My point was more that the G-Claron's are Repro lenses and not optimised for Infinity or normal use,of course there were Repro Dagors to. In many cases that in itself may make little difference but there can be problems.
Originally Posted by sanking
One problem with any Graphics/Repro lens is they are optimised for flat field work usually at 1:1 and in the case of the G Claron best between 5:1 and 1:5.
While Schneider state they can be used for normal photographic work they state they can be used up to an angle of view of 64 degrees, less than a Symmar or Sironar.
The image circle might be much greater but there are issues of spherical distortion using process lenses at or near infinity. This may be an problem at the edges/corners, obviously some designs will be worse than others.
It's possible that the early Dagor type Claron's are better than the later Plasmat designs in this respect but they still aren't optimised for normal use.
Some years ago I owned and used mostly vintage lenses for my ULF work. That included several uncoated Dagors and Protars. When I replaced one of the uncoated Dagors with a modern multi-coated Nikkor M lens I had to decrease development time by about 25% to account for the much greater contrast of the multi-coated lens.
Originally Posted by Steve Hamley
That said, the single coated Dagor design G-Claron lenses are great value. Late model coated Dagors of the same vintage, Kern for example, generally sell for a lot more than the Dagor type G-Clarons, in part I think because not many people are aware of the fact that early G-Claron are in fact Dagors.
As for the ultimate in contrast, try a multi-coated Dagor, say the 14" Kern Dagor or the Schneider 550 XXL. With only four air to glass surfaces and multi-coating you get a very contrasty negative with these lenses.
There's an exchange between Paul Strand and Ansel Adams, published (IIRC) in AA's Letters.
Strand had his prized Dagor coated after WW2, and it forced him to change his way of shooting: single coating a Dagor (or Protar) removes the flare from the deepest shadows which affectively provided the Zone I density; like a single exposure unit of Pre-Exposure. To compensate, Strand (and all of us since) had to double his exposure. A MC lens might approach a two Zone loss of density compared to an uncoated Dagor/Protar.
The higher up the scale, the less the effect of flare. By Zone III, flare is non-existent. But an uncoated lens is perfectly capable of extremely contrasty results. Only when we compare contrast side-to-side, do we se the difference. If you increase the development, you get sufficient contrast with an uncoated lens fir B&W. Color is a different set of issues.
Then again, coating 'flare monsters' like Plasmats and Cooke Convertibles made them far more useful.
On what formats do you find the 450mm Nikkor M usable for contact printing?
The 450mm Nikkor M is a great lens for 14X17, 12X20 and 16X20, if you stop down to f/22 or so. Also works for 20X24 if you stop down to f/64 or f/90, but the corners will be soft.
Originally Posted by Steve Hamley
I become a crossfield 656 drum scanner operator after seeing ansel dagor prints.
After 10 years of research and entering to internet age , I wrote to Zeiss Archives and asked what do they have in their hands about dagors. They sent two pages scan , prescriptions of Dagor 300 and 350 mm.
After looking , thinking about hundreds of lenses , you can see how dagor design is genius , rafinery and intelligent. At 350 , there are two symmetric group of glasses and a middle air section.
There is no air gap between each glass of these groups and it impress the observer.
I discussed the cooke xv design with cooke head designer and he sent me prescriptions and glass details.
It is now impossible to find every detail of these glasses for these lenses. It is lost.
May be I will buy them , disassemble and send them to analysis. Than copy with sol gel :)
Mustafa Umut Sarac
For you antique Dagor Fans, a catalog section of all the Goerz Dagor lenses as of 1904 here