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View Full Version : Scale for 13" f6.8 Conley triple convertible lens

DrTang
5-Feb-2017, 14:29
I have the above lens..in shutter, however the aperture scale is only for the 13" size

if someone has such a lens with the triple convertible scale, and could send me a photo of the scale so I could estimate where to set it for the other two lens sizes (20" with rear element only and 25 1/2" with front only)

I would be in great debt

pjd
5-Feb-2017, 21:42
An alternative (if nobody steps forward with an image of the correct scale) is to create a scale in mm and calculate directly.

For example, I think the wide open aperture should be 48.5mm in diameter (13" or 330mm / 6.8). If that's wrong please disregard the following!

If that calculation proves correct, a 25" cell (635mm) would be f13 at the wide open aperture. A 20" cell (508mm) would be about f10.5 wide open.

This sort of calculation has worked for me, and I quite like using mm scales on a lens, measuring actual focal length and dividing by aperture in mm incorporates bellows extension factor too, when that's an issue.

Keith Fleming
6-Feb-2017, 23:36
If I remember correctly, the Conley line was made up of re-branded (by Sears Roebuck) Wollensak lenses. The 13-inch focal length raises the possibility that this lens is a rebranded Wolly Series 1. If I am right, owners of that Wolly lens may be able to answer your question.

Keith

DrTang
7-Feb-2017, 07:58
If I remember correctly, the Conley line was made up of re-branded (by Sears Roebuck) Wollensak lenses. The 13-inch focal length raises the possibility that this lens is a rebranded Wolly Series 1. If I am right, owners of that Wolly lens may be able to answer your question.

Keith

Thanks!

desertrat
8-Feb-2017, 13:15
I have two Wolly series I lenses for 8X10, but one was missing its aperture scale and the other has only a single scale. It's interesting your lens is an f6.8, as that would make it a very early one. I have one of those also, and it is a symmetrical lens in that both cells have the same focal length. If yours is a triple and f6.8, it might possibly be a different design.

The series I is a continuation of the Royal Anastigmat by the Rochester Lens Company, which Wollensak purchased in 1905. In 1908 Wollensak changed the name of the Royal Anastigmat to Velostigmat Series I. It is an unusual lens in that each cell contains two cemented doublets separated by a spacer. It might be interesting to count reflections of each cell individually illuminated by a single small light source. If the Conley lens is a Wolly series I, you should see 4 bright and 2 dim reflections in each cell. If the reflection count is different, the lens would be a different design.

I might be able to help with the aperture scale. I have a Gundlach Turner Reich triple with nearly the same individual focal lengths as your Conley. My cells are marked, 12", 19.7", and 25". The combined focal length with both cells is actually closer to 13". Maybe one of our lens gurus could tell us if the aperture scale would be fairly close to what you need, even though the lens is a different design. I'm thinking the aperture error would be fairly small, and might have less effect on exposures than variations in shutter speeds from the marked values, which might be considerable.

Anyway, if the Turner Reich aperture scale would be useful to you, I could try to get a close-up image of the scale and post it here.

DrTang
8-Feb-2017, 13:43
that would help a lot

it doesn't have to be super accurate..I'm shoot B&W neg and ..'in the neighborhood' would be cool... I'm just guessing right now and half the time I forget anyway..so
... anything is better than that

desertrat
8-Feb-2017, 16:05
DrTang, here is the aperture scale of the Turner Reich Triple.

The outer scale is both cells combined, the middle scale is the 19.7" cell, and the inner scale is the 25" cell. The inscription furthest to the right on each scale is the focal length of that scale.

Hope this helps.
160999

DrTang
8-Feb-2017, 18:04
Super Excellent - that is close enough so I can make a chart for the studio

thank you so much

M.

DrTang, here is the aperture scale of the Turner Reich Triple.

The outer scale is both cells combined, the middle scale is the 19.7" cell, and the inner scale is the 25" cell. The inscription furthest to the right on each scale is the focal length of that scale.

Hope this helps.
160999