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jackpie
29-Jan-2014, 18:54
I've collected a number of G-Claron lenses and it's been suggested to me that the elements could be interchanged and used as a casket set. So using the 210, 240 and 305s that fit into a copal 1 what focal lengths could be made? what adjustments to the aperture scales would be necessary for correct exposure? and would there be compromises in the lens performance?

Andrew
30-Jan-2014, 13:52
http://www.largeformatphotography.info/forum/showthread.php?63200-A-discovery-Dagor-type-G-Claron-s-as-the-ultimate-Casket-Set

as much as I know...

Dan Fromm
30-Jan-2014, 14:26
If, and this is a big if, dagor type G-Clarons follow the f/6.8 Boyer Beryl pattern, half of a 210/9 will be a 360/18; 240, 410; 305, 522. Combining unlike cells won't buy you much, 210 + 240 = something in between, and so on.

Kirk Fry
30-Jan-2014, 19:32
So what happens if you just use half a G-Claron? Anyone try that? Then you get a whole bunch of interesting focal lengths. (710 mm etc.)

Dan Fromm
30-Jan-2014, 20:28
Kirk, I just put the question to a 210/6.8 Beryl and a 210/9 dagor type G-Claron. I measured with very low precision and accuracy. They're about the same. A single cell's focal length is around 1.7x the complete lens' focal length.

By the way, plasmat type lenses are convertible too. Well, not that many, according to their makers, but single cells will form an image. A single cell's f/# is usually twice the complete lens', its focal length is around 1.7x (convertible Symmars, 1.75x) the complete lens'.

Don't be pikers, if you're going to play silly lens games with dagor types, play them with plasmat types too.

Jim Galli
31-Jan-2014, 10:06
I have one by accident. Years ago a seller on ebay very apologetically offered a 210 rear and 240 front old style dagor type for cheap and knowing that Schneider had done that same thing years ago with the original dagor type Symmar's I thought, why not? It's a killer performer. 225mm. Covers 8X10 very nicely, and seems perhaps sharper than the others (probably just my over-active imagination). I saw no need to experiment further. A 270 and a 210 would make a 240 with smaller than standard full aperture. I've already got a 240. Who needs that. I suppose a 270 front and 240 back would make a viable 255, but ??? Not worth the trouble. the jumps are too small to bother with.

Whatever you do, put the larger light in front, smaller one in back.