Performance of process lenses wide open?

[John Kasaian]

I've never tried this, but maybe one of you have---what sort of performance could I expect from an f/11 process lens shot "wide open" at f/11 as opposed to stopped down a few stops? Are process lenses optimized for use wide open or does stopping down improve performance ( being used as a "taking" lens on a field camera rather than aboard a process camera?)

What I'm wondering about is if it would be worth having some waterhouse stops cut for an old process lens

[Michael Darnton]

You might find this page pretty interesting. I certainly did. He suggests that a lot of LF lenses like being wide open:
http://www.hevanet.com/cperez/test/BigMash210.html

[Michael Darnton]

http://www.hevanet.com/cperez/test/BigMash210.html

Hmmm. I thought I posted this, but it seems to be missing. The above discussion seems to indicate that a lot of LF lenses like being used wide open.

Incidentally, I had an 210mm f10 apo-Raptar I was using for some rather critical work, at between 11 and 16 (basically a half-stop down), and I switched to an N-Sironar, thinking I was going to get some sort of nice bump in quality. Nope. So I do tend to believe the linked article.

[Donald Miller]

Process lenses, by and large, are optimized for flat field performance. Schneider recommends that their Repro and G Claron lenses (originally designated as process lenses...later shutter mounted for photographic purposes) will perform the best for the later purpose at F 22 and below. So in view of that, I guess an answer to your question would entail the photographic subject matter. I don't know how this applies to other mfg process lenses...just to Schneider's

[Sheldon N]

I've shot my Fuji 240A (process design) wide open, and am stunned by how sharp it is.

[Struan Gray]

I shoot my f9 Apo-ronars wide open quite often, and very often at f11. Likewise my Germinar-W. I have also done this with less exalted dialyte process lenses like my old APO-Lustrar. All 240 mm or longer, so I'm not testing the limits of the image circle.

They look good. A certain amount of double-line bokeh in background highlights, but nothing obtrusive. Sharpness is much better for the later lenses (80s-90s) compared to the older ones (60s-70s). They're equal at f22, but at f9 the later lenses win. That said, all are sharp enough for my purposes.

See 'Tanglings' my website, mostly shot with a 420 APO-Ronar or 240 Germinar-W at f11 or wider.

[Dan Fromm]

John, it depends on the lens.

On 2x3, f/9 Apo Nikkors (305, 420, 480) are all usable from f/9 down; 210/9 Konica Hexanon GRII is usable from f/9 down, noticeably better at f/11; 150/9 Apo Ronar is usable wide open, doesn't improve much on stopping down; f/10 Apo Saphirs (135, 180, 240, 300, 360) are all usable from f/10 down, better at f/16; 260/10 Nikkor-Q (= Process Nikkor) is usable wide open, better at f/16; f/9 TTH process tessars (6" Cooke Copying, 10.16" Taylor Hobson Copying, 30 cm Apotal) are usable wide open, better at f/16. 210/7.7 Beryl S, not really a process lens even though sold for use in copy machines, is usable wide open, better at f/16. All of these are worse at f/22 than at f/16.

14"/10 Wray Process Lustrar Ser. II is usable only at f/22 and smaller, I don't use it at all.

I've tried three 240/9 dagor type G-Clarons, two 210/9 Apo Gerogons on 35 mm. All are fine wide open.

John, everyone says that process lenses are made to be used at f/22. This because residual aberrations and field curvature are pretty well gone at f/22. I think it comes down to a question of coverage.

For me, wide open is usually ok unless I need to stop down to get more depth of field but that's because my applications don't need much coverage. I suspect that if the format's diagonal is near the lens' focal length then sharpness in the corners will be usefully better at f/22 than wide open.

If we're lucky, Joerg Krusche will report on his process lenses. AFAIK, he has more process lenses than the rest of us put together.

[Joerg Krusche]

John, it depends on the lens.

On 2x3, f/9 Apo Nikkors (305, 420, 480) are all usable from f/9 down; 210/9 Konica Hexanon GRII is usable from f/9 down, noticeably better at f/11; 150/9 Apo Ronar is usable wide open, doesn't improve much on stopping down; f/10 Apo Saphirs (135, 180, 240, 300, 360) are all usable from f/10 down, better at f/16; 260/10 Nikkor-Q (= Process Nikkor) is usable wide open, better at f/16; f/9 TTH process tessars (6" Cooke Copying, 10.16" Taylor Hobson Copying, 30 cm Apotal) are usable wide open, better at f/16. 210/7.7 Beryl S, not really a process lens even though sold for use in copy machines, is usable wide open, better at f/16. All of these are worse at f/22 than at f/16.

14"/10 Wray Process Lustrar Ser. II is usable only at f/22 and smaller, I don't use it at all.

I've tried three 240/9 dagor type G-Clarons, two 210/9 Apo Gerogons on 35 mm. All are fine wide open.

John, everyone says that process lenses are made to be used at f/22. This because residual aberrations and field curvature are pretty well gone at f/22. I think it comes down to a question of coverage.

For me, wide open is usually ok unless I need to stop down to get more depth of field but that's because my applications don't need much coverage. I suspect that if the format's diagonal is near the lens' focal length then sharpness in the corners will be usefully better at f/22 than wide open.

If we're lucky, Joerg Krusche will report on his process lenses. AFAIK, he has more process lenses than the rest of us put together.

Hi Dan,

I agree with your findings and conclusions, the smaller the format and the lower the picture angle the less stopping down is needed to obtain even quality across the image. In order to obtain max sharpness one may stop down a bit .. say 11-16 .. this will give performance that is equivalent in the center to very reputable MF lenses such as 250mm Sonnar for blad/Rollei SL66 or Apo Tessar 8/500 for the blad, both these lenses used as reference. The conclusion to stop down a bit can also be drawn from the study of MTF curves at various f-stops. But ... how much you stop down is a matter of personal preference .. whether a picture appeals does not depend on resolution .. but if the amount of detail is critical for you .. then stopping down depending on format used is good practice.

Dan, re number of process lenses .. that is certainly not true .. but in the unlikely case that someone is interested in some NIB's .. drop me a pm .. perhaps I may help with some advice.

Best

Joerg

[Joerg Krusche]

I shoot my f9 Apo-ronars wide open quite often, and very often at f11. Likewise my Germinar-W. I have also done this with less exalted dialyte process lenses like my old APO-Lustrar. All 240 mm or longer, so I'm not testing the limits of the image circle.

They look good. A certain amount of double-line bokeh in background highlights, but nothing obtrusive. Sharpness is much better for the later lenses (80s-90s) compared to the older ones (60s-70s). They're equal at f22, but at f9 the later lenses win. That said, all are sharp enough for my purposes.

See 'Tanglings' my website, mostly shot with a 420 APO-Ronar or 240 Germinar-W at f11 or wider.

Struan,

I like your 'Tanglings' .. very quiet .. just beautiful,

Joerg

[Struan Gray]

Thanks Joerg, it always feels great to make a connection.