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Reflection of secondary / corrector of Evo 8 EdgeHD in eyepiece

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#1 LessCloudsPlease

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Posted 27 July 2021 - 12:33 PM

Hi all,

 

Near the middle of the view (Evolution 8 EdgeHD) in my eyepiece (ES 92 12mm), there is an aberration visible, which looks a bit like a drop of water. All the details including screenshots are available in this topic, as I first linked it to the new eyepiece (but I'm lost on the cause by now):

 

https://www.cloudyni...condary-shadow/

 

Does anyone have an idea what this is?



#2 MisterDan

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Posted 27 July 2021 - 01:44 PM

If you have a Maksutov or other SCT (without the "EdgeHD" corrector), try the same experiment.  (The EHD corrector is mounted towards the rear of the scope, essentially coincident with the primary mirror, but within the primary baffle tube.)

 

If the "ghost" is not visible in another "non-Edge" cassegrain, using the ES 12mm, then it's likely an artifact "induced" by the interplay between the EdgeHD corrector and the eyepiece.  Any pair of "fortunately" (or unfortunately) spaced &/or curved lens surfaces in an optical group (or train) can generate a ghost image.  With the many elements involved (both scope and eyepiece), as well as the bright/daylight conditions, they may be more visible.

 

Best wishes and luck.

Dan




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