Coma Corrector Vs. Barlow

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Refractordude
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Coma Corrector Vs. Barlow

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Post by Refractordude »


A barlow lens will increase the focal ratio of a telescope. So can a barlow lens replace the need for a coma corrector? It is my understanding that a coma corrector is used for low focal ratio reflectors. Thanks all
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notFritzArgelander
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Re: Coma Corrector Vs. Barlow

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Post by notFritzArgelander »


Refractordude wrote: Wed Oct 06, 2021 12:23 am A barlow lens will increase the focal ratio of a telescope. So can a barlow lens replace the need for a coma corrector? It is my understanding that a coma corrector is used for low focal ratio reflectors. Thanks all
No. Let's say you have 2 eyepieces, 15mm and 30mm, and a 2x barlow. Let's say you see coma looking through the 15mm eyepiece. Put in the barlow and double the magnification. You'll then see the same coma in the 30mm eyepiece that you saw before in the 15mm at the same magnification.

The coma corrector eliminates the coma at the focal plane of the scope. The barlow just magnifies whatever is at the focal plane. That's the key. What is the image like before looking at it with eyepiece and maybe a barlow?
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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