Are ALL 50mm 2.8 enlarging lenses AWFUL @ 2.8?

Bob Carnie · Jul 7, 2016

I use Apo Rodagon 50's for 35mm work, I focus wide open and then close down two stops. I use glass carriers and periodically check for alignment.

It is funny that even though I think I could print wide open, I am hesitant and will sometimes open up a half to keep my time under 25 seconds.
I just finished a project where I had to actually make one image with the lens wide open and a really long time and FWIW the print looked pretty nice corner to corner.

I think negative popping and negative carrier alignment are real issues to worry about , Also centering the negative to the neg carrier and light source(condensers) is really important.
I am not so convinced that the wide open aperture is so bad but I hold these beliefs that the corners may be sharper without real proof.

At one point I had all normal Rodagon 50's and I will admit I switched all of them to APO including all the larger lenses I use short of the 240 , 300 and 360 I have.
I don't think I could definitively say my work is better because of the change .

M Carter · Jul 9, 2016

This is one of those "anecdotal" threads where everyone pitches in their typical experience. In reality, just testing your lens at each stop during a printing session would take about 5 minutes, and you would know in a concrete way how a specific lens (not just a general lens model and brand but the actual lens you own, on your enlarger using your processes) differs from stop to stop. Like many long, drawn-out threads here, the correct answer would be one post: "test it yourself". (Not trying to sound snarky and I enjoy a good rambling conversation as much as the next guy!) (And I'm aware that the OP was a general question and not about a specific lens. But there is simply no correct "general" answer, is there?)

As far as 2.8 goes - it sure comes in handy with high contrast negs when lith printing. 3 minute exposures get old quickly!

Nicholas Lindan · Jul 13, 2016

As many have pointed out, APO lenses work well wide open or stopped down ever so slightly.

If you have a true point-source enlarger (a very rare item - and really quite useless for most purposes) you have to print wide open. The point source is focused so that it projects the negative image on the back of the lens. As a result stopping down is pointless and just results in chopping the corners off the image. If you stop down further just a circular spot will be left. It is normal practice to use a longer lens so the entire negative image is projected through just the center of the lens.

One could say with a point source you are always printing wide open whether you want to or not.

Thomas Bertilsson · Jul 13, 2016

It has been said more than once in this thread, but an APO enlarging lens will be far from awful wide open.

My Leitz V35 enlarger has a 40mm f/2.8 Focotar lens on it, and it works very well wide open up to about 10x enlargement.
It's good enough for me to be satisfied with the results, and while I'm not a real expert, the thing I most often get comments for when people view my prints is the print quality.

A really great enlarging lens will help add clarity to the print, and it really does make a difference. But nobody else can tell us what is good enough - we have to be the arbiters of what is good enough for our own work.

Bob Carnie · Jul 13, 2016

I think Thomas says it well, just finished some 16 x20 prints off Mamiya 7 system - 43mm lens.

Apparently this lens is kick ass, the photographer photographed in the pouring rain and the buildings were gleaming, not perfectly sharp I imagine due to the pouring rain situation, but quite beautiful in print quality.. razor sharp vs gleaming soft... sometimes I pick the latter.

wiltw · Jul 13, 2016

Mick Fagan said:
Geez Bill, I’m not so sure about that with regard to colour requiring a lesser designed lens for reproduction of prints....Essentially that test told me something that I hadn’t taken too much notice of, up till then that is. That standard 50mm amateur enlarging lenses from most manufacturers, generally, are designed to enlarge prints up to about 5x7” and not too much more. From then on the next range of enlarging lenses are designed to enlarge prints up to about 12x16” and not too much more. Very specialised and highly corrected Apo designed lenses are designed to enlarge prints to about 24x30” and a bit higher.

The largest prints I can remember doing direct from 35mm film, was done shortly after the release of Kodak Ektar 25 colour negative film. We did life sized colour prints of people...The resulting prints were displayed all over the place with huge emphasis on the fact that these were all enlarged from 35mm film. They certainly looked brilliant, as they should have, as the cost and effort into making these, was mind boggling. Think about 2-3 months of fiddling, on and off, before everyone was happy.

Mick.

Thx much for a fascinating read, Mick.

Your observations about optimization of a range of lenses to a size range certainly matches up with data sheets/brochures from the lens manufacturerer that I had read. I have something from Rodenstock that mentions the 'sharpness' characteristics optimized for an aperture size range assumption which is needed for reasonable enlargement exposure time within that size range of enlargements. So the more 'professional' lens assumes that it is stopped down 1-2 f/stops for best control of abberations, while the more 'hobbyist' lens assumes it is stopped down 3-4 f/stops for light intensity control with smaller prints that hobbyists print. As michael_r said in this thread, "for the 50mm f/2.8 Apo Rodagon, Rodenstock indicates you only need to close down one stop for maximum image quality".
And f/2.8 is to permit more accurate focus and easier focus especially at the long distances -- lower image intensity at that distance -- for the very large prints, with the lens stopped down slightly for improved abberation control at the edges.

Are ALL 50mm 2.8 enlarging lenses AWFUL @ 2.8?

Bob Carnie

M Carter

Nicholas Lindan

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Thomas Bertilsson

Bob Carnie

wiltw

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