Repro Claron best aperture

[Matthew Cromer]

I have a repro-claron 305/9 in a Syncro Compur 1 shutter.

Anyone do tests with this lens or repro-clarons in general to determine the best aperture for shooting a subject at infinity with no movements?

I've read variously that this process-type lens is best wide open, and others claim that it has to be stopped down to f/22 to shoot infinity subjects or it will be unsharp (on 4x5??).

Anyone actually do tests of this versus relying on some dogma that process lenses have to be stopped down to f/22?

[Christopher Perez]

If you Repro-Claron is anything like other four element air space designs, it'll be quite sharp from f/9 thru f/32. These tend to be very stable optics from closeup work to infinity. Also note that at wider apertures you'll see the narrow DOF rather easily.

Many LF optical designs have been optimized for working distances of 1:5 thru 1:20 (depending upon manufacturer and product line). Many LF optical designs have also been optimized for work around f/22. Newer designs have tried to extend the "optimized" range up towards the wider apertures, and have tried to get all colors focused on the intended point (APO designs come to mind). But back in the day, Kodak tried to get as much resolution out of their Commercial Ektars as they could. So those lenses can be brilliantly sharp wide open (even though the tessar formula designs tend to drop resolution off center until at least f/11).

But your copy lens works rather well at a very wide range of apertures and working distances. It should be quite sharp through f/32 when photographing in 4x5 at just about any working distance. Shoot some film and see if you're pleased with the results. Schneider makes very nice lenses and I'm sure your Repro-Claron will be good.

[Diane Maher]

I use a 420 mm Repro-Claron on my 8x10 and I love it.

[David K.]

I read somewhere....I'm sure you can find it on the internet, that the Repro-Clarons had radio-active glass.

Not sure if that was just one focal length, or all Repro-Clarons. Aero-Ektars also had "hot" glass.
Just something to consider.

[Michael S. Briggs]

I've measured Repro-Clarons of several focal lengths, and they have all been radioactive. I think it likely that all Repro-Clarons include thorium glass.





A previous thread, with links to more: Repro-Claron VS G-Claron on 4x5 at http://www.largeformatphotography.info/lfforum/topic/498157.html.

[Diane Maher]

Well, I just had someone I work with check my Repro-Claron lens and it definitely set off the geiger counter. I found it interesting that the shutter didn't show any signs of radiation, so it must be contained only in the glass. It was both the front and rear elements. I also noticed a yellowish color to the glass which I'd never really noticed before and I've read that's also indicative of the radioactive glass. Oh well, I'll have to store this lens up and away from my film.