[Jazza11 (Jeremy)]

I was looking at getting a few more eye-pieces for my collection and decided i want to get a few hyperions probly the 3.5mm, 13mm(or close), and a 21mm my scope is a 10" dob with a f ratio of 4.7 i hear that if u have a lower f ratio the better the ep's have to be to get the best views is this true and do u think these are good choses???