80/2.8 Xenotar in Compur #0

[Dan Fromm]

Went to a camera show today, came home $20 lighter and with an 80/2.8 Xenotar in a #0 Synchro Compur-P. The front element's front surface has the "cleaned with steel wool" look but it passes light and forms an image anyway.

Took a look at Schneider's age of lenses table to date it, was probably made around 1960.

Fine, good, but the oldest Xenotar document I found in Schneider's Archiv (http://www.schneiderkreuznach.com/archiv/archiv.htm) is dated 9/66 and says the lens goes in a #1. I have a set of 80/2.8 Planar cells of roughly the same vintage (early '60s) that fit a #1 too.

80/2.8 means a 27.6 mm entrance pupil. Since the #0's diaphragm opens only to 24 mm, the lens' front cell must magnify a bit.

The VM says a lot about f/2.8 Xenotars, doesn't mention shutter sizes. It has a picture of one on a board, not in a Rolleiflex, made in 1957, that looks like it is in a #0.

So, can anyone shed light on why old 80/2.8 Xenotars are in #0 and newer ones in #1? Redesign, other reasons, ... ?

Thanks,

Dan

[JG Motamedi]

Dan,

I have a feeling that in the early 1960s the Xenotar was redesigned. I base this on my experience with about ten different 150/2.8 Xenotars. I notice that the earliest one I have seen (and currently own), no. 4,120,xxx from ~1955 has a notably smaller rear element than the later 1960s and 1970s models. Importantly, this Xenotar also has the tea-colored stains of thorium glass in the rear element. All of the mid-1960s and later issues I have seen have been clear of the stain. An early (although I can't recall exactly how early) 135/3.5 Xenotar I owned also had the stain, although the later issues I have seen did not.

So, my feeling is that indeed, the Xenotar was redesigned sometime between its patent in 1954 and the early 1960s, replacing the thorium glass.

All that said, you can now tell me that your 80mm has no signs of the stain, and so my theory is shot, right?

[Dan Fromm]

Jason, thanks for the reply.

I looked, the thing's rear cell is water white. But and however, there could have been more than one redesign. And for all we know a previous owner bleached it with UV not too long ago.

Cheers,

Dan

[JG Motamedi]

Ah well. So much for my theory. Anyhow as you wrote, there well could have been several redesigns.