Novosibirsk TAL 200K Klevtzov Cassegrain

excellent

Very well priced ota in the UK. In fact it is UK£250 cheaper than a celestron 8" sct. I got mine 2nd hand.
Really, really, solid built scope, in a military weapon style birchwood case. Huge !! Has the magnificent Tal 8x50 finder. Uses 1.25" eyepieces only, and comes with an adjustable mirror diagonal. The r&p focuser does the job.
The optics on mine are spot on and this shows in the sharp views. Have had great views of the moon, saturn and various deep sky stuff. M57 was especially glorious.
I'll not be selling this any time soon.
A note to those worried about collimation issues. If your 200K is alligned, it wont be going anywhere soon. But if yours is off, http://www.telescopes-astronomy.com.au/
in Australia has a tool which will get it back in collimation.

Andy.

I purchased this scope because of its peculiar optical design (klevtsov cassegrain), its affordable price, its "small" size, its excellent 8x50 finder and its often excellent reviews. Another reason is that this scope is accompanied with a set of accessories which mean you can start observing right after unpacking the scope!

I was a little bit surprized about the size of the baltic birch wooden case in which the scope is packed :)

After 2 weeks of use, I must say I am very happy with the optical performance of this scope. I get pinpoint star images! Unless others I have a rack and pinion focuser with no play at all. However I envisage replacing it with a motorized focuser some day, allowing me to focus without vibration problems (I observe most of the time on a concrete patio). The finder is easily adjusted (hint: also set your crosshair in RA and DEC) and has an excellent optical quality.

This scope came with the new TAL GEM3 mount (with illuminated polar finder) on a steel pier. The mount has a 12VDC stepper motor instead of a 12VAC clock drive motor (as in the GEM2). It correctly tracks the objects, most of the drift is due to polar misalignment. Polar alignment is fairly accurate. There's a reference screw on the pier, which you should roughly point north (northern hemisphere assumed here). The mount head provides 2 bolts which can be used to finely adjust the north direction (unlock in one direction and lock in the other direction). Polar height is adjusted with a worm and wormwheel which is operated by hand (my mount has a little play here; I'll remove that play with a set of washers).

There's one peculiar thing with the DEC axis: it is much more sturdy to move, and the reason is that it uses slide bushings instead of bearings. The very positive advantage is that there's absolutely no play in Declination. Slew rates in RA are very slow (about 0.25x to 0.5x I guess), and the stepper motor only rotates in one direction. This is explained by the single-axis drive. One important fact on the GEM3 mount: you MUST NOT rotate the RA knobs while the RA motor is running. If you know this, then there's no problem at all. Otherwise you may damage the mount (I was told this in the shop where I bought mine).

Regarding vibrations, I observe on an "unforgiving" concrete patio, so vibrations can't easily move to the ground. The counterweight shaft is 14" long (40cm) and about .75" (18.5mm) in diameter. I think vibrations can be reduced by adding an extra counterweight and moving the entire counterweight "mass" closer to the mount head. If I don't touch the scope, I don't get any vibrations.

The scope is easy to use, but the telescope parts are rather heavy. This is not a scope you'd give to a 12yo kid, unless it's permanently mounted or an adult is always present when setting up and packing the scope. It takes a little practicing to deal with the DEC axis stiffness. The scope cools down very quickly (15-30 minutes). Sometimes I have to search for the RA and DEC lock levers, but that's a matter of exercising :)

I must say I am delighted with this scope. Maybe one day I'll buy another mount for this scope, but that will only happen if I envisage photography and CCD. Otherwise this scope (and the mount) is really worth the money!

Best regards,

Olivier

The (cheap) focusser should be better. Only 1,25 inch oculairs can be used. The Tal Gem mount is to light. Better use a H-eq5 or a eq6.
Sorry, but the optics are mutch, mutch better than a Celestron C8 or a Meade LX90/LX200. Why a 9? Only a Tak Apo earns a 10.

Bert

Optics is quite good, maybe not superb, but realy good.
But mount.... well its not a mount, its a poor joke :(

I had two of them: the first one went back to the shop for aligment (collimation) which turned out to be impossible. So I got a replacement (newer) 200K and I 'm very pleased with the optical performance

Excellent scope for the money. Built like a rock, has withstood a couple of drops. Good eyepieces with it. Pedestal mount a bit low, but still rigid as a rock