Hi, I’ve had this issue with my enlarger and cannot find anything online that helps me with my issue. I have a Durst F60 enlarger, and I cannot make large prints because it does not distribute light evenly onto the photo paper. The center of the light is brighter than the edges. I tried buying a lightbulb specifically for enlargers and that didn’t work. Surely there’s something that should be a quick fix that I can do.
I'm sorry to hear about your issues with the F60. It might help to know what film format you're trying to enlarge, which condensor is installed in the enlarger and what kind of lens you have mounted on the enlarger. Keep in mind that if you are enlarging medium format negatives, you need to install the appropriate condensor and a suitable enlarging lens (typically an 80mm lens). Conversely, you may (or may not...) run into uneven illumination issues if you have the medium format condensor installed, but are using a 50mm lens to enlarge 35mm negatives.
Reviewing the manual, you will see that the F60 uses a light mounting system which allows you to center the correct bulb to obtain even lighting. Even lighting also requires that you use the correct condenser and negative carrier, depending on whether you are printing 6x6cm or 35mm. I've owned several Durst enlargers over the years, if not the F60. I find that when properly set up, they do not have problems with uneven lighting.