T-Adapter vs Focal Reducer vs 2x Barlow

[Stian]

Hi,

So finally it looks like clear skies tonight. I was planning to try some images of M57 tonight and being a total beginner I was hoping to clearify which setup I should use.

So I have:

Nexstar 6SE (on standard mount with Celestron pro wedge)

Canon EOS 100D

T-Adapter-SC

6.3 Focal reducer

1.25" Universal Barlow and T-Adapter

This means I could go for only the T-adapter or T-adapter + focal reducer or connect my camera to the 1,25" 2x Barlow.

When viewing different objects in the sky, what is recommended to use? F.ex M57?

br

Stian
 

[MARS1960]

Personally being dead new myself i would leave the barlow out of the equation, this only makes imaging DSO's twice as difficult for a beginner.

[jsmoraes]

Hummm, perhaps you will have some problems.

1- Canon has very internal sensor, you can have problem to get focus. Your focuser may not have movement to focus.

2- that focus difficulty can be worse if you use focal reducer. The focus will be more internal to the focuser.

3 - Barlow use will facilitate that focus, since the image will be sent further away from telescope.

I think you may begin with barlow and Canon. Try without barlow, after. And try with reducer.

You may experiment with and without diagonal, also. Without that diagonal you can find more internal focus.

note: if your barlow permits, you can try 2x and 1.5x mode. This last, with the lens only; without the extensor (barrel).

[brantuk]

The 6SE has an f-ratio of f-10 which definitely wants bringing down. The .63 reducer will do that - whereas a barlow would raise it further. Also - I would use the reducer at native focus - so remove any diagonals and attach it straight on the visual back. It should have a t-thread for direct camera attachment iirc - so all you'd need is a dslr t-ring.

For any LE dso imaging you want to get as near to f-5 as possible (or less) which is why Sct's aren't the best tool for that (what with their narrower fov too). But it is still possible. Hth

[cjdawson]

The setup I used on my 8" LX-90 was as to use everything except for the barlow.   Yes, focus is critical when it comes to M57 I had a go at it a few months ago.

Here's the link to that thread, along with my results.

http://stargazerslounge.com/topic/254122-first-attempt-on-m57/

If I was going to have another go.  I'd do the same setup again and spend more time focussing.