210mm for 8x10"

[Oren Grad]

I have read on multiple occasions the supposition that Schneider et al. limit IC specifications to a more rigorous standard for process lenses. Is it possible this was done for the G-Claron line of lenses? I am guessing the actual MTF charts are not available. If so, I think it's a bit of a stretch to blindly follow the stated IC, especially for a lens not sold originally as a general-use camera optic (right?).

See attached - though I suspect these will generate more questions than answers. Sorry, I don't have the 210 data.

[Corran]

Interesting. If I am not mistaken, those look like the newer Plasmat design lenses?

[Oren Grad]

I downloaded those from the Schneider website in 2004, thus during the period when they were selling the plasmat version.

[Drew Wiley]

All later G-Clarons sold in shutter were plasmats, but better corrected for close-range than general-purpose plasmats. My spec sheet only lists the plasmat construction. Unfortunately, the image circles are only given at 1:1 or 1:2 @ f/22, just like graphics applications, even though the parallel Schneider marketing brochure from the same period recommends G-Clarons for tabletop studio applications. I wonder if alternate constructions were even still being made past the 60's or 70's. Around here at least, Goerz and then Nikkor dominated the process lens market.

[Bob Salomon]

All later G-Clarons sold in shutter were plasmats, but better corrected for close-range than general-purpose plasmats. My spec sheet only lists the plasmat construction. Unfortunately, the image circles are only given at 1:1 or 1:2 @ f/22, just like graphics applications, even though the parallel Schneider marketing brochure from the same period recommends G-Clarons for tabletop studio applications. I wonder if alternate constructions were even still being made past the 60's or 70's. Around here at least, Goerz and then Nikkor dominated the process lens market.

Drew, Rodenstock was the dominant supplier of graphic arts lenses for horizontal process cameras with the Apo Ronan series.
Vertical process cameras used wide field lenses from Nikon, Schneider and Rodenstock. But for horizontal Rodenstock had a massive lead!

[Drew Wiley]

I've never even encountered Apo Ronars except in shutter for view camera use, Bob. All the big print shops around here used Apo-Nikkors, or else older Goerz, on their big horizontal cameras. Maybe because we're on the Pacific and a lens thrown into a bottle in Japan drifts here sooner than one thrown into the Atlantic! The only common Rodenstocks were cheapo wide-angle versions on stat cameras for casual applications like T-shirt silkscreen shops, perhaps rebranded Geronars. And from what is
ordinarily up for sale on Fleabay, Apo Nikkors seem more common than barrel Apo Ronars... or maybe Apo Ronars got retrofitted with shutter more often for photo use, and this has skewed the proportions. Dunno.

[Bob Salomon]

I've never even encountered one of those, Bob. All the big print shops around here used Apo-Nikkors, or else older Goerz, on their horizontal cameras. Maybe
because we're on the Pacific and a lens thrown into a bottle in Japan drifts here sooner than one thrown into the Atlantic! The only common Rodenstocks were rebranded cheapo wide-angle versions on stat cameras for casual applications like T-shirt silkscreen shops.

Then you haven’t visited enough of them, Rodenstock was by far the leading supplier.

[Pere Casals]

IIRC Schneider and R'stock both say that coverage ends where MTF has fallen to 10%.

10% at how many cycles/mm?

[Tim V]

I have the older Dagor type 210mm G-Claron. I bought it knowing that I would need to upgrade eventually, but it's the best I could afford to get me going right now. I want a Kowa-Graphic, but I only ever see them up for sale for over $1000USD! (I live in NZ, so it's not possible to find anything local for private sale, meaning flea-bay, international stores or private sale here it is.)

It is possible that some of the deficiencies I've seen regarding sharpness are also due to film flatness and / or slight camera shake (I really should upgrade my tripod. It's perfectly rock solid for 80mpx digital capture, but the 8x10" is a wind sail.) Anyway, I'm not talking specifically about the corners being soft, but the edges, eg left/right on landscape orientation being noticeably softer under magnification. If it were just the corners then I'd accept it, but as it's the edges I wonder if my copy of the lens is performing as it should.

I know it's a really hard focal length for 8x10", but it's also my favourite! The contact prints are lovely, it's just I'd love to be able to drum scan them for large prints in the future.

[Dan Fromm]

10% at how many cycles/mm?

Papi, take a look at the data sheets Oren posted. They're more evidence that my memory is failing.

To answer your question, they all show MTF @ 3, 6, and 12 cycles/mm. If I'm reading them correctly, all three of the lenses do better than I believed to the limits of their claimed coverage at f/22 at infinity at 12 cy/mm. But 12 cy/mm isn't much, the interesting question is how well they do at higher frequencies.

Tim, Dagor type G-Clarons are minor cult lenses. You can probably net enough from selling yours to replace it with a plasmat type, if that's what you want, with some funds left over.

Tim when you look at negatives, remember that diffraction is worse off-axis than on-axis and that the diffraction limit Pere Casals quoted is on-axis. 45 lp/mm will start looking fuzzy at magnifications a little greater than 5x. You may be asking for more sharpness than is possible at f/45.