Newtonian Guidescope?

[BlueAstra]

I have a 8" Celestron SCT (focal length 2032mm, F/10). Could I use my old Skywatcher 4" Newtonian (focal length 500mm, F/4.4) as a guidescope, mounted side by side on my EQ6?

[George]

I don't see why not.

My SW 10" has been my guidescope for best part of a year

[Psychobilly]

Bit like my 8" SCT was then George... although now I use a 500mm f8 telephoto lens as it allows me to image through both the main ota's...

Peter...

[Whippy]

As long as it all balances properly and you can get the camera focused, then why not? On my first couple of imaging sessions, I used my old 5" Mak-Newt as a guide scope while I was waiting for my ZS66.

Tony..

[ollypenrice]

Indeed why not? The only thing about reflectors as guidescopes might be a bit of movement in the mirror from time to time. Our EQ sixes seem to like 500mm guidescopes.

However getting an EQ6 to cope with a focal length of 2 metres might be difficult as far as guiding accuracy goes. People do manage it, however. You'd do better at f6.3, maybe?

Olly

[BlueAstra]

Just starting out in photography. Does that mean I should use a focal reducer on the SCT to bring the focal length down to about 1280mm?

[Whippy]

Not only would it reduce the focal length (even so, imaging at 1280mm isn't easy by any stretch!) but the reducer would make the scope a fair bit faster so you're able to grab more data in a shorter time.

Something like this is what you need: Reducers/Flatteners - Celestron f6.3 Focal Reducer .

Tony..