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New Vixen SLV eyepiece


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Until my new eyepiece arrived, my two main eyepieces were the very inexpensive Svbony 9mm and 15mm Redlines, coupled with the Orion 2x shorty Barlow and the 3x trimag Barlow.  As a means of starting to upgrade, I recently bought the vixen LV 9 mm to compare to the Red Lion 9mm.

 

Ahead of a couple days of snow that was going to blanket our area and has, I went out this evening to view the waxing crescent moon hanging just above the trees in somewhat hazy skies. Other than the narrower field of view with the SLV and the field being noticeably brighter with the SLV, I could barely see any difference, particularly with field sharpness. I also did a run through star fields in Cassiopeia. Everything seemed to be just as comatic at the edge of the field of view in both eyepieces. I'm going to have to take more time and do some more rigid comparisons, particularly with clearer skies and a better-placed Moon, but as for the first batch of looks, it isn't promising. This was a quick test when I had time before I went to work that night and before everything clouded over. Shirley this $135 eyepiece has to be significantly better then that $25 eyepiece from Svbony but who knows. 

Celestron Omni 150, 6" f/5 Newt.

Edited by cpsTN
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I think if you did a head to head between those eyepieces in a scope with a slower focal ratio you would see a much bigger difference/improvement. The SLVs in my F/11 refractor are tac sharp, like orthoscopics but with 20mm of eye relief. An F/5 ratio scope such as yours is not too forgiving on eyepieces really, especially at the outer field edges.

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I've asked similar questions previously. To generalize - how can you determine, with a particular set of kit, the weakest link(s) in the optical train, and so be able to predict which upgrades might lead to a noticeable improvement in performance?

@Franklin's point makes sense - an F/5 newtonian inherently suffers from coma that affects the outer portions of the field, and that may "level down" the performance of different eyepieces. On the other hand, it's also said that faster scopes, with their more steeply converging light cones, pose more of a challenge for an eyepiece trying to minimize aberrations. By that reasoning, a fast scope may often reveal the better correction of a more expensive eyepiece. If the comparison is being done in a fast, high quality APO, you might expect to see any such differences in the resultant image quality. But in a fast newtonian, without a coma corrector, perhaps not.

I've seen enough comments about SLVs in the past to believe they are high quality pieces. Whether or not you will see any difference in a particular outfit ...?

I hope you get some more comments from people with more experience than me, I will be interested.

Edited by Zermelo
typo
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How about kidney beaning (SAEP)?  It should be fairly strong in the redline and nonexistent in the LV (or is it SLV, you use both in your post)?  I have the original 9mm Vixen LV, and it has much better stray light control and much less scatter than my cheaper eyepieces.  Try hunting for the E and F components of the Trapezium with each to see which shows them the best.

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My SLVs in my 250mm f4.8 Newt are razor sharp edge to edge. Image quality is close to the Orthoscopics I have.

I would think your image quality issues are elsewhere in the optical chain. You might want to check your collimation first to make sure you are getting the best out of your scope. Your primary or secondary may not be of good quality - the only way to check that is to compare scopes side by side. Have you done a comparison of eyepieces without the Barlow?

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The problem here is trying to compare eyepieces in "hazy" skies. The whole experiment is atmosphere limited and so no real comparison can be made. The field being brighter reveals that the SLV must have higher transmission, but why is the field bright? Because of light from the moon scattering in the atmosphere. Repeat the test in good clear skies and I am sure that the SLV will have a darker background sky with brighter objects because the coatings and baffling are far superior. Coma will be approximately the same in both eyepieces because it is primarily caused by the parabolic mirror of the telescope rather than the eyepiece. Astigmatism, field curvature and chromatic aberration are probably going to be the eyepiece aberrations to look for.

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