Quote:
Originally Posted by NGC2264
Would you be able to elaborate on this one a bit more John. What are the big factors for the 26mm over the 31mm to you?
The 31mm would give a 20% greater actual FOV than the 26mm (91.3 v 76.1). I see the exit pupil is quite different 4.8 (26mm) v 5.7 (31mm).
I quite enjoy viewing open clusters and want to make sure I can get en eyepiece that will allow me to put it all in the eyepiece so to speak.
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Hi Gordon,
In a 10"/F5 scope the 26mm Nagler gives 48X with a 1.7 deg TFOV. I rate this about the perfect low power scenario in a 10" scope. Consider that the 31mm Nagler in my 18" Obsession gives 67X and a 1.2 deg TFOV. In addition, I consider the 26mm Nagler to be marginally better optically than the 31mm Nagler. I think it is a touch sharper on axis and contrast is a little better because of the higher magnification (smaller exit pupil). Most importantly however, it is 1/2 the size and weight of the 31mm Nagler which IMO is an important consideration in scopes under 14" aperture.
Cheers,
John B