From: joe@montebello.soest.hawaii.edu (Joe Dellinger)
Subject: Re: Russian Maksutov (long)
Reply-To: joe@montebello.soest.hawaii.edu
Organization: School of Ocean and Earth Science Technology
Date: Sat, 3 Oct 1992 10:23:25 GMT

In article <1992Oct2.121754.12973@cs.ucf.edu>, clarke@acme.ucf.edu (Thomas Clarke) writes:
|> Has anyone bought the 6 inch aperture Russian Maksutov
|> telescope?

	Yes!

|> If so, how is it?  Optically?  Mechanically?

	I do not own one myself, but did get to use one at the Oahu star party
last weekend. It was quite a compact and handsome little instrument. The optics
were good, but not perfect. Star testing showed that it was very well
collimated and free of astigmatism. The zones were not equally bright on
either side of focus, however. The person who bought it was told that if
he were willing to wait the person shipping them would try a few out and
"ship him a good one"; but he wanted it in a bit of a hurry. He was also told
if he wasn't satisfied he could ship it back and they would try again.
The owner was debating it. Saturn was definitely sharper in the nearby
5-inch AstroPhysics Refractor. Then again, the refractor was nowhere near
as portable and a whole lot more expensive, and Saturn looked pretty darn
good in the Maksutov.

	The design is a little sophisticated: all the surfaces are spherical,
but the radius of curvature of the secondary is NOT the same as the radius
of curvature of the inner surface of the corrector plate, which is supposed
to be a better design that you usually get in Maksutovs. (If the curvatures
are the same they can just figure one curvature on the corrector plate's inner
surface and spray a reflecting spot on in the middle, which is cheaper.)

	I didn't get to slew it around a whole lot, but from what little
sweeping I did it seemed OK mechanically. I didn't particularly like
the focus assembly: it's the twist round and round kind, and I had to
twist it a LOT to accomodate my nearsightedness. But that's just an opinion;
the owner was quite satisfied with that aspect.

	The carrying case for the optics is a black near-cube. A nice
innovation: the free parts screw into the case, so all is held firmly in
place. It didn't look to be quite the right size to fit under an airline
seat, unfortunately. A little bit too wide.


	As for myself after much comparison I'm biting the $$$ bullet and
ordering an AstroPhysics "traveler". I must say the AstroPhysics people
are really fanatical about what they make. A month ago I called to ask
some questions about optics, and they put their head optician (who is
also the owner of the company) on the phone. After establishing that
I knew a little about ray tracing he gave me a "core dump" of information
that lasted over an hour. [It was ironic to have inflicted on me what I am
always accused of doing to everyone else!]

	Some of his opinions, as far as I can remember them (I called them
at 3AM my time to get good long-distance rates):

1) He really likes Nagler eyepieces; he uses the 4.8mm to star test scopes
   before shipping them out the door. They make about one scope (of each
   kind?) a day, and test them thoroughly before shipping.
2) Their scopes are "not expensive for what you get". The objective glass alone
   in a Traveler costs _them_ $400.
3) The Televue Genesis is fine at lower power, but the Traveler can do both
   low power and high power. At higher power the Genesis design ("which is
   somewhat of a compromise") starts to "have problems". (He said exactly
   what he meant by problems, but it was technical and I can't remember it.)
4) Refractors are "far superior" to Schmidt-Cassagreins for splitting close
   double stars, especially unequal ones.
5) The Vixen Lanthanum eyepieces are "a marketing ploy" and not very good.
6) While he likes most of Televue's eyepiece products, he doesn't like their
   Big Barlow which is why Astrophysics makes their own.

	I'm not sure I agree wholeheartedly with him on point #1; at the
star party we tried both Plossls and Naglers in the 5-inch Astrophysics
that was there. It is true the Naglers gave a super-wide field of view
that was sharp ALL the way across... but it was also an image that was
quite noticeably _dimmer_ than the view in the Plossls (I suppose because
the Naglers have many more pieces of glass in them) and the view in the
center "sweet" part of the Plossls seemed sharper than the "equally-sharp-
all-the-way-across" view in the Naglers. I think both Naglers and Plossls
have their uses; certainly I don't agree that Naglers are in all ways
superior. A Plossl with a good Barlow should work quite well in a Traveler.

	It does seem worth it to me to shell out the $335 (cough!) for the
Televue 35mm Panoptic, as the optician at Astrophysics highly recommended.
This in effect turns the Traveler into an absolutely amazing pair of 17x105
binoculars. (For one eye at a time!) For very large extended objects that's
a very nice ability indeed; he said he likes to use the Traveler to photograph
wind surfers on Lake Michigan.

	As for a mount, after trying several out I decided on the "Super
Polaris". It's somewhat cheaper than the AstroPhysics Alt-Az, and it's an
_equatorial_. I talked about this with AstroPhysics as well; for a nominal
extra fee you can now get a converter that will allow a Traveler to be mounted
on a regular camera tripod. For using the scope as a good F5.8 610mm telephoto
lens I think that should be good enough, and a lot lighter. I wouldn't want
to backpack with a mount good enough for high-power astronomy, but it would
be nice to also be able to use the Traveler to take pictures of Hawaiian birds
like Apapane that you usually have to hike a ways up into the mountains to see.
Having a light tripod for that and a good airplane-portable equatorial for
astronomy seems like the best way to go.

	Anyways, better hurry if you want an Astrophysics Traveler. If I order
NOW they said I may be able to get a Traveler "late March or April". And with
the plummeting dollar, their products must be starting to look quite reasonably
priced in Marks and Yen. On a completely unrelated vein, for those of you
actually interested enough in astronomy instead of bashing other people to
your own world view to have read this long-winded message through to the end,
the postmaster on Hannu's system is huttunen@tnclus.tele.nokia.fi . (The
"finger" port on their machine is not enabled, but the "expn" option of the
sendmail port is.) She seems to be a reasonable person, quite embarrassed
by the way an employee of her company is choosing to make an absolute idiot
of himself on several sci newsgroups. I think I now understand the mindset
of the people who burned my ancestors at the stake in first Spain then Mexico.

     /\    /\    /\/\/\/\/\/\/\.-.-.-.-.......___________
    /  \  /  \  /Hawaii Institute of Geophysics, Honolulu\/\/\.-.-....__
___/    \/    \/Joe Dellinger, Internet: joe@montebello.soest.hawaii.edu\/\.-.__
____________________________________________________
Objectivity is NOT an unobtainable EMPTYING OF MIND |
but a willingness to abandon a set of preferences   |----> Stephen J. Gould
WHEN the WORLD seems to work in a contrary way.     |
Newsgroups: sci.astro