Rodenstock

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Does anyone have any documentation on the optimum f-stop for a Rodagon 80/4 enlarger lens?

John

-- John (jreefjreef@yahoo.com), January 24, 2002

Answers

Just to get the ball rolling: This is the lens I use for enlarging 35mm and 6x6. I always use it at f8 where it seems to work very well (although noticably less well than a leica focotar 2 (f4) that I borrowed (allegedly the sharpest ever e.l. for 35mm)). Come to think of it that's probably not that much help...

-- steve (stephenjjones@btopenworld.com), January 24, 2002.

I suggest that you examine the grain of a negative through a good grain magnifier while you stop the lens down. Typically the grain will get crisper for the first few half-stops down from wide open and then begin to get mushy again from diffraction as you continue to stop down. I have done this and found that the best stop on my Schneider Componon-S 80/4 is f/6.3. I'll bet it's very close to that on your Rodagon.

-- James Meckley (jmeckley@pegasus.cc.uccf.edu), January 24, 2002.

The sharpest aperture ought to be f/4.
I was provoked into doing some tests on my 50mm f/2.8 Componon-S recently, and I was very surprised to find that the central resolution was close to the theoretical diffraction limit. The resolution actually reduced as the aperture was closed down from maximum, but obviously, other factors like depth-of-focus made the end result more acceptable a couple of stops down.

From this experiience, I'd hazard that your best aperture will be particular to your own enlarger, lens, and magnification; and that you'll have to find it by trial and error.
Sorry if this doesn't sound very helpful

-- Pete Andrews (p.l.andrews@bham.ac.uk), January 25, 2002.


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