 second exposure so whatever it takes to get that with the lens at f8 for a specific paper and magnification.

I tried a half dozen bulbs and couldn't find one that gave even illumination. No matter where I put the height illumination was different at various places. I measured it with a Minolta incident meter.

I use multigrade paper and putting filters under the lens was always a pain. I wound up adapting an Omega 2-1/4 dichroic head to it and now the illumination is perfect across the field at f8 and all I have to do is dial in my contrast filters now.

We rigged similar with an 8X10 Durst in a friends lab. Durst Dichroic head plus condensers. I've worked on two of these Durst enlargers. They're the size of a Bridgeport Mill and weigh as much.

Omega heads should be easy to find. The small heads aren't generally used commercially so, the filters should be in good shape. Those filters fade with a lot of use.