Bob and Cantore,
If the last photo of the OP's posted is the negative printed full-frame, then, obviously, I must be wrong. There is only slight falloff in the corners, which indicates that the lens is covering for the most part. (Although, I do see a slight clipping of the corners, it is not nearly as pronounced as in the first two images).
So, the fact that there was falloff at one point and much less now confuses me a bit. I can understand it if there were an illumination issue, i.e., condenser misalignment, something in the light path, etc. that caused the edge of the negative to be improperly illuminated, which was then corrected when the OP removed and replaced the condensers (or made some other adjustment).
I still fail to see, however, how you can get anything but a clean straight edge projected from the edges of the negative carrier unless there is a problem either with the lens coverage or the illumination. When things are set up correctly, there should be no such falloff as shown in the OP's original postings.
A thought experiment: I set up my enlarger to project a full-frame image slightly smaller than my 16x20 inch easel, so I can see the film rebate and the edges of the negative carrier projected on the enlarging surface. I then remove my 16x20 easel and get out my 8x10 easel. This I place on the baseboard so that one of the corners is centered on the enlarging surface. I am effectively cropping by moving the easel, and I am intentionally placing part of the photo paper "in the dark," i.e., outside the projected image. I make a print. I repeat this for the other three corners. As far as I can see, I should get no falloff at the corners other that that inherent in the optical system (i.e., the combination of falloff from the lens and slightly uneven enlarger illumination, which in my experience is 5-10% or so). I should have prints of the corners of my negative with the film rebate showing and nice clean lines from the edges of the negative carrier.
And Bob, don't misunderstand me, I really think your practice for cropping is best practice (I also center the area of the negative I am printing when cropping). And I understand your workflow completely. I just don't see how I can explain the OP's original problem by "cropping by moving the easel." I originally thought there was a coverage problem, now I'm leaning to misalignment of the light source somehow. Unless I'm really missing something here, if everything is aligned correctly, even with the slight falloff and the reduced lens performance at the corners of the image, there should be no problem getting a good image of edges and corners of prints. How could one print full-frame without the same problems?
Last edited by Doremus Scudder; 02-03-2012 at 04:50 AM. Click to view previous post history.