bad definition with omega enlarger

[Martin Santos]

Hello all.

I'm enlarging with an Omega B-22 enlarger, with Omegar lenses (50mm for 35mm, 75 for 6x6).

Now I'm trying very large enlargements (50x60cm), and discovering that the images have are really crisp just at the center of it. Ever the dust particles at extremes are not round, but out of focus and oblongued.

This can be a problem of the enlarger or from the lens? (I tried it at f5,6 and f11). With tje 75mm lens is happening something similar, but anyway this lens is in very bad shape.

I never got another lens fot the Omega, because it doesn't have the usual thread, but a very smaller hole. And here in Brazil, where I live, I never found another lens for it.

Thanks in advance for any help!

Regards,

Martin

PS: This is my very first post here. I think that I'm at the right forum to make this question!

 

[TheFlyingCamera]

Martin-

it sounds like a lens issue. Those lenses are very basic lenses and are not really meant for doing enlargements that big. You're running into the edges of the field of coverage for the lens - they sound like they're not true flat-field lenses and only have sharp coverage at the center of their field of view. I would look on Ebay or check with B&H Photo for some better lenses - El-Nikkors are probably the best alternative unless you have an unlimited budget. I suggest B&H because I know they do a very large volume of business with Brazil, and even have a portuguese version of their website, so it should be easy to get what you need from them.

 

[David A. Goldfarb]

There are a few possibilities--the alignment of the enlarger, the quality of the lens, and negative "pop" due to heat.

There are laser alignment tools for very precise alignment, but you might start with a bubble level and seeing if the baseboard, lens stage, and negative stage all seem level.

Most enlarging lenses use M39 (Leica) thread. Are you sure yours is different? If you've got a very old enlarger, I think some enlarging lenses were M22 or something like that.

To see if you've got a heat problem, put a neg in the enlarger, focus it quickly, and wait a minute or so, and see if it pops out of focus. Solutions for this are heat absorbing glass, usually in the filter drawer or elsewhere above the condensors, or a glass negative carrier.

 

[Rick A]

What brand of lenses, and what mounting size? Have you tried stopping down further, to f16 or f22. I use 25mm mount lenses quite a bit, and haven't had that problem. I can see where you might have some fall-off with the 75mm and 6x6 negs, I normally use an 80mm and a 90mm for 6x6. I havent experienced it with my 50mm with 35mm negs. Is it possible the condensors are misaligned? You may be beyond the reasonable limit of enlargment for those lenses, they may only be good up to 11x14inch. It very well may be that you need better quality lenses for that large of sizes. Schneider Componon S or similar Rodenstock or Nikor glass will get you there. You will have to either buy new lensboard for Leica mount or find the lenses to fit what you have.
BTW, welcome to APUG, you are in the right place.

 

[lightwisps]

Martin, I hate to tell you this, but Omagar lenses are far from the top of the line. Do you have a good Focus Scope? If so, try to see how the focus changes from edge to edge. If the problem is only on just one side it might alignment, but if it good center but not on any edges then it is probably the lens. Look for either El Nikors or Componon S lenses. Should be not all that expensive and worth the cost. Don

 

[ic-racer]

As others have suggested, this is a problem with medium-low grade lenses. That is , they are OK when just using the center of the image circle, but when you use the edges of the image circle (as in a higher magnification enlargement) the quality suffers.

 

[fotch]

Hi Martin, welcome to APUG. Several things, which already have been stated could be a factor, however, start with a better lens, preferable a 6 element lens such as the Nikon 50mm F2.8 and go from there.

 

[L Gebhardt]

The first thing I would check is the enlarger alignment. Then the quality of the lenses. If you can focus the sides to make them almost as good as the center (but not at the same time obviously) then you have an alignment issue. if they look like crap no matter what the focus then you need a new lens.

 

[Ronald Moravec]

You need a good lens, a flat negative which usually reqires a glass carrier, and well aligned enlarger. Then you have to focus it.

If any one or all are lacking, you get defective prints.

 

[Martin Santos]

Thanks a lot for all of you!

I will try to align the enlarger - ever if it looks very very solid, and never was altered since it was bought (1960?). I never found another lenses to try in it, but maybe I can try to make a support for my cameras's lenses (Summitar).

A doubt: the condenser system can be desaligned and cause this out of focus zone? Or the condensers out of alignment can just make zones darker? (It is the only thing easy to remove, and i do this from time to time to clean the condensers).

Regards,

Martin

 

[L Gebhardt]

To the best of my knowledge the condensers don't play a role in focus, only in the evenness of the illumination. If you haven't ever checked the alignment, that would be my guess.

 

[George Collier]

I used to have a B-22, and my guess is that there is some buckle, or "pop" occurring, as David suggests, meaning that the center of the neg is raised up from the heat, which it can be with a B-22. Stopping the lens down to a smaller aperature can help with this. If it works, but is too small (times too long) at least you know what the problem is. Also, it's best not to use an f/stop more than 2-3 down from the largest.
My B22 had corner set screws on the negative stage I could use to level it. A simple method, which I used in college, was to take a piece of film the size you are using, make it black (expose to light and develop) - if 35mm, a leader works. Then scratch a big X corner to corner, then adjust the corner set screws till all corners are sharp. If the center isn't sharp, then you have buckling.
For a better lens, like an El Nikkor, you can get another lens board cut for that size, which, I believe is 39mm, called "Leica" thread. There is a well known web site for vintage Omega enlarger parts, I forget the name, maybe someone can help with that.

 

[5stringdeath]

I have two B-22's ... the first thing you need to do, as suggested, is replace those Omegar lenses. They really arent' very good, especially when you are enlarging as big as you want.

Two good sites for Omega info are:

http://www.khbphotografix.com/omega/

http://www.classic-enlargers.com/

 

[jp498]

You can get lens boards with various sized holes for various lenses. 39mm is a common size. I bought one recently on Ebay for very little money. The lens board is the metal plate with two aluminum knobs on it holding the lens to the parts that move with focusing. You want a lensboard with a hole size that matches the intended lens. You can also drill out yours to be bigger if required for a new lens. Clamp it between two pieces of wood and drill right through the whole sandwitch with a hole saw.

A used el-nikkor or schneider componon-s would be high quality and pretty affordable replacement lens.

 

[archer]

Dear Martin;
I agree with most of the responses to your question. It is undoubtedly the quality of your lens, where the problem lies. Just a word of advice, if you are making very large prints from 35mm negatives, a glass negative holder is really essential to squeeze the last bit of sharpness from such a small negative. If you don't have one, you can use the glass from a Gepe 2 1/4 glass transparency (slide) mount. The top glass is anti newton ring glass and both pieces of glass are very thin. I have made prints as large as 32in X 40in from 35mm and from the proper viewing distance they are very sharp even to the corners.
Denise Libby