240mm f9 Beseler Apo-HD enlarging lens problem

[brucetaylor]

I have finally, after well over a year, gotten my new-to-me Omega F 60's era 8x10 enlarger up and (mostly) running. It had been neglected in a seaside environment and required a great deal of cleaning.

I knew I was going to be compromised with height when my darkroom build area changed, and I bought a 240mm f9 Beseler Apo-HD enlarging lens from someone on this forum as a hedge against height issues. After full reassembly everything was way out of adjustment (and nothing focussed!). Using the Versalab laser tool and some fiddling brought everything parallel I was able to get good, sharp focus with my Schneider 300mm enlarging lens up to about 16x20 wide open. The old condenser head hits the ceiling at this point.

So I temporarily (cardboard) mounted the Beseler 240mm, aligned it, and everything out towards the edges smears, the edges never in focus wide open. It improves somewhat when stopped down. So I iris-mounted it on my Deardorff and found the same thing on the gg, the center will be sharp but the outer third of the image will never come into focus no matter how the camera is racked. Anyone have ideas? The lens doesn't look as though it has been worked on or damaged, in fact it looks nearly new. I really want to go to 16x20 and I would like this lens to work. Ideas welcome!

Bruce

[Drew Wiley]

Maybe the cardboard isn't flat or stiff enough to maintain alignment. But that particular lens is regarded as a "bargain" brand. I was really intended for cheap "stat"
process cameras like those once used in silkscreen T-shirt shops.

[Bob Salomon]

That particular lens isn't an enlarging lens. Since the Beseler enlarger did not allow a large enough hole for a true enlarging lens like the 240mm Rodagon they decided to private label a Rodenstock wide field process lens as the Apo Enlarging lens. Since it is really a process lens it was optimized to deliver best performance at f22.

You would be much better off optically to buy a proper enlarging lens rather then this compromise lens.

[Jac@stafford.net]

The 240mm f9 Beseler Apo is not really an enlarging lens. I personally won't use an F9 or larger (numeric) F-stop lens for enlarging. Change the lens and be happy.

[ic-racer]

Using a Peak 1 magnifier to view the grain, side by side comparison of my Componon-S 240mm vs 300mm lens is quite dramatic when both are wide open (f5.6). The 300mm is sharp right up to the corners of the 8x10 negative. The 240 is obviously blurry at the corners wide open. When stopping them down to f16 or f22 and making prints the corners of the prints are fine when observed with the unaided eye.

So, as Bob suggests, try some prints at f22 and see how they come out.

[brucetaylor]

Aha! Thank you all for the information, I can see why it would function differently from the true Schneider enlarger lens (which is huge in comparison) if it was a re-purposed process lens. I will give it a try at f22 and see what I get.

[Bernice Loui]

Very possible this lens is defective or damaged in some way. Given the camera test, it should produce a sharp image on the GG at the same reproduction ratios. This is why each lens should be tested and individually verified for proper performance before accepting it.... even it it appears "new".

Suggest trying another 240mm lens if possible.

While a 240mm lens is not ideal for 8x10, it's performance at the edges should not be this poor even at f9.
Beyond the problem of coverage, the problem of light fall off can become more significant as the enlargement size goes up. If the mechanical constraints are serious, consider a wide field process lens as these will have enough coverage at the magnification ratios noted (8x10 original to 16x20 print), still light fall off can still be a problem.

Do check for any possible item in the light path that may be causing an obstruction. This includes a condenser that is not matched or properly set up to the focal length of the enlargement lens. On the Durst 138 & 184 condenser head, there are several condenser available that are mixed an matched in pairs for a given enlarger focal length. If these are not set up properly for a given lens, there will be image projection problems.

IMO, use the longest focal length possible for making enlargements ( I use a 240mm f9 APO Artar for 5x7/13x18, tried a 210mm f5,.6 Compoon S and did not like the results or 180mm f9 APO Nikkor for 4x5, tried a 150mm f5.6 ELNikkor did not like the results), the results are often better than using a shorter wide field lens for making enlargements. As for using APO process lenses in enlargers, been doing this for years and years. The good ones (APO Artar, APO Nikkor, APO Ronar and..) work extremely well as enlarging lenses for large negatives. Check the projected image using a long mirror Peak grain focuser from center to each corner of the projected image. It must be absolutely sharp with good resolution of the film grain edges from center to each edge. Anything less than this will not result in a sharp and properly defined print. Do test the set up for light fall off and quality of illumination. There will can be problems with the film carrier, mechanical alignment and all else in properly setting up a LF enlarger. Also make absolute sure the column is stable, rigid and in proper alignment from the lowest to highest enlarger head position relative to the table.

These APO process lenses should produce excellent images at f16 to f22, at f32 the image quality falls off. Print exposure times should be 20 to 40 seconds overall. If exposure exceeds much over 60 seconds, a stronger light source should be used. Far beyond 60 seconds the print paper will begin to exhibit reciprocity sensitivity/exposure problems much like film.



Bernice



I have finally, after well over a year, gotten my new-to-me Omega F 60's era 8x10 enlarger up and (mostly) running. It had been neglected in a seaside environment and required a great deal of cleaning.

I knew I was going to be compromised with height when my darkroom build area changed, and I bought a 240mm f9 Beseler Apo-HD enlarging lens from someone on this forum as a hedge against height issues. After full reassembly everything was way out of adjustment (and nothing focussed!). Using the Versalab laser tool and some fiddling brought everything parallel I was able to get good, sharp focus with my Schneider 300mm enlarging lens up to about 16x20 wide open. The old condenser head hits the ceiling at this point.

So I temporarily (cardboard) mounted the Beseler 240mm, aligned it, and everything out towards the edges smears, the edges never in focus wide open. It improves somewhat when stopped down. So I iris-mounted it on my Deardorff and found the same thing on the gg, the center will be sharp but the outer third of the image will never come into focus no matter how the camera is racked. Anyone have ideas? The lens doesn't look as though it has been worked on or damaged, in fact it looks nearly new. I really want to go to 16x20 and I would like this lens to work. Ideas welcome!

Bruce

[brucetaylor]

Thank you Bernice for this additional information.

In the back of my mind I was wondering about the possible effect the condensers might have when using the shorter focal length lens, perhaps that is at work here as well.

And yes, I did think about possible damage or defects in the lens no matter its appearance. I work with a lot of old equipment, and mint appearance doesn't always mean an item works as it should-- it could simply be a dud.

I just remembered I have a 210mm process lens that covers 8x10, I think I may try it on the enlarger just to see if I have the same type of issue.

Dealing with the mechanical problems (head height) may be the solution. I have a much shorter color head that will take some fiddling to mount, but that may be the solution, ultimately.

Bruce

[Nicolasllasera]

I have the same lens you have and no issues enlarging 8x10 to 12x16. I do usually stop it down to f/22 or so. But at f/9 it looks ok on the corners.

[Drew Wiley]

First of all, that's only a 1.5X enlargement. Second, to properly judge the corners you need exactly the right focus magnifier, namely the Peak pro one with the tilting
mirror. What is "acceptable" and what is "ideal" in enlarging lenses just depends on your personal standards and exactly what you are doing.

[Neal Chaves]

I think you may have bought that lens from me, but in any case I made many good prints from the one I did sell. I made no prints larger than 11X14 from 8X10 negatives on a Beseler 8X10 45VXL with a daylight tube. I filter for VC using only a Roscoe Y or M gel, so the light output is quite strong. Most of my prints were probably made at f22 or smaller.

I bought that enlarger and lens from David Mendelsohn, also a member here. He made many outstanding large prints, 20X24s, with that same lens. I only sold that Beseler HD because I found an easy way to mount the 240mm and 300mm 5.6 Rodagons. I see no difference in the prints I made with the Beseler and those I make now with the Rodagons,

If you don't like it, you can sell it again easily because for those who are not handy with a sabre saw or a Dremel, or do not care to spend a lot of money at S.K. Grimes, it is the only lens for 8X10 converted Beseler enlargers.