Old brass lens question

[rjphil]

Hi All -
I was recently given an 8x10 camera that was originally used by a local studio back probably in the 30s and 40s. With it came a 9.5" Goerz-Dagor, and a small brass lens that I am unfamiliar with. It is inscribed "R.D. Gray, New York Extreme Angle Periscope No.4". It has a thumbwheel for the aperture, with stops from f/16 to f/56, and no shutter. Any information would be helpful. I'm going to try it out this weekend, as it is on a lensboard. Thanks very much!

[Toyon]

A periscopic lens is a symmetrical lens, consisting of two equal periscopic convex lens elements and the aperture between the elements (Wikipedia). It is possibly a wide angle aplanat type, or similar. I don't know about your lens, but well-constructed aplanat wide angles can be superb lenses. Most like it was produced by one of the major lens makers for the retailer, R.D. Gray - a common practice in those days.

[Steven Tribe]

The no. 4 (for 8x10) suggests a Continental origin. If the focal length is around 176mm, then this might be the Steinheil objective sold under another name. It is described as never being very sharp in focus and it is necessary to amend the bellows focussing (ground glass image) before exposure as there is difference between the visual and actinic focussing planes.

[rjphil]

Thanks! I'll see what I get this weekend.

[Ole Tjugen]

... It is described as never being very sharp in focus and it is necessary to amend the bellows focussing (ground glass image) before exposure as there is difference between the visual and actinic focussing planes.

The difference in visual and "actinic" focal plane was due to the insensitivity of "colour blind" plates to green and yellow light which is what the human eye sees sharpest. With a panchromatic emulsion there is no focus shift.

That being said, a yellow filter works wonders on these lenses.

[Neil Purling]

It sounds like a wide-angle rectilinear. For 8x10 focus would be 6". Coverage is massive at the expense of speed & focusing is a pig to do on a dull day. I know, I mounted a 6" f16 Wray W.A.R. onto a lens panel for my Pacemaker Crown Graphic.

[Steven Tribe]

You can very easily confirm if it is the periscope design as these have two simple symmetrical crown glass lenses at each end - you can check the number of reflections. Unlike many other terms, "periscope" on a lens usually does mean what it implies. Steinheil's wide angle periscope was up to 110 degrees which accounts for its success at a time when WAR were already available.

With old blue sensitive only b&w films, it was suggested that the film plane should be moved 1/40 of the ground glass focussing distance. By restricting the range of colours passing through the lens, as Ole suggests, the "smearing" of the out-of focus colours will be reduced on the b&w film.

[CCHarrison]

See attached ad for your lens

Dan

[Steven Tribe]

Here is another Gray catalogue with both the normal and EWA periscope.

The rear lens can be used alone as a landscape lens.

The wide angle - 115 deg - gets me to think that this might be based on Busch's Lux Artium - which perhaps deserves a mention as another soft lens type.

There was a discussion on this objective on photo.net in March 2008.