Bausch & Lomb 240 aerial survey/photogrammetry zoom scope?

[PeteM]

I'm wondering if one of these B&L Stereozoom-derived microscopes could be used as a comparison microscope.we Here's an example, minus the stand, film handing, and light table that were part of the entire system:

https://www.ebay.com/itm/325889859488?

These look like B&L StereoZoom 4 pods, with the addition of two rotating knobs on the pod to bring two images into alignment and two "stereo rhomboid arms" attached below the pod. Those arms appear to be light pipes with a correcting lens at the ends to bring two separate images (aerial photos) up into the eyepieces. The original purpose, as I understand it, was to review stereo aerial images for photogrammetry purposes ranging from bomb targeting to cropland surveys.

My questions:

1) Is the B&L 240 pod, minus the arms, actually just a B&L SZ4 with the added image rotating feature for each eyepiece?

2) How much working distance is between the bottom of the arms and the specimen?

3) If two somewhat identical opaque objects were viewed and superimposed, would the effect be much like a comparison microscope (two flat superimposed views) or just mildly nauseating - like a stereo microscope misaligned?

Has anyone actually seen or used one of these? Or know where a user manual might be found?

[apochronaut]

The progenitors f the Z240 were the 70, 95 and Versatile. The 70 and 95 were named after the film fomats that they were mostly designed to accomodate and the versatile was a multi-fomat scope, also used as a comparison scope.. The 70 and 95 were direct modifications of a stereozoom but in order to limit image overlap with the Versatile, the optical tubes were made parallel, not convergent.This would be true of the Z240 and it's big brother the Z400 or 500....I think 500.
A prism system was used on the parallel models and later 70s snd 95s, I believe instead of a mirror porro due to space and used a dove prism, pechan prism and amici roof prism in sequence in order to get an even number of reflections and thus provide optical image rotation.

Prior to the development of the versatile , B & L offered a comparison system consisting of two Dynazooms under a g bridge, which could operate at up to 200X.
The Versatile and subsequent instruments apparently superceded that arrangement for comparison.

[PeteM]

Thanks, Phil. If I got that right, the 240 will have parallel rather than the convergent optics of a regular StereoZoom head - and thus might be OK as an epi comparison scope (assuming there's enough working distance under the rhomboid arms). Is that your thought? Or is it convergent optics, as with Greenough stereo microscopes and apparently the "Versatile" that would work best?

[apochronaut]

My understanding is that the Z240 is just a iater Versatile with more objectives available. The Versatile came out in the mid. 60's., the Z240 and the larger one ( I can not remember if it is a 400 or 500) were quite a bit later. All were used as comparison microscopes.

[Scarodactyl]

The 500 is neat. I got one cheap but it's so bulky and specific that I have not actually set it up. The higher mag objectives are also very short wd.