Eyepiece w. the smallest magn. for the self-made stereo mic

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enricosavazzi
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Joined: Sat Nov 21, 2009 2:41 pm
Location: Västerås, Sweden
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Post by enricosavazzi »

Some preliminary results with add-on lenses held by hand directly in contact with the front of Pentax Papilio 6.5x21 binoculars.

These binoculars have a minimum focusing distance of 0.5m and are designed for close-focus observation. The objectives approach each other sideways at close focus (only 7 mm distance between the clear inner edges of the objectives), which reduces vignetting with an add-on lens. The outer clear edges of the objectives remain about 52 mm away from each other at closest focus.

Sigma Life-Size Attachment, 52 mm thread diameter (but a clear diameter of only 35 mm):
Binoculars focused at infinity: about 38 mm wide FOV. Difficult to superpose the two images into a single one. Apparently the outside periphery of each image is strongly vignetted by the add-on lens.
Binoculars focused at 0.5m: about 25 mm wide FOV. Much better image, much easier on the eyes.

Raynox M-250 (clear diameter 34 mm):
Binoculars focused at infinity: about 16 mm wide FOV. Same problems as with the preceding lens with binoculars focused at infinity.
Binoculars focused at 0.5m: about 10.5 mm wide FOV. Much better image, much easier on the eyes.

This suggests that, even with these binoculars that have objectives very close to each other, one needs a CMO lens with clear diameter of 52 mm or more with the binoculars focused at closest distance, or at least 60 mm with the binoculars focused at infinity. I believe I have a 2-3 element 58 mm Canon add-on lens which might be worth testing, but unfortunately cannot find it.
--ES

dolmadis
Posts: 899
Joined: Wed Dec 07, 2011 1:51 pm
Location: UK

Post by dolmadis »

Thanks Enrico.

I think that I have a 60mm add on lens for a Lomo CMO somewhere.

Did not benefit as I had hoped so this might be a better use.

BR


John

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