Hi Ian,
It's an f5, an f 4.5 if I cut it to ribbons
. I have removed the primary a few times, distilled water, etc. My fault, I let the elements in once or twice.
The BT-252 comes standard with a 2" Crawford, not the smaller.
It really comes down to keeping this scope, which I doubt is worth it, considering a new mirror in comparision to the cost of the whole scope.
Thats what the GSO's are famous for, bang for buck, and the aperture/mirror, is your bang with newtonians.
I liked Barrys ( earlier post ) comment. If his son can shoot away dozens of frames on a more forgiving scope, perhaps the way to go. Then Erics comment re the 8" refractor - viewing/goto/photo/all in one for less than $2,000, allthough I wonder how good those shots would be given that's an 8" on an EQ5 - calculate the extra weight, and those gears, hmmmm.
Now you can see exactly where I lie - there really dosn't seem to be an agreed good starting point.
f/5 - seems to cover most objects, but, for value, you could really only go a newt with that ratio.
Is there a "forgiving" setup, keep my Dob, and still buy something in the 2-3,000 range ? Like I said the ED series.
Ciao
DOC