I've always been told to buy a lower F number telescope. It'll make astrophotography easier, faster etc.
This however is misleading. What it will also do is make the images smaller/and increase the FOV for the same eyepiece.
If I was photographing Jupiter for example with two different telescopes of the same diameter but different F ratio's people are claiming it'll be faster with the scope with the lower F ratio. Sure thats true if I want a smaller picture of Jupiter, but, if I want the same size picture they will be identical in brightness (all else being the same).
The photons collected are dependent on the diameter of the receiving lens not the ratio of of the lens.
So if you want wide angle photos get a low F number scope or a longer eyepiece on a longer focal length scope.
If you want high magnification, it makes no difference in practice.
Here's the catch, DSO's.
If you want to photograph one of these it would really make little difference in practice what your focal length is. To get the same size image on film/CCD will require the exact same time on scopes with the same diameter.
I posted this on another forum so rather than repeating it I'll provide a link.
It may help others understand or if someone can disprove it I'd be grateful.
http://loresinger.com/FWIS/viewtopic.php?p=12925#12925