Hey suzie, i just had a fiddle around on that site, it seems to me that its pretty skew if. Why do i say this? because apparently my 10" scope with a 20mm ep will show Jupiter up no bigger than a ball point pen point. and that a 1200mm by 254 mirror is F5 which it isn't . Be wary of sites like this as they don't really give a true representation and its only somebody's view point/programming that your relying on.
Best way is to get out and look with your own eyes!
Brendan
