Edmund RKE a classic or outdated?

Discuss telescope eyepieces.
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WilliamPaolini United States of America
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Re: Edmund RKE a classic or outdated?

#21

Post by WilliamPaolini »


Hi Don. Yes I noticed that some of the Morpheus line (that was one of their design parameters I understand) and the 35mm Ultrascopic both have that character, although not as well as the Edmund 1-1/8" shows it. But the Nagler 3-6 Zoom has only 10mm ER. I had that one, as well as the 2-4 and with that tight ER the effect was definitely not there at all for me. Compared to me, YMOV (Your Mileage Obviously Varies) :-)
-Bill

U.S.A.F. Veteran - Visual Amateur Astronomer since 1966 - Fully Retired since 2019
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Pentax XWs - Baader Morpheus - Takahashi LEs - Edmund RKEs - BST Starguiders - 6ZAO-II/5XO/4Abbe
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Don Pensack United States of America
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Re: Edmund RKE a classic or outdated?

#22

Post by Don Pensack »


The Nagler 3-6 zoom has an eye lens that is only about 1/3 as large as the top of the eyepiece.
But by the time you get to the exit pupil of the eyepiece, your eye's perspective of the wide black area surrounding the lens narrows down to just a thin black line around the field.
Pull back from the eyepiece because you are uncomfortable only 10mm away from the glass, and the thin black line around the field becomes wide and thick again.
The black line around the field does not completely disappear, but then it doesn't completely disappear on the RKE either, it just appears to be very thin.
It's a type of foreshortening, though not that used in art.

I only referred to the Zoom to point out that an eyepiece doesn't have to have a lot of eye relief, or a large eye lens, to display this characteristic.
It merely has to have a perspective, from the exit pupil, of the top of the eyepiece that makes little of the aluminum barrel outside the eye lens visible to the eye from that position.
Astronomer since 1963
Currently using a 12.5" dob and a 4" apo refractor
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