Are G Clarons usable as convertibles?

[Lachlan 717]

Specifically, I'm wondering whether a 355mm G Claron's rear element (only) will work as a free alternative to a longer FL lens.

Thanks in advance,

[Dan Fromm]

Lachlan, Schneider didn't design them to be convertible but there are convertible plasmats. Why don't you ask your lens what it can do for you?

[Lachlan 717]

Thanks, Dan.

I'll need to build some support arms for my camera before I'd subject it to this, so I was hoping for some (even) anecdotal evidence before I do this…

From what you wrote, it seems like it could be possible.

[Dan Fromm]

Lachlan, it will certainly work in the sense that a single plasmat element will pass light and form an image. You can confirm this by the traditional "project an image of a window on the opposite wall" test.

What isn't certain is how good the image will be.

[Lachlan 717]

Lachlan, it will certainly work in the sense that a single plasmat element will pass light and form an image. You can confirm this by the traditional "project an image of a window on the opposite wall" test.

What isn't certain is how good the image will be.

This was exactly what I had done!

I managed to put it on the camera and it easily covers the 7x17 field (rear element only). The view that I had is quite restricted, so infinity is hard to judge; however, with 750mm extension, a piece of 1/2" rope on a pole about 15 feet away was amazingly crisp on the GG.

Next time I'm out and about, I'll give it a go. Might give the 240mm Computar a crack as well. That would fill the lens range nicely, for those rare times I want something other than wide - 240mm, 355mm, 480mm and 760mm.

[imagedowser]

Have not tried my late G Claron 355 yet but my early (10 xxx xxx) 305 'Goerz type' G Claron seems to work fine on the gg at f16... Couldn't put my hands on the extension for the 8x10 so I used the front glass on the lens instead of the rear, to get it to focus... it's getting dark here, so I'll give it another go with both lenses and full extension in the morning.

[imagedowser]

Yes, on the older 305 and yes, on the newer 355 (14 xxx xxx), using the rear elements on both, focusing wide open. Focal length was 24 1/2 and 27 1/2(ish) I have to say, the 305 seemed to give better sharpness on the gg, but you would have to shoot and print to really know how much.... Jim Galli, made a casket set out of older G Clarons so if you could find older lenses in, say 240, 270 and 305, you could mix elements for many focal lengths as Jim did.... The obvious next question is, could you do that with the plasmat type lenses? I have a 240 plasmat but nothing in a 210 to 305 to match it with... Anyone wanna try?

[Wayne]

So is the newer G-Claron 305 (which I have) supposedly not "convertible"? I tried pulling the front element and it seems to focus at about, or slightly beyond, how far I feel comfortable racking out my Ansco 8x10's bellows. I've got an extender around here somewhere that might make it usable.

[Jan Becket]

Yes, the newer G Clarons all work well as convertibles, but only for B&W. I used my 150 regularly as a 300 and got tack-sharp results which sometimes looked better than with the lens in the 150 configuration. To double the focal length, remove the front element and replace it with a medium yellow filter. I forget which size fits the Copal 1 —maybe 34.5 mm. The filter is necessary to correct a problem with the focus of some parts of the color spectrum. The G Claron is only single-coated, so a lens hood is mandatory, but hard to attach with the lens in the 300 mode.

[Lachlan 717]

Yes, the newer G Clarons all work well as convertibles, but only for B&W. I used my 150 regularly as a 300 and got tack-sharp results which sometimes looked better than with the lens in the 150 configuration. To double the focal length, remove the front element and replace it with a medium yellow filter. I forget which size fits the Copal 1 —maybe 34.5 mm. The filter is necessary to correct a problem with the focus of some parts of the color spectrum. The G Claron is only single-coated, so a lens hood is mandatory, but hard to attach with the lens in the 300 mode.

Thanks, Jan.

I'll give it a crack!

[David Schaller]

I would be very interested to know exactly what size yellow filter would screw into a Copal 1 shutter, when the front element is removed. I have had to just hold a larger filter up in front of the shutter during exposure--not very convenient.
Thanks,
Dave

[Ian Greenhalgh]

I don't think there is a filter with the right diameter and thread pitch. A 40.5mm filter is just and so too small in diameter and has a finer thread.

[Paul Ewins]

The front thread of a #1 is M40x0.75 while a #3 is M58x.75. The thread pitch on a 58mm filter is correct but the one I tried wasn't long enough to engage with the thread on a Copal 3 which starts a few mm below the lip.

[David Schaller]

Thanks, I was coming to the same conclusion from a quick look around the web. Sad though; it would certainly be nice to use convertible lenses, or ones that can be converted, with the convenience of a dedicated yellow filter.

[Keith Fleming]

I have two Zeiss Protar VII cells mounted in a Wallensak Alphax shutter. The shutter threads are 45mm, but as Paul experienced on his shutter, a 45 mm to 52 mm adapter would not screw in deep enough to fully engage the threads. S. K. Grimes made me an adapter with deeper threads, so I can use the two cells individually and have a 52 mm filter and extra Nikon lens hood on the front.

I am planning on having Grimes make me a second adapter of the same size. That would allow me to use a 52 mm Nikon close-up filter on the back of the shutter and still have the yellow filter and lens hood on the front of the Alphax. The close-up filter used in this way acts as a long-focus meniscus lens--and the shutter will allow me to vary the amount of softness on the film.

Hope this helps.

Keith

[Wayne]

Yes, the newer G Clarons all work well as convertibles

Thank you. Every reference I was able to find always specified "older G-Clarons" could be used as convertible lenses, but none came out and said newer one do not.