Telebinocular viewer

[P3D Peter Abrahams <telscope@xxxxxxxxxx> To: photo-3d@xxxxxxxxxxxxxxx]

I also have a No. 46 Telebinocular viewer and am excessively fond of it, and in fact it was the first stereoscopic device I acquired, so it got me started towards this Black Hole of Calcutta. Mine came with a 1964, 26 page manual, that describes its use in screening individuals for stereoscopic ability.
Included are a dozen photo cards used for this purpose, which I have augmented with cards used to test children. I believe this one was used by the Forest Service to test applicants for training in mapping using aerial photos.
The manual refers to 'the old No. 38 Telebinocular', as well as a Televiewer. The No. 46 is covered by patent 2,557,608. Do any readers have ready access to patent information, to check if that patent relates to the oculars? 

Regarding the use of single element objectives in Holmes or other viewers, one can make do with it because the magnification is very low, minimizing but not eliminating chromatic aberrations. Doublets correct other aberrations in addition to color, greatly improving edge of the field performance.

The newly created viewers under discussion are made with lenses sawn in half and transposed. Why not use two whole lenses, and mask the 'converging' (outer) half?

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Peter Abrahams telscope@xxxxxxxxxx
the history of the telescope, the microscope, 
and the prism binocular


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