Vignetting on LPL D6700

[rjhelms]

Hi all,

Was working in the darkroom today and had a problem with very heavy vignetting on an LPL D6700. I haven't used this particular enlarger in quite some time, so I can't recall if it's a problem I had with it in the past.

I was just making some contact sheets, and everything looked fine when I was doing test strips but when it came time to expose the whole sheet there was very obvious light fall off around the edges of the paper. The pattern of the light fall-off also didn't seem to be centered in the middle of the exposure.

I was using a 50mm lens at f/8, and had an empty 35mm carrier in the enlarger so I would expect fairly even light coverage. Since this enlarger doesn't have interchangeable mixing boxes for different film formats, and doesn't seem to have much by way of adjustments I can make in the light path, I'm at a bit of a loss.

Has anybody had an issue like this with this enlarger? Any ideas for what I could do to attempt to fix (or get around) the issue?

I do have other enlargers that I can use, so it's not the end of the world if this one is a loss, but it is a very nice machine and I'd like to have it in good working order if possible.

 

[ic-racer]

A light bulb, some distance from the contact frame, will give more even exposure than an enlarger. Even one that is properly setup.

 

[bdial]

Is the edge of the carrier in focus? Were you doing small prints prior to the contact sheets?

 

[rjhelms]

A light bulb, some distance from the contact frame, will give more even exposure than an enlarger. Even one that is properly setup.

That's a really good suggestion, thanks. However, I'm fairly sure there's something enlarger-specific going on, as I've been able to get satisfactorily even exposures doing contact sheets under an enlarger many times in the past but this one was way off.

Is the edge of the carrier in focus? Were you doing small prints prior to the contact sheets?

Yes, edge of the carrier was in focus. The contact sheets were the first thing I was doing in the darkroom yesterday, so everything should have been properly set up for them.

It's always possible I made a silly mistake with the set up, but my intuition tells me there's something up with the enlarger. I am going to try again tomorrow and see if I have any more luck.

 

[jimjm]

Does your LPL have the removable recessed lens board? On mine, I can mount the lens on either side of the board, bringing it further or closer to the negative. If it's not mounted optimally (my 50mm is mounted in the recessed position) it may account for the vignetting you're seeing. Also, I'd check to see that the aperture blades are closing down properly.

 

[rjhelms]

Does your LPL have the removable recessed lens board? On mine, I can mount the lens on either side of the board, bringing it further or closer to the negative. If it's not mounted optimally (my 50mm is mounted in the recessed position) it may account for the vignetting you're seeing. Also, I'd check to see that the aperture blades are closing down properly.

I don't believe that this enlarger has such an adjustable lens board, but I'll check - if that's the case, you're right, it would explain what I'm experiencing.

I didn't notice any issues with the aperture blades, but I will take a closer look when I'm next in the darkroom. I do have other lenses, so if that's the problem it should be an easy fix.

Thanks for the suggestions!