Two weeks ago I bought a 300 mm (12 inches) telephoto lens for my Toyo 4x5. The lens is in E++ condition and it seemed a good buy at the time.

The lens is an "older" C.P.Goerz-Berlin-DAGOR, F: 6.8, No. 659021 (not a DAGOR Red Dot). The lens is mounted in a COPAL No. 3 shutter which is in absolute immaculate condition. The following are other specs.:

Max. ap: 6.8 Min. ap: 64 Spd: T and B, 1 to 125

Now, the big problem is that I can not get any contrast (black and white) with this lens. I have other lenses who behave more properly and given the same shot perform perfectly.

This lens has me confused - and I need to clear my mind. I have upped the aperture up to 6 times and closed down up to 2 times and all the shots look basically the same...a very dull gray. In the zone system all these shots will be around zone 5 or 6.

Does anybody have any idea about what is going on? Please don't tell me to use this monster glass piece as a paper weight...it will one of the most expensive I have ever seen.

Thanks - John the Fisheye

-- C. John Nemaric (foto64@yahoo.com), February 22, 1998

Answers

I'm not familiar with this lens, but I would hazard a guess that it covers a much larger area than 4x5? Focus on a bright scene then remove the ground glass. See what the off-axis light is hitting. Could be a flare problem. You may need to intentionally limit the lens coverage with a hood.

-- Tim Brown (brownt@ase.com), February 23, 1998.

Have you checked it for flare? Focus the camera plus lens on, say, a lit torch in a coal cellar. The negative should, of course, show a black dot on an otherwise clear negative. If your "good" lenses do this, but this one fogs the rest of the image, then flare is probably the cause (but the cause of the flare might, of course, be a mis-alligned element, which might show up by focusing the camera on a brick wall).

I use some old Leica lenses that "suffer" from flare. Increased development compensates for the loss in contrast, and the results can be rather magical.

-- Alan Gibson (gibson.al@mail.dec.com), February 23, 1998.

I agree with the previous posts as concerns flare being the most likely cause of your problem. Just a couple of other thoughts, were you making the exposure into the sun, or was the sun on the front element. If this is an uncoated, or single coated lens that would induce flare. Also, what kind of board is it on. is the back of the board black, and does it fit properly. I would verify that the shutter is in proper order also, I can't imagine it would cause a flare like problem, but stranger things have happened.

-- MTHOMPSON (MTHOMPSON@CLINTON.NET), February 23, 1998.