View Full Version : 12" Dagor Quality/Coverage on 7x17
I recently mounted a 12-inch Goerz Dagor, Series III/ f 6.8/ No. 6 in shutter to a board I had fabricated for my Folmer/ Schwing 7x17. I am ready to go (despite needing to have my lone filmholder re-worked).
I would appreciate anyone (preferably with direct experience) giving me some feedback on the following questions I have. Many thanks!!!
1. Despite no coating on my circa 1918 specimen, is it true that the lens' simplicity of design with its fewer air to glass surfaces will still give me decent contrast?
2. Ron Wisner said the lens had around an 89-90 degree angle of view. That seems a bit tight for the 19-inch diagonal of the 7x17 format. Will stopping down to around, say, f 22, give me a decent amount of useable image area, let me avoid vignetting, and give me some wiggle room?
3. I am aware that this particular lens is commonly used on this format. But what might be another step up in similar focal length? What about a 305 G-Claron? Differences, simularities?
Would the longer 355 Claron necessarily be a whole lot better by virtue of it's increased coverage? I know this is subjective, but I'm curious about other's preferences and why.
I know I need to field test myself. But I like to get it in the head first. Sorry.
Many Thanks In Advance Amigos,
Robert McClure - Atlanta
(1) Yes, you will have very nice contrast. The Dagor design consists of just two pairs of cemented triplets set symmetrically around a stop. This makes for four air-glass interfaces amd four cemented interfaces. Coatings obviously reduce flare, but with a design as simple as this, you will have very useable results from uncoated lenses also. Once you get into plasmats and dialyte designs, single coatings do help. Multi-coatings made it possible to produce the multi-group zoom lenses for smaller formats. Their benefits to the simpelr designs of LF optics are smaller.
(2) The 90 degree coverage figure is at small stops (i.e., f/45). But Dagor coverages do vary a bit depending on vintage. In any case, the 7x17 format needs about 19" to be covered and the 12" Dagor should be able to give you about 22" of image circle. You might need to stop down to get the corners sharp enough but it should work.
(3) The Dagors are, in my opinion, fine lenses. Assuming the lens works fine for you, you might be better served by spending your money on film. But if you find yourself restless, some options to consider are the G-Claron, the Computar, the Kowa-graphics.
RE DJ's comment #2: keep your eyes peeled for an f/7.7 version of the 12-inch. Better coverage.
Hi Robert. 7X17 huh? I have used my 12" Dagor on my 12X20 successfully. Pretty tight squeeze but it covered. So 717 will be easy for it. 12" = 305mm. Don't know that the G-Claron has any more coverage but they are very sharp. Most Dagor's are no slouch either. Since you'll be contact printing and diffraction isn't an issue I'd plan on almost any exposure at f64. It will even things out very nicely across 7X17. My guess is you'll be very pleased. A 355 G-Claron is a handsome lens on 717 and you'd break the camera trying to find the edge. If you feel you'd enjoy super-wide, (the 12" is already wide) wait for a series IV or V Protar that says it covers 10X12. The V is 8 3/8" and will cover easily, and the IV is 10 1/4" and would also cover easily. Hope you're having fun with that antique. Longer than 355 will tax your bellows and you'll run out of camera bed by 420mm or so. Good luck. Jim
"RE DJ's comment #2: keep your eyes peeled for an f/7.7 version of the 12-inch. Better coverage."
Is there really such a thing as a 12" f/7.7 Dagor? I have never heard of one. Most regular Dagors were made with a maximum aperture of f/6.8 in focal lengths up to 12", and with an aperture of f/7.7 for 14" and longer focal lengths. There were f/9 Dagors that did offer slightly better coverage than the regular Dagors, but these were wide angle lenses with a different design.
Thanks guys for your great reactions/responses. Ya know, it's not like folks who do this/understand this grow on trees, mind you.
DJ: I appreciate your helpful, thorough, and informative responses. All so encouraging. (I encourage people for a living but have grown used to receiving little of it myself.)
Chad Jarvis: Thanks for a heads-up. I do look forward to combing the used market for my next lens acquisition.
Jim Galli: You were very informative and helpful. Thanks! Between its increased sharpness (over the Dagor) and slightly longer focal length, I'm champing at the bit to see how the 355 Claron reveals the world. The FS you sold me on Ebay is the ideal compromise - to have 7x17 capability but not have to declare personal bankruptcy. It's worlds better in terms of construction than the corresponding Korona, too. Yes, I look forward to getting my hands on a Protar, as you mention. Unfortunately, my current ready cash is tied up - in debts.
("Professor") Sandy King: Your remarks were also interesting. You won't remember it, but you had sold me over the telephone (around 4 years ago) an original Invisible Mfg. Co./Korona 7x17 holder. I had told you I needed something to dimension my planned DIY 7x17 around. The holder has perpetuated my self-education and will soon be pressed into service. (You may or may not recall that you had once told me during a call to you that you were soon off to the Southwest to photograph some sort of ancient Indian Cave Dweller paintings or something like that. I was tortured!)
Robert McClure - Atlanta
I remember our phone conversations very well and am pleased that you will finally be able to put the 7X17 holder to use.
As for the 12" Dagor, I agree with other posts that suggest that this will be a very good lens for 7X17. It should cover this format with two or three inches of movement when stopped down to f/32 and more. Dagors only have four air-to-glass surfaces and are by nature very contrasty, even very old uncoated specimens.
Powered by vBulletin® Version 4.2.0 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.