[Wavytone]

Rob,

These scopes are long focal-lenth and their primary role is high magnification views of planets, moon, double stars. They're not ideal for low power wide fields, if that is your thing. Short of buying an f/15 APO refractor of the same aperture (expensive, big and bulky), a good f/15 Maksutov is the next best thing. If you are thinking of one, you may have to re-think your eyepiece collection to suit a long-focal length scope.

With all the maks from 7" aperture and up, cool-down time will be an issue if the OTA is not ventilated. The usual symptom is that while cooling down the air inside settles into a laminar flow driven by the thermal gradient inside, and the result is a rather weird "spike" degrading star images. Either wait and hour or so for this to stop, or move the tube rapidly to break up this air current.

With respect to quality of Maks, there are:

1.Questar, well known for their various 3.5" and 7" models. The best of the best and set the benchmark for all. Questars are ostensibly perfect, optically outperforming just about anything of comparable aperture and mechanically they are works of art. If you own one you will probably keep it for life.

Questar have a range of mirror and corrector coatings designed to last a very long time, and in addition provide full service if you wish to have an older one refurbished.

b) Quantum. Started by some guys who left Questar, there were 4", 6" and 8" models. Direct competition to Questar at the time, they were optically excellent. However: These scopes are now 20-30 years old which means the mirror coatings won't be in great nick. In addition its not at all clear whether the correctors were antireflection coated, some of the photos imply they weren't which means theres a 15-20% light loss for starters. With poor mirror coatings, transmission could be as low as 50%. Need to consider whether you're buying a collectible museum-piece, or a scope that you will actually use regularly.

c) TEC. (Telescope Engineering Company). Makes big maks from time to time, optically these are superb but huge, heavy, expensive and really only suit an observatory.

d) A few odd-ball big maks are offered from time to time through APM in Germany, mostly using high quality russian optics, assembled to order. These are usually listed on Astromart - when available.

e) Dynamax. Another attempt to copy Questar, complete rubbish, steer clear.

f) Meade 7" f/15. The Meade 7" Maks are excellent optically and if you can find one, buy it. Only thing to note is that the ones in the fork mounts had a heavy iron weight in the back to balance the OTA in the fork, some of the de-forked ones have had this removed which also improved the cool-down time.

g) The russians: Intes / Alter / Intes-Micro / LOMO. The russians made excellent maksutov and maksutov-newtonian optics, various sizes from 6" to 12" and focal ratios f/8 to f/20, and you can still buy one of these. Excellent choice if you can handle the hassles of buying one, or pick one up secondhand.

h) Celestron. Made a few small maks from time to time, mainly spotting scopes.

i) Skywatcher. Cheap chinese clone, optically not in the same league as the russians or Questar, but mine is nonetheless a fine scope. 127, 150 and 180mm apertures. One aspect of my 180mm f/15 Skywatcher is that its about the smallest mak that has a proper 2" back for big eyepieces. If you have a chance to try a few and hand-pick one, I would because you could get a really good scope at a bargain price.

j) Saxon. Cheap chinese clones, 90, 125, 150 and 203mm apertures, optically OK.

k) Orion. Orion in the UK sold a few maks, up to 8", probably rebadged chinese clones.

l) Bosma. Cheap chinese clone.


A few oddball copies appear from time to time in smaller apertures but these are the main ones to watch for.