Quote:
Originally Posted by dhumpie
I once had my Vixen/Celestron with its enhanced coatings next to a standard 6" f/5 chinese made scope and there was clearly a difference in brightness. In fact I can boldly claim that the brightness in this scope nearly equalled an 8"
|
Darren, Did you have each scope operating at a magnification giving the same exit pupil diameter? If not your impressions may have been erroneous.
Pre enhanced C8's before the 'Starbright' coating and magnesium flouride coated correcter had very poor transmission. Counting the star diagonal , 3 reflections at 88% as well as 4% loss each side of the correcter plate, plus a 40% secondary obstruction at the baffle.
This amounted to 0.88 X 0.88 X 0.88 X 0.92 X 0.86 = 0.54 or 54% total transmission at the eyepiece.
I'll never forget my first C8 in 1979 for which I'd cooked about 20,000 hamburgers to pay for. My homebuilt 6" F8 reflector blew it away
