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Meade Polaris 90: selection of oculars


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#1 Andrey

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Posted 24 July 2018 - 02:43 AM

Greetings, dear Meade users!
 
  I want to achieve maximum magnification on my Meade Polaris 90, but without using Barlow lens.
  As far as I understood theory for this model:
  • Clear Aperture (mm) 90
  • Clear Aperture (") 3,5
  • Focal Length f/10 (mm) 900
  • Focal Ratio 10
  • Eyepiece(s) Three (3) 1.25" MA (26 mm, 9 mm & 6.3 mm)
  • Minimal Useful Magnification (CA/6) 15
  • Maximal Useful Magnification (CA*2) 180
 
  Therefore maximal useful magnification 180× is achieved with ocular 5 mm, which is just a not much smaller then that supplied 6.3 mm.
  However market offers oculars 4 mm that theoretically deliver magnification 225×, but it exceeds maximal useful magnification 180×.
 
  Do you suggest me to purchase a 4-mm ocular for this model of telescope?
  What optical artifacts can I experience with a 4-mm ocular?
 
  Thank you for a detailed reply.


#2 SBacon

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Posted 26 July 2018 - 05:42 AM

Hi Andrey,

 

Here's a link from Sky and Telescope that has a lot of valuable information concerning your question.

 

https://www.skyandte...-magnification/

 

Clear skies!

 

Steve



#3 SBacon

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Posted 26 July 2018 - 05:43 AM

Hi Andrey,

 

Here's a link from Sky and Telescope that has a lot of valuable information concerning your question.

 

https://www.skyandte...-magnification/

 

Clear skies!

 

Steve



#4 Andrey

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Posted 01 August 2018 - 01:27 AM

Dear Steve,

 

  Thank you --- I will read it and get back.






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