Mysterious Concentric Rings on my Prints

[Keith Baker]

Greetings, I have a curiuos problem. My prints have visible concentric rings a s part of the image. I am printing 4x5 B&W negs with an Aristo cold light, Bess ler MX enlarger, Nikon 135 mm lens, Ilford filters (beneath the lens) and VC pap ers. The problem is more obvious in areas of sky where it's easy to see. The r ings are not centered on the paper, they do not coorespond to the windings of th e cold light tube, the diffuser material looks uniform, the negs are clean, the filters are apparently uniform and the lens appears clean. My nice prints are b eing haunted!!! I would like to find out what causes this and what to do about it. I would rather not reinvent the wheel on this one. Thanks in advance to those who contribute helpful info. Keith

[TAN K H]

Are you using a glass carrier? Sounds like Newton rings to me.

If so, you might want to get a sheet of anti-Newton glass installed as the top piece nearest the light source.

[Trevor Crone]

Does sound like Newton rings which are caused by moisture between the negative a nd glass plate of the negative holder and appears as an interference pattern on the image. I was plagued with this a while back and no matter what I did I could not get ri d of it until I used AN glasses top and bottom in my carrier. Now you have to be causious if you use two AN glasses, for some makes will project a pattern and i t will be like viewing the image through frosted glass. Some films seem more prone to Newton's rings on their lower surface then others, and I believe its thoughs films with shinney emulsions that indeed cause the mo st problems, eg. TMax, APX 25. Hope this is of some help. Let us know how things work out.

[Keith Baker]

The mysterious part is that I am NOT using a glass neg holder!

[neil poulsen]

Are you using filters designed for below the lens use? Perhaps you might try adjusting the filters a little and seeing if it moves the concentric circles that you've been encountering.

[Trevor Crone]

Keith have you made any prints without the below the lens filters, and do the "rings" print light or dark? It may be some form of flair perhaps from a worn diaphragm blade within the lens?

[Doug Paramore]

Keith: If you haven't already, made a contact print to make sure the rings aren't on the neg. Sometimes you can't see slight tone changes on the neg that show up quite well on the print. Are the rings at the same spot every time? Try a print without a filter. Is your Beselar teh type with a bellows above the negative carrier? If so, try moving it up or down to see if there is an improvement. Remove the filter and try different aperatures. I have never had a problem with below the lens filters, but I suppose its possible. Also, change the distance from the filter to the lens to see if you have reflection problems. Hope this helps,

Doug.

[Brian Ellis]

A little more information might be useful. For example, how many rings are there? Are they lighter than the surrounding area or darker? If lighter, then it seems likely that somewhere along the line something circular is getting into the light path. With the Besler MX series of enlargers and a cold light head, I believe the upper bellows should be fully compressed. If yours isn't, it's conceivable that something inside the upper bellows is interfering with the light path. Are your filters circular? If so, they might be the culprit. Finally, on the left side of the enlarger there is a holder that is designed to hold a red filter and that can be swung underneath the lens to allow you to see the print without exposing the paper. Although the filter that Beseler makes for this holder is square, Wthe interior of it is circular. When not in use, this holder is swung out of the light path. Is yours pushed fully to the left and away from you so that it is out of the light path?

[Keith Baker]

Thanks for the responses thus far. In order to settle the issue I went back to the darkroom. The Ilford filters are the problem. When I print with the filter the rings appear; When I print without the filters the rings are gone.

[Doug Paramore]

Try changing the distance from the filter to the front of the lens. You may be getting a reflection between the lens and filter of just the right focal length of screw things up. Also, make sure filters are spotless. I suspect the distance is the culprit.