Tom Back

That's right. Everybody knows this. Newtonians are the best.

Naw! Coma-free field of view is too small. When it comes to reflectors,
Maksutovs are better by far!

Roland Christen

On 24 Sep 2003 18:08:55 GMT, (Chris1011) ...reflected:

That's right. Everybody knows this. Newtonians are the best.

Naw! Coma-free field of view is too small. When it comes to reflectors,
Maksutovs are better by far!

Roland Christen

Oh, don't say that, sir; not with my Parks already paid for and on its
way!

....and an f/5 to boot!

Alan

Hello, Roland,
Should I infer from your post that the Maksutov corrector does a much
better job in removing coma than the Tele Vue Paracorr does? I am not
disagreeing with you at all, just seeking clarification or a seeking a
statement making a direct comparison of the Paracorr's correcting ability
with that of a Maksutov correcting plate, if you would care to do so.. .
I appreciate your postings on optics and take them very seriously,
indeed I take them as authoritative, and I believe they are one of the
strongest features of SAA. But let me pose a rather different question.
Suppose, hypothetically, that I were a friend of yours who has known you
for a number of years, and someone started a thread called "Roland
Christen" which began as a personal attack on you, and I posted a
discussion of coma correction. Would you draw any implication from my post
other than that I know a heck of a lot about coma?
Bill Meyers

Chris1011 wrote:

That's right. Everybody knows this. Newtonians are the best.

Naw! Coma-free field of view is too small. When it comes to reflectors,
Maksutovs are better by far!

Roland Christen

Should I infer from your post that the Maksutov corrector does a much
better job in removing coma than the Tele Vue Paracorr does?

Any time you insert a coma correcting device in a Newtonian, you do indeed
affect the spherical correction. It may be small but it is not zero.

In the case of a Mak-Cass the coma correction can be 100% (zero coma) over a
relatively large field (as large as you wish). Mike Simmons' original 12" F5
Simak had a 4" fully coma corrected field. At the same time, the field can be
made flat and with zero spherical aberration.

For long focus maks such as my own 10" F14.6, the coma is fully corrected, and
the field is diffraction limited over a 2" field. On axis, of course, the
correction is far below the diffraction limit.

Roland Christen