ATM 10" F/4

[Mike Pence <mpence@avalon.net>]

Recently I've seen some people talking about problems with the faster
10" telescopes.  I am having a 10" F/4 polished right now and wasn't
aware of needing a corrector lens or anything of that sort.  What
problems will arise from the short focal length that I will need to
correct and what problems are there going to be that won't be a big
deal?  And, since I am hoping on giving this 10" scope I am building to
my parents and then building a 12.5" for myself to keep, is it going to
make things ever worse if I go with an f/4 or f/5 on the 12.5"?

Thanks.