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Ole
03-28-2007, 10:32 AM
Alright - I know i'm supposed to be the "expert" on weird old lenses, but this one is just - too weird even for me:

It's a "Thomson Brothers, London" set with a barrel and five lens cells. The cells are only marked 1, 2, 3, 4, and 5. Cells no. 1 and 3 have a shiny brass ring that might indicate that they're supposed to be front cells.

Focal lengths are (assuming Fl in inches):

1: 20
2: 18
3: 18
4: 10
5: 14

Using cell 2 as a rear cell gives a very clear image with very good field flatness. Cell 4 gives a more curved image plane, also clearly visible without front cell. Cell 5 gives the most curved image plane I've ever seen, and no "mismounting" of any other lens cell I have is anywhere near as bad. To add to the conundrum cells 1-4 are two cemented elements, while no. 5 is a triplet...

I can only assume that this extreme field curvature was made on purpose, and the difference in the construction was done to make it even worse! So could this be made as a set for landscape and portrait work, where cell 5 was intended for portraits, 2 for landscapes, and 4 for more "general use" (and wider angle)?

Sellers pictures:

Ole
04-04-2007, 09:39 AM
Due to a rather surprising turn of events this casket set is going with me to Italy for one week. I'll return with lots of exposed 4x5" and 9x12cm negatives, so we'll see if it's any good. :)

I'm bringing a few other old lenses too: A Perken son & Rayment Portable Optimus (80mm), a Meyer Weitwinkel-Aristostigmat (12cm f:9),a Zeiss Doppel-Amatar (150mm f:6.8),a Goerz Dagor serie III 18cm f:6.8, and finally a Schneider Xenar 150mm f:4.5 - the only coated lens. Also the only one in shutter, the rest will depend on the focal plane shutter in the Speed Graphic! That's the main reason for bringing that one along - that, and the possibility that I might want som colour slides too.

With the casket set I get usable focal lengths from 80mm to 254mm in steps of 30 to 40mm. :)

glennfromwy
04-04-2007, 10:24 PM
Hey, Ole, that sounds like fun. I wish I was going with you, what with my collection of oddball lenses and Speed Graphics. We could take 'em by surprise. :)