C6 SCT, Astro Tech AT6RC and Refractor 120ED?

[kimo]

Hi,

anyone used this Telescopes for Imaging? which do you recomend for imaging?

1: C6 with F/6.3
2: AT6RC with Reducer
3: Refractor 120ED

Thanks
Kimo

[orly_andico]

I use none of the above, but I would suggest avoid the 120ED. It is big and long, and would demand a lot from the mount.

[MooEy]

I'm leaning towards the 120ed. Refractors are simpler, doesn't have much issue with collimation, have lots of reducer/flatteners that would work and have less issues with vignetting. If size is an issue, you can consider picking up a smaller refractor instead.

I would avoid anything that says celestron, so the c6 is out. The 6" RC is somewhat more challenging to deal with compared to a refractor. Getting a reducer that would work perfectly would be hard. Given that it's only only slightly bigger than a refractor, I don't really see the point. The larger 8" and 10" are tempting thou. Then again I would not recommend those for someone who is trying out imaging.

~MooEy~

[orly_andico]

The only value prop of the AT6RC is that it is physically small, and gives a focal length comparable to the 120ED.

With the OP's Sirius mount, I'd rather have the AT6RC (even with its focuser and collimation issues) to avoid over-stressing the mount.

[kimo]

Thanks for comments. at first I will try on 6" and 8" SCT with 6.3 and 3.3 focal reducer. must try on few scopes.

[kimo]

I just accrued few telescopes .

1: AT6RC Imaging
2: 6" SCT OTA
3: 8" SCT OTA
4: Focal Reducer F/3.3 and F/6.3, 0.5X, spacer ring, T adaptor, also off axis Guider.
5: some Adm mount adaptor.

I will test all this for Astrophotography. I am not going to keep all so Two OTA must go to new home after my test done.
Now sky is very cloudy so will takes time.

Thanks.

[Mariner]

Nice bunch of eqpt kimo. I suspect you're the cause of clouds the last few days.

Jokes aside, I don't think the f/3.3 FR is meant for use by native f/10 SCTs. Read somewhere they won't work as they are meant for the f/6.3 Meade SCTs. I may be wrong or you might get f/5 instead so do keep us updated on your test results.

[orly_andico]

No, the f3.3 reducers are meant for the normal f10 SCT.

However, they only cover the really small chips like the ST7. In other words, a chip about 8mm x 6mm.

Any more than that and you'll have eye-popping vignetting.

[kimo]

Thanks orly and mooey, I think shouldn't be problem with F/10. May be F/3.3 endup F/5 or less. I know it made is for small chip, mine is DSI II.

I am facing problem with Meade off axis guider as i want to eliminate guide scope. the Reducer works perfectly
Very hard to get the star for autoguide.

[orly_andico]

The OAG should be in front of the reducer.

If the reducer is in front of the OAG, the pick-off mirror will be outside the reducer's image circle.

When I was using OAG, even with a 0.8X reducer, the OAG could not get any stars anymore. But.. I am not using OAG anymore. It was more hassle than it was worth (for me anyway). I just use a long guide scope (560mm FL), this works fine to guide my C9.25 even when barlowed (4700mm focal length).