Re: [APML]: 500-700 mm range

["Frank Schiralli, Jr." <schiralli@mindspring.com>]

A>charles@jon.cjfny.org wrote:
>
>>
 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

Might I suggest one further candidate.  I own and really enjoy a Brandon
94mm F/6.7 (630mm) triplet achromat made by VernonScope.

It meets your criteria in several respects;  it falls squarely in the
middle of your focal length,  it is tack-sharp across the entire 35mm
field, has a 2" focusser so no vignetting, shows virtually no color
problems, and can probably be found (second hand) well within your price
range.
I bought mine (probably 8 years old) from VernonScope and it looked factory
new when delivered, and was star tested and "certified" as excellent.
After nearly 2 years of ownership I can tell you I've never regretted this
purchase.  Some of the finest astrophotographs I've taken have been with
this instrument.

Good luck with whatever you decide upon...

Frank Schiralli, Jr.
Member, Astronomical Society of Long Island (ASLI)
N 40* 54' 28"
W 73* 19' 22"