Combining features of the Maksutov (meniscus corrector) and
Schupmann medial (Mangin mirror) designs, the Klevtsov is a remarkably
clever optical configuration. The fact that Klevtzov's design
employs only spherical surfaces emerges as a strong advantage
over many other catadioptric systems. Like a fine Maksutov-Cassegrain,
my TAL-200K (serial # 0038) has an extremely smooth wavefront
free of the small zonal errors that are so prevalent in mass-produced
Schmidt-Cassegrains; in side-by-side comparisons with 8-inch Schmidt-Cassegrains
it invariably provides superior definition and light grasp. Stray
light baffling is excellent, no hint of chromatic aberration can
be detected, and stellar images are tiny pinpoints to the very
edge of the field. When the atmosphere is steady, the TAL-200K
easily tolerates magnifications of 400X, and I have enjoyed very
satisfying views of Mars, Saturn, and minute lunar details like
the tiny pit at the summit of the dome near the crater Kies. The
disadvantage of the Klevtsov's open tube seems to be largely offset
by its rapid thermal equilibration. In my opinion, it is a viable
alternative to far more expensive Maksutov-Cassegrains. Thomas Dobbins, Contributing Editor, Sky &
Telescope magazine, renowned expert on the history of solar system
observation.
The TAL-200K is a wonderful instrument and I would like to thank
you and your company for producing such a fine instrument. I have
much experience using many quality instruments, but yours is among
the finest. I look forward to many future observations of the
planets with this instrument. I am also looking forward in the
future to the development of the 25-cm and 30-cm Klevtzov-Cassegrains
which will increase my resolution gain even further. I hope that
other observers/imagers discover your wonderful instruments. The
best of luck to you and your company in the future. Carlos E. Hernandez, well-known planetary observer
specializing in Mars.
Bill Brady. Harwood Maryland, USA. A retired RCA (Radio
Corporation of America) and OAO Corporation spacecraft operations
and systems engineer, Bill worked the NASA SAS (Small Astronomy
Satellite), IUE (International Ultraviolet Explorer) projects
and is most proud to have received the ASTP (Apollo Soyuz Test
Project) international award given by the 3 Astronauts and 2 Cosmonauts
to the support team. He spent six years on the Space Telescope
project. He has been an amateur astronomer since the 1960's and
is most interested in visual "hands on" observations.
Bill is the list owner for the TALScopes
eGroup and owns 3 TAL telescopes.
The performance of the 200K on Mars was very much better than
the 250mm SCT I had been using showing a crisp, solid disc with
good colour and no sign of breakdown under high magnification.
Stars present as pinpoints right to the edge of the field and
their colours are far more noticeable. ... I would not hesitate
to recommend the 200K to any aspiring astrophotographer. Tom Barrett, Australia.