Beseler Enlarger Focus Drift

[Dan Rainer]

I'm using a Beseler 67 print head on a Beseler Printmaker 35 chassis (picture below). I've had this setup for a few years with no issues. The last couple days I've noticed an issue while printing. I'd focus, stop down, and print as normal but after a print or two my focus would be wildly off. I took to focusing before everything single exposure, but still ended up with at least one print that was slightly soft.

I'm performing a realignment now, but I really don't think that's the issue. When properly focused, the prints are sharp corner to corner. However, as an experiment, I focused the enlarger and waited for 5 minutes—leaving my grain focuser in the same spot. When I rechecked focus, it was completely off.

Anyone have experience with something like this? Is it possible that the weight of the lens stage is causing the focus to sag over time?

 

[Pieter12]

The negative is popping from the enlarger lamp heat. Try getting a heat-absorbing glass or a use a glass carrier that holds the negative flat.

 

[mshchem]

The negative is popping from the enlarger lamp heat. Try getting a heat-absorbing glass or a use a glass carrier that holds the negative flat.

Absolutely, this is my first suggestion too.

 

[MattKing]

I would check the head elevation lock and the focus adjustment. I expect one or both are losing a bit of their locking strength, and may need parts adjusted or perhaps replaced.