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Old 23-02-2021, 08:59 PM
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gregbradley
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Join Date: Feb 2006
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Quote:
Originally Posted by Don Pensack View Post
If it's a high-end Barlow, like a Baader VIP or TeleVue powerMate, there is no difference in performance between the higher power eyepiece and the Barlowed lower power eyepiece in general.
Except:
--the higher power eyepiece without a Barlow will be a lot lighter and put less stress on the focuser.
--the lower power eyepiece with a Barlow may, in some circumstances, show more light scatter or internal reflection. That depends a lot on the Barlow.
--the combination of Barlow and Eyepiece might be difficult for users of coma correctors. That stack can get very long and heavy.
--a lower power eyepiece that has induced astigmatism from fielding a short fat light cone might have less astigmatism when used in a Barlow.

I would also comment that my lifetime-best view of Jupiter was with a PowerMate (4 elements) + Paracorr (5 elements) + 8mm Ethos (9 elements). It looked like a Christopher Go or Damian Peach image, only sharper. Full technicolor, too. No more light scatter than I saw in the eyepiece by itself. Different colors on each moon, and albedo features on Ganymede. The keys: great optics and stunningly perfect seeing. Lens count? Not very important, it seems, at least with optics of that quality.
Thanks Don.

I did some dark site viewing a few nights ago and tried the barlow out and I came to the same conclusion.

A decent barlow is a good accessory.

Greg.
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