Omega D5 Pro-Lab with Condenser Head light spill problem

[3p77pffEpYupg26BXciU]

I have a Omega D5 Pro-Lab enlarger with condenser head that I purchased used recently which has an odd problem: when I have a negative carrier installed and focused (and the enlarger on) there is a sharp rectangle of light projected through the negative carrier onto the easel as you'd expect, but there is also a faint, but obvious circular pool of light that is the same diameter as would be projected if the negative carrier was not installed. It is almost as if the negative carrier was slight translucent... I've tested multiple negative carriers both black metal and black matboard and they all exhibit the same problem. The pool of light is definitely strong enough to fog a print unless the easel arms completely block the non-printed portion of the paper. I've tried multiple lenses and they all show the problem, though with some it is more pronounced than others. The problem is more or less pronounced depending on the lens aperture, but it is there for all apertures. I've also tried both a standard flat lens board and a three lens turret, the problem shows up with all. And I've tried multiple bulbs, both 75W and 150W - all exhibit the same problem. I've verified that the condenser is installed problem and the alignment appears to be good; though it might need some slight adjustments, I can't account for this behavior on the basis of alignment. (Though of course that doesn't mean I'm right.) (I've checked another D5 enlarger at a local photo lab and they have no such issue).

I've included two images with this post. These are simulations of the problem. The first simulates the pool of light without the negative carrier - this is clearly just a white pool of light on a black background. The second simulates when a negative carrier is installed. Here you see the sharp bright rectangle you'd expect, but also a faint pool of light the same diameter as the previous pool of light. It is that faint pool of light that I'm concerned about.

Has anyone ever seen something like this before? Does anyone have any ideas what could possibly be causing this problem? I've asked several photography friends, some with decades of experience, but no one has an answer. Any help or suggestions would be greatly appreciated.

Many thanks,
John.

 

[bernard_L]

I've tried multiple lenses and they all show the problem, though with some it is more pronounced than others.

I would check the enlarging lenses for dust, fog, etc... Stare at the exit side of the lens against a dark background; shine a small flashlight from the other side, off-axis.

(...)circular pool of light that is the same diameter as would be projected if the negative carrier was not installed

Can you confirm specificallly this?

Anything else (apart from lens) in the light path between negative carrier and easel: red filter, under-lens VC filter?

 

[Rick A]

The big question is, does it do this with a negative in place? I have a D-6 which is basically the same machine, and I don't have this issue. My guess is it won't happen with a neg in place or at least won't be as pronounced. I think what you are seeing is light reflection from the easel to the lens and back to the easel when there is no negative in place, which would allow for easier notice of the effect.

 

[MattKing]

Are you using the Omega Masking attachment?

Do your negative carriers have the protruding ring, or are they completely flat?

 

[ic-racer]

Take of the lens and look up there. Now you can see if lens is just projecting an image of the underside of the frame where the bellows attaches. Many enlargers have a circular opening up there. The other common finding is that some lenses have considerable off-axis light spill. I know just about every Componon and Componon-S I have exhibits this. If you look into the lens (when the enlarger lamp is on) from just beyond where the negative opening projects and you can see exactly where the light is coming from inside the lens. This off-axis light usually only causes problems if it bounces off your baseboard, on to a wall and back onto the paper. It can also fog paper on the area outside the easel blades.

 

[3p77pffEpYupg26BXciU]

Hi all - thank you for the suggestions. Regarding the lens, the light spill occurs with all of my lenses and the lens of a friend that I tested on this enlarger as well. While that doesn't absolutely rule out the lens, it makes it seem unlikely. I have nothing in the light path below the lens (except the easel, of course). The problem occurs whether I have a a negative in the negative carrier or not and occurs whether or not I'm using the Omega Masking attachment. Some of the negative carriers I'ver tested with have two small tabs on the underside to help position the carriers while others are completely flat. The problem occurs with all of them.

bernard_L - yes, I can confirm that the light pool is the same diameter as is the case when no negative carrier is installed. I'll try the flashlight idea to see if I can replicate the problem that way.

Rick A - Regarding light potentially bouncing back from the easel, based on the testing I've done so far I doubt this is the case, but I'll look into it further.

ic-racer - Some of my lenses are Componon, though I also have a Roganon and an El Nikkor and the problem is there for all of them. But I'll try your suggestion of looking to see if I can actually see the light spill through the lens.

I'll try these tonight and post the results.

Thanks again for the suggestions and interest,
John.

 

[MattKing]

If you adjust the position of the masking arms on the Omega Masking attachment is there an affect on the extraneous pool of light?

 

[Jim Jones]

It may be light reflected from interior surfaces between the negative carrier and the lens.

 

[3p77pffEpYupg26BXciU]

Thanks again for the suggestions. I've done more experimenting and sadly nothing has solved the problem so far.

bernard_L: I tried shining a flashlight off-axis as you suggested and while the lenses needed a bit of cleaning (some more than others) after cleaning the problem is just as bad.

Rick A: To test your theory I blocked all the light coming direct through the negative carrier yet did not block the entire lens and the problem still occurs.

MattKing: I tried using the Omega Masking attachment to adjust the opening and the pool of light remains the same size. If I make the opening very small then the pool is very dim, but it is still there.

Jim Jones: You could very well be right. Everything in that stage appears to be stock-standard, and while all are black the surfaces are at least somewhat reflective. I've tried using a flat black cloth to mask the interior but it didn't seem to make much difference. However my guess is that I'm just not masking enough yet.

Does anyone have any ideas of how I might be able to make the bellows a flatter black?

I've noticed that in some situations (depending on the lens used and the height of the enlarger head) the pool of light is larger than the projected light without a negative holder. Also depending on the aperture setting, the pool of light sometimes has a ring of brighter light at its edge, then dimmer light until the hard edge of the light projected through the negative carrier. Maybe these additional symptoms will be meaningful to someone...?

Thanks again,
John.

 

[ic-racer]

. Also depending on the aperture setting, the pool of light sometimes has a ring of brighter light at its edge, then dimmer light until the hard edge of the light projected through the negative carrier. Maybe these additional symptoms will be meaningful to someone...?

Thanks again,
John.

Yes, that is off axis light. There is frequently a black metal ring that is part of the uppermost lens group. It shines the light pretty brightly (as if it were a bright metal surface, even though it is black) on most of my older Componon-S lenses (and lenses of other brands to some extent). Just look up there (put you head down by the baseboard where the ring of light shines and look up into the lens) and you can see it. It is pretty obvious but not much to do about it.

 

[3p77pffEpYupg26BXciU]

Yes, that is off axis light. There is frequently a black metal ring that is part of the uppermost lens group. It shines the light pretty brightly (as if it were a bright metal surface, even though it is black) on most of my older Componon-S lenses (and lenses of other brands to some extent). Just look up there (put you head down by the baseboard where the ring of light shines and look up into the lens) and you can see it. It is pretty obvious but not much to do about it.

Thanks ic-racer, I think you're right. I'm hoping to find some way to flock (or similar) the interior so that this will no longer be a problem. My wife's work is such that we really need the enlarger to not have this issue.

John, I'm not familiar with your enlarger, so I can't be much help. I could spend hours/days trying to crack the code for your pseudonym, but I know it would be time wasted.

Yes, you really shouldn't bother - it is simply a random string - I use random strings for my usernames and passwords to lessen the chance of my accounts being compromised. (I'm a payment security professional by day.)

-=-=-

Thanks all for your help and suggestions,
John.

 

[ic-racer]

Thanks ic-racer, I think you're right. I'm hoping to find some way to flock (or similar) the interior so that this will no longer be a problem. My wife's work is such that we really need the enlarger to not have this issue.

Yes, this light is bright enough to fog paper if making big borders etc. You may just have to experiment with various lenses to find the best one. I have about 15 enlarger lenses. Seems the metal black bodied Componon-S lenses I have show brightest ring. The newer plastic bodied Componon-S lenses I just tested show the effect less.