Hi Alex,
Good report mate -- a nice read much enjoyed.
Alex wrote:
"1: M104. The Sombrero Galaxy.
Viewed through a variety of ep's with and without barlows.
I found the best combination to be my 25mm with a 2x barlow, and also found myself itching for more apeture (already.. eeek!!!!)"
You've serendipitously stumbled across something important here -- the 2mm exit pupil "rule".
For small low-contrast objects (like galaxies, globulars and most planetary nebulae), as a rule-of-thumb, a telescope will produce best possible contrast when you use an exit pupil of about 2mm.
In this case 1200mm / 25mm ep = x48 magnification plus the 2x barlow = x96.
200mm aperture / x96 = 2.08mm exit pupil = best contrast!
Best,
Les D
Contributing Editor
AS&T