To anyone who has the answer:

I have a Rodenstock ronar 300mm f/9 process lens, and want to use it on an enlarger. Can anyone tell me what's the difference between a process lens and an enlarger lens. Since Rodenstock produces both enlarger lenses and process lenses. I am confused by these two different catagories. Thanks.

Howard

-- How-foo Chen (howfoo@seas.ucla.edu), April 05, 2001

Answers

There's only a slight difference in the requirements for process and enlarging lenses. Enlarging lenses are ususally optimised for 1:5 conjugates, or thereabouts, and process lenses are usually optimised at 1:1 or 1:2.
. In practise and at 300mm focal length, I doubt you'll see any difference between the Ronar and a similar enlarging lens. The Ronar is an old design, so you can't expect the ultimate in performance from it. The Apo-Ronar is much better.
It used to be reckoned that enlarging lenses were made 'tougher', to withstand the heat of the lamp, but I've seen the coating burned off the back of an El-Nikkor from lengthy exposure to a high intensity lamp, so that's probably an old wives tale.

-- Pete Andrews (p.l.andrews@bham.ac.uk), April 06, 2001.

Well, while Bob is not listening, we could add that an enlarger lens is more luminous (4-5,6 instead of f-9) which can be precious for both focus control and not to prolonge the exposure times beyond the point where reciprocity failure manifests, has somtimes a lit f-stop scale and is made in different versions best optimized for certain enlarging values.

-- Paul Schilliger (pschilliger@smile.ch), April 06, 2001.

Great question. I'm also interested in distinctions, since I've been thinking about lenses to enlarge 8x10.

Looking at Schneider's webpage, and consistent with Mr. Andrews' response, I noted the following.

Process lenses (e.g. G-Claron, Macro-Symmar) are optimized for 1:1, with the ability to enlarge in either direction: 4:1 to 1:4. They're symmetric, to the extent that the front element is the same size as the rear element. So, they can magnify as well as reduce.

Enlarger lenses (e.g. Componon-S) appear to have front elements that are larger than rear elements. Does this imply that they're intended to magnify versus reduce? Typically, we don't often make the print smaller than the negative, do we. There's also a difference in the mechanical mounting, to make the lens more convenient for enlarging. (e.g. illuminated f-stops on smaller lenses, etc.)

I wonder how the two compare for contrast?

Just some observations.

-- neil poulsen (neil.fg@att.net), April 06, 2001.