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  1. T

    Observing the Moon with a spotting scope

    Coincidentally, that is the exact value I measured on my 883 using a 3,5 mm Nagler. Although I had hoped for the Dawes' limit of 1,32", that was probably not on the cards as the element steps on the 1951 USAF chart at around 10% are not going to be surmounted by a small change in target...
  2. T

    Observing the Moon with a spotting scope

    Come to think of it, there are probably not that many birding scopes that offer sharp views at magnifications corresponding to 0,6 mm exit pupil. My ATM65 HD and 883 used to, but nowadays my own eyes are the limiting factor and floaters begin to get annoying below 1 mm. :( John
  3. T

    Observing the Moon with a spotting scope

    Televue sells cylindrical adapters for some of their eyepieces to compensate for the viewer's astigmatism. See chart on the right: DIOPTRX™ It's not surprising that you got sharp views at 0,6 mm exit pupil. John
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