Help me identify this please

[Gbealnz]

Gang,
I need a bit of help working out what this item is please.
It was with a large selection of filters etc.
Seems to "slip" over a 22mm opening ("about" 22mm).
There is a fixed lens on one end, with a square "iris" above that, in the middle. Then there is a small "eyepiece" in the top, a push-pull slip fit, with "2" on this eyepiece.
Any ideas?
Gary

 

[Robert Campbell]

A microscope eyepiece?

 

[Gbealnz]

Thank you Robert. Not sure what to say, could be I suppose, but why the "iris" inside. The eye lens gives a sharpish image of the iris.
Gary

 

[Robert Campbell]

That I don't know. It's really rather strange.

Microscopes don't (didn't) usually have interchangeable eyepieces. Telescopes do. It certainly looks like some sort of eyepiece.

 

[Shashin]

Whether it is a microscope or some other type of instrumentation is unclear. The "2" most likely refers to the system angular magnification. Having the rest of the instrument would give you the focal length of the eyepiece. Or simply try to project something outside your window and see where the real image would appear from the eyepiece on a piece of paper. You could calculate the focal length of the objective from there and it might give a clue. BTW, angular magnification on a telescope and microscope are not quite defined the same--telescopes assume infinity object distance, microscopes 10" object distance (if this was even based on any kind of standard).

The square is a bit of a mystery. Since it seems sharp though the eyepiece, then it is a field stop. It is adjustable and if the mechanism had some kind of scale then I would say it was a measuring eyepiece setup. But that does not seem to be the case. I have a measuring eyepiece from a micro-drill from an optics plant. Basically, the drill head had a microscope built in so the operator could see the work.

I am guessing this is pre-WWII. How "pre-" I am uncertain. I work with research microscopes. As far as biological or material scopes, this is not something I would expect to see on them. I would say it more likely comes from a tool like a drill or some kind of surveying/measuring instrument. But to be honest, that is a mystery.

 

[Shashin]

BTW, the "2" could simply be the number 2 eyepiece of a set or it could be a factor between that and the "1" of the set. If this was some kind of simple research setup where you would view a target with a know size to set the area, then use that scale to figure out or visualize scale on a sample, that is a possibility. But I am really guessing.

One thing is sure, it is not a toaster.

 

[Shashin]

Microscope, at least the research/scientific/medical variety, all had interchangeable eyepieces. I have a whole collection from different ages going back to (pre-)WWII to today. Measuring eyepieces and photo eyepieces have an etched reticle.

 

[Shashin]

BTW, measuring eyepieces are not used on modern research microscopes anymore. Much easier to measure right off an image or even to set a scale in the live view.