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Using a Recticle Finder EP for General Viewing

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#1 gustave

gustave

    Ranger 4

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Posted 23 February 2021 - 08:04 PM

What degree of compromise in general viewing is there when using  a crosshair reticle eyepiece with the LED illuminator crosshairs off?

TKs for reading...

 



#2 luxo II

luxo II

    Gemini

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Posted 23 February 2021 - 08:36 PM

Most reticle eyepieces AFAIK were typically Kellner, ortho, Plössl or Erfle types because the focal plane had to be accessible to install the reticle. Nothing particularly extreme and they should work OK in most scopes.

 

Those that are Erfle variants (SWA ones) have a curved focal plane that may be OK in a short refractor, but might not play nicely in a short Newtonian. The clue to these is to look carefully through the eyepiece and see if the reticle is all in focus at once. If it is, great. If it isn't, the focal plane is curved.

 

FWIW I have a 20mm SWA reticle eyepiece like this, its fine in a little 60mm finderscope but awful (Erfle) in an 8" f/5 newtonian. 


Edited by luxo II, 23 February 2021 - 08:38 PM.


#3 gustave

gustave

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Posted 23 February 2021 - 08:43 PM

Thanks for the concise answer Gemini!




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