Prints have dark border around them - Chromega D Dichroic II - Any Suggestions?

[jabe]

I am having an issue with an Omega D5500 enlarger with a Omega Super Chromega D Dichroic II head. I'm hoping someone here can help me out and point me in the right direction to figuring out the issue. I noticed the problem when I recently changed from a 6x7 light box and 105mm lens to a 4x5 light box and a 150mm lens.

When making prints, the outer edge of my image is about a half inch boarder that is approximately 1/3 stops darker than the rest of the print. Its a hard edge and almost looks as if there is a shadow around the sides of my prints. Its most noticeable in gradients such as the sky.

I'm wondering if I am suppose to be using a lens cone with my set up possibly?

Any information would be greatly appreciated. I will attach an example here as well. Its a crop of an image but you can see what I am talking about on the top and right side of the photo.

Thank you

 

[MattKing]

Which enlarger are you using the head on?

 

[jabe]

Which enlarger are you using the head on?

Sorry forgot to include that - Omega D5500

 

[L Gebhardt]

Looks like reflections off the edge of the negative carrier. Turn on the enlarger light and look up at the empty negative carrier through the lens board, without a lens, and see if you can see a bright reflection or light leak.

 

[Nicholas Lindan]

Looks like reflections off the edge of the negative carrier. Turn on the enlarger light and look up at the empty negative carrier through the lens board, without a lens, and see if you can see a bright reflection or light leak.

Easier to do with a mirror. It is an interesting exercise in any case - it shows where stray light* is coming from.

* "Stray light" is any light you don't want.

 

[MARTIE]

I had/have a problem with a 6x9 diffuser Bimabox for my Durst. It took me a while to figure out where the problem lay and fortunately, I have more boxes so I was able to just switch.
However, during the elimination process, the problem certainly wasn't visible on the white base board with a negative in the holder nor was it obvious without a neg and not knowing about it.
I seriously can't remember if it was actually noticeable even knowing about it or by inspecting the box itself, it seemed so subtle. Replacing the white diffuser material would have been my next step. Come to think of it, I believe Durst supplied a diff.1 and a diff.2 diffuser panel, the thicker diff.2 specifically being for colour printing for better/more even light spread and consistency.
I know your enlarger is not a Durst but perhaps my experience might be helpful. I know how frustrating these kind of things can be! Best of luck.

Sorry, just to add, to switch between vertical and horizontal formats a couple of things need to change on my Durst L1200's but I have no idea if that's the case on your enlarger.

 

[Doremus Scudder]

Check the diffusing box to make sure that all the styrofoam walls are in their proper place (they're just held in place with pins and can get shifted around with bumps). Also check the diffusing panel to make sure it is clean and properly positioned. The diffusing panels in the Chromega mixing boxes are very special; ground to be thinner on the edges than in the middle to counteract light falloff. If someone has replaced yours with a piece of plex or opal glass of even thickness, you'll get falloff (vignetting) around the edges. Center-burning can help.

Hope this helps,

Doremus

 

[jabe]

Thanks for the responses everyone. I am going to have a look at my enlarger tomorrow and run through all the possibilities.

Looks like reflections off the edge of the negative carrier. Turn on the enlarger light and look up at the empty negative carrier through the lens board, without a lens, and see if you can see a bright reflection or light leak.

I didn't really think about this. I am going to test it tomorrow and hope that may solve it...

Just to rule this out… what kind of easel are you using? Does it have flat “blades” or a ~1/4” frame to hold the paper down?

Could also potentially be reflections off the edges of the negative carrier (see post #4) or something else in there.

I'm currently using an Ultima 2 blade easel 11x14 easel

 

[tih]

Sure looks like michael_r is on to something with the easel suspicion. You've got the effect on two sides in that picture, and the Ultima has angled surfaces along two sides of the paper it holds, that look like any light they reflect would hit the paper the way we see in your picture. Changing from a 105 mm to a 150 mm lens means you now have the enlarger head higher, reducing the area hit by such a reflection, which may be why you're only noticing it now.

They're already dark grey, if the pictures I've found match yours, but maybe try painting those edges matte black, to limit reflection further?

 

[jabe]

It seems I have resolved the issue from what I can tell so far. It was my negative carrier..

For some reason the omega one I have is raw metal and was reflecting the light off the edges around where the negative sits and intensifying the light around the edges. I simply painted it with flat back nail polish and its looking good so far.

Thanks again everyone for the responses and ideas.

 

[Doremus Scudder]

... I simply painted it with flat back nail polish and its looking good so far. ...

Where does one find flat-black nail polish?

 

[MattKing]

Where does one find flat-black nail polish?

Skateboarding shops?