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2" Eyepiece Recommedation for AT72

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#1 meteorite


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Posted 19 January 2013 - 06:17 AM

Hello Everyone,

I will be receiving an AT72 refractor next week and I would like some recommendations for a 2 inch eyepiece. Here are the specs on the scope (and myself).

I am 51 years old, been in Astronomy for about 40 years, give or take. I am assuming my eyes dilate to around 5 mm. Floaters? Yep. Don't know if it matters but I am very myopic (-10 left eye and -8 right eye) with some astigmatism. Sometimes I observe with glasses; sometimes without. Sometimes with contacts.

The AT72 is, of oourse, 72mm aperture with a Fl of 430mm. I will be using an Orion 2 inch 99% dieletric diagonal.

Price range? Undecided.

Recommendations and comments appreciated.





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Posted 19 January 2013 - 07:34 AM

Hi Walt, I love the AT72ED. It was the first Scope I ever bought. Every EP I buy gets its first light on this scope; so convenient to use and takes up so little space. I can just sit it on the window sill and do some scanning of the woods across the way in my backyard.

A 72mm scope with a 5mm exit pupil requires a magnification of 14.4x. The resulting Focal Length(s) are 430mm for the scope and 29.9mm for the EP; assuming my math is right. So, the lowest you can go is theoretically 30mm. While every low power EP looks good through this scope :-) I prefer the wide field EP's to spread the image across a wider AFOV; in daylight there is just too much detail for a narrow AFOV from a Plossl. Assuming you are going to purchase a EP for this scope you can go as low as a 68 degree 30mm GSO SuperWide for $89 and till get good images. If you want a Plossl then the Smart Astronomy 30mm Sterling Plossl for $79 is an excellent choice as well. If those two aren't your cup of tea, you can certainly go the other direction and spend ~500 and get a high end TV or Pentax for instance.

As I said, anything goes with this scope; the sky's the limit; literally! :-)

#3 Jim Romanski

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Posted 19 January 2013 - 05:36 PM

I have an AT72 and I use the 17mm Ethos mostly for low power use. Sure I could go longer focal length but most of the time the 17mm gives me the view I want.

I also use a 10mm Delos and a 3.7mm Ethos SX with it. I can grab this scope with an eyepiece in the diagonal stuff the other 2 in my pockets and head out for a quick view of all the nice winter sites.

#4 Jon Isaacs

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Posted 20 January 2013 - 03:49 AM

Price range? Undecided.

Recommendations and comments appreciated.

Price range is a biggie..

If you have access to dark skies, then I would be looking at maximizing your true field of view while maintaining a reasonable 5mm exit pupil. This points to two eyepieces, the 31mm Nagler and the 30mm ES 82 degree. These should provide a 5.6 degree TFoV...

I have an 80mm and a 101mm that provide a 4.5 degree TFoV and an ST-80 with a 2 inch focuser that provides a 6 degree TFoV... the difference noticeable and worthwhile.


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