problem with a lens

[pat naughton]

Hi all, i have just joined up with this forum. I am from the Republic of Ireland and my name is Patrick. I was wondering if anybody might be able to help me with a little technical problem. I am using a Durst L1200 multigraph b&w enlarger. The lense is a nikon nikkor 80mm screwed into a 39 lens board. The problem i have is when trying to print from my 6x6 negs an area of shading appears on each of the four corners. I have tried adjusting the focal lenght etc...but to no avail. If anybody could help..it would be great.
Cheers.

[Nick_3536]

I don't know the 1200 but the lens easily handles 6x6.

[Robert A. Zeichner]

I would have to concur that the 80mm El-Nikkor should cover 6x6cm easily. I'm not familiar with the L1200, but it is possible that if your light source is adjustable for different formats, that it is simply set incorrectly. If your enlarger has a condenser head, this is possibly the problem. One other possibilty (and again, not being familiar with the L1200, I can't be sure) is that some lens boards on Dursts have cylinders that hold the lens further away from the negative than other flat boards. It might be that if you are using such a board, that the vignetting is happening there. These are just some guesses, but hopefully might give you some ideas that will help. Good luck and please let us know how you solve this.

[pat naughton]

Cheers for that advice. i shall investigate further with these tips in mind.

[al olson]

This sounds similar to a problem I had when I added an 80mm lens to my condenser enlarger and did not reposition the condenser. The positioning of the condenser affects the light distribution. If you have it in the 50mm position and are using an 80mm lens you will get vignetting and darkening along the edges and in the corners.

Some enlargers are designed to allow repositioning of the condenser and some require a different condenser lens. I think Robert is on the right track.

[Joseph O'Neil]

I agree with the above about repositioning the light source. I've seen "dark corners' on my own enalrger before.
I'm not that familiar with the Durst, but on my old Omega, I had lensboards for almost every format (even 110 - go figure:) ), but to use each format, I had to move the condenser lenses - and, in the case of 4x5, go from the lens board to the drop down lens cone. I would imagine the same is true for the Durst & many others.

joe