[APML]: 500-700 mm range

[charles@jon.cjfny.org]

OK Wierd question. I'm high on the flu right now. I'm looking for the
sharpest instrument with a budget of about $2500 Max that has a focal
length of 500-700mm for astrophotography. Something exotic might be
interesting, but I am not into fidgeting with film chips. Sharp is
crucial. I'm tired of piggyback to 200mm and squinting to make out
various deep sky objects. I also want a fast system, with no color
problems or coma.

Right now I'm considering an AP Traveller or a Peter Ceravolo scope. I
would like to know more about the Takahashi Epsilon-series astrographs.
Any other suggestions for this focal length? There must be other
choices...

Charles