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.

 

[Dan Rainer]

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.

My bulb recently died and I replaced it right before the print sessions with the focus issues. I'm guess the new bulb kicks out more heat than the dying one. Just ordered a Beseler heat absorbing glass accessory. Thanks!

 

[logan2z]

My bulb recently died and I replaced it right before the print sessions with the focus issues. I'm guess the new bulb kicks out more heat than the dying one. Just ordered a Beseler heat absorbing glass accessory. Thanks!

I had negative popping issues with my 23C II even when using the heat absorbing glass. The solution, as @Pieter12 mentioned, was to use a glass negative carrier.

 

[fiddle]

I had negative popping issues with my 23C II even when using the heat absorbing glass. The solution, as @Pieter12 mentioned, was to use a glass negative carrier.

This.
The heat absorbing glass did help a little, but was still an issue until I got a glass carrier.
I ended up getting a regular 6x7 carrier, and buying the original replacement glass from khbphotografix in canada. Was able to mount finagle some mounting scheme. Was cheaper than finding a glass carrier.

 

[logan2z]

Was cheaper than finding a glass carrier.

The Beseler 6x9 glass carriers are very expensive - $245 at Freestyle. I have one and the hinges are cheaply made and require some fiddling to get them to close once open. I was disappointed in the quality given the asking price.

 

[MattKing]

This enlarger is a bit different than the 23 series enlargers.
Yes, negative popping is a possibility, but I don't recall it ever being much of an issue in the years that I used my Beseler 67 with a condenser head.
And yes, I know that the 6x7 head for the Printmaker 35 chassis is similar to the Beseler 67 head, but not identical.
I would still recommend looking in particular at the focus adjust mechanism.

 

[Pieter12]

I would still recommend looking in particular at the focus adjust mechanism.

I would think a simple test would be to shut off the enlarger for a bit to cool down and turn it back on and see if the focus is in the original state. That would point directly to the negative popping.