TAL 200k review.

[rawhead]

Wow a 250K :)

Let us know how you get on with it please..

Cheers

Jon

Ah,

Ok cheers for that Mark.

It seems the norm that the OTA is £1899. Then its the mount for your choice. Upto now its the HEQ5.

These scopes should perform excellently with the DMK cameras. Cann't wait.

Eddie

[riklaunim]

The question I have - how this design works in UV. Like in a SCT the light goes through a glass. If the lens/corrector is made of something like BK7 then up 340/350 nm is cut out. I don't expect it to be made of fused silica, but it's probably something better than standard optical glass. Non-glass cat is GSO 10" RC but RCs have big secondary and fancy colimation. It's so tempting to get the 250K...

[astroeddie]

Guys,

Extensive search has came up with this excellent review, with images taken extra...

TAL 200K OTA Review Nenad Filipovi?'s Homepage

Seem a great scope,

Eddie

edited after further reading

[AndyH]

I found a Russian blokes stripdown and more, of a 250K. I posted the link in our Tal Users Group

Stargazers Lounge - regarding the Tal 250K

Great pics, gives a better understanding of the mechanics of the Klevtsov range.

Andy.

[spaceboy]

Braver man than me! I need to touch up on my Russian though

[astroeddie]

question guys,

Everyone who contributes to threads on the Mak topics are VERY concerned about cool down.

I always stand my scopes outside with the open visual back facing up to help cooling. (ie ... no diagnol inserted) Usuallyfor around 90 minutes.

Is this sufficient for Maks, Tal 200K especially?

I could leave the scope in the shed all day if needed.

Cheers once again .... Eddie

[sixela]

question guys,

Everyone who contributes to threads on the Mak topics are VERY concerned about cool down.

It depends a lot on how large a scope they're talking about. The mirrors in 180mm Maks are a lot thicker than in smaller scopes, so cooling them is harder.

The problem is also dependent on the temperatures over the night. If temperatures keep dropping, you may need forced ventilation (using something like a Lymax cooler) from time to time to make the mirror track the temperature again. If temperatures during the night are stable, your strategy of simply allowing them to accommodate to the ambient temperature will work.

The corrector itself cools rapidly (indeed, too rapidly, and when it becomes cooler than the ambient air may dew up, so you'll need a dew preventation system if you have a lot of nights with high relative humidity).

but the Tal 200K is not a "classical" Mak, but a design derived from it with a subaperture corrector designed by Klevtsov, and actually cools very much like a Newt (without a fan) would.

[rawhead]

The 200K is not a Mak. It's a Klevtsov. The tube is open at the top (like a newt)

Cool down is therefore much quicker than a Mak (or an SCT...)

Another cracking review: The Novosibirsk TAL 200K Klevtsov Cassegrain - Review

Cheers

question guys,

Everyone who contributes to threads on the Mak topics are VERY concerned about cool down.

I always stand my scopes outside with the open visual back facing up to help cooling. (ie ... no diagnol inserted) Usuallyfor around 90 minutes.

Is this sufficient for Maks, Tal 200K especially?

I could leave the scope in the shed all day if needed.

Cheers once again .... Eddie