Milton Wilcox R.I.P
Clear skies, Erik
Visual astronomer, main instruments:
Matthias Wirth 16" f/5 Takahashi FS-102 NSV on EM-10 Celestron 1983 C5
Zeiss, TeleVue and Celestron eyepieces
Nikon 18x70 IF-WP Zeiss Victory FL 7x42 Zeiss Victory FL 10x32
Quote:I have ~0.75 diopter of astigmatism, which by good fortune has the same orientation in both eyes. With virtually every bino I've ever used, I find that I can find a sweet spot where eyepiece astigmatism nicely cancels my own. That my astigmatism causes a horizontal smearing, I place my target either above or below the field center by about 1/4 to 1/3 the distance from center to edge, and obtain a very sharp image for critical examination.If the exit pupil goes below about 3-3.5mm, astigmatism is not a problem worthy of compensating.
Quote:Reducing exitpupils will have a great positive impact on the effect your astigmatism has on the (perceived) image quality of stars.For my eyes, with 3mm exitpupils sharpness will hardly suffer, 5mm is a good compromise between sharpness and brightness, while 7mm will show a very bright image with significantly reduced star-sharpness.