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A 5-3/4 inch diameter telescope objective

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#1 clamchip

clamchip

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Posted 13 March 2018 - 05:07 PM

I recently purchased this lens and thought with the odd diameter I would  find the maker pretty

quickly but no luck. Anyone have a guess?

its 5-3/4" diameter, coated on all four surfaces. If I place the elements with the arrows pointing at

each other R2 and R3 appear to have the same radii, and this would make R1 a slightly smaller

radius. R4 is flat.

If I have both arrows pointing at the sky it feels like R2 is touching the center of R3 because of

R2's smaller radius.

Its interesting the distinctly different glass colors of the flint (F) and the crown©.

It may be a Baker or a Littrow, or a Cook, or another design. I feel fairly positive it is a commercialy

made lens, and with the odd diameter what telescope is it from, or who made it?

I measured the focal length roughly 80-1/2 inches, and that makes it exactly f/14.

If I use 5-5/8" which would probably be the mounted clear aperture, it becomes f/14.3, providing

my rough focal length measurement truly is 80-1/2".

I thought the 5.75" x 80-1/2" might be metric and that would make the lens 146mm x 2045mm

Yes the black splotches are clam chips!

Robert

 

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Edited by actionhac, 13 March 2018 - 05:24 PM.

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#2 clamchip

clamchip

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Posted 13 March 2018 - 08:11 PM

Something I just thought of, I'll bet a bowl of clam chowder and a handful of saltines  R4 is optically

pretty flat and I can use it for a test flat! and it's in perfect condition, not a scratch, a few clams, but

no scratches!

 

Robert


  • wfj, terraclarke, rcwolpert and 1 other like this


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