M/N 190mm.

[alan potts]

Has anyone set up a Sky-Watcher M/N 190mm with either a 183mc 0r 071mc and are there any special considerations with regards to spacing. Forgive if this is a stupid question and you just connect the camera and use the focuser but I genuinely have no idea. I was considering trying the 183mc at 2x binning, this again a new venture for me to get into.

If it helps back focus of both cameras is 55mm and the F/L of the M/N is 1000mm. I am also considering trying the Zwo OAG on this set-up in an effort to help the guiding, though I could of course resort to the guide scope at 242mm or try a 70mm ED at 420mm, I have a few option open to me.

Alan

[vlaiv]

There is no such thing as back focus for cameras - you probably think of adapters that you used to otherwise reach 55mm required by some field flatteners or coma correctors.

You don't need any of that for MN190 - just attach camera at prime focus with 2" to T2 nose piece and you are set to go. You should be able to reach focus like that - if not, you might need a bit of extension.

No need for any special distance since MN190 is corrected by meniscus disk at aperture.

[Skyline]

No need for spacers on the MN190, if you have the version fitted with a Dual Speed focuser, just use the pull out internal 50mm extension tube if needed.

Nadeem.

Edited February 9, 2020 by Skyline

[alan potts]

6 hours ago, vlaiv said:

There is no such thing as back focus for cameras - you probably think of adapters that you used to otherwise reach 55mm required by some field flatteners or coma correctors.

You don't need any of that for MN190 - just attach camera at prime focus with 2" to T2 nose piece and you are set to go. You should be able to reach focus like that - if not, you might need a bit of extension.

No need for any special distance since MN190 is corrected by meniscus disk at aperture.

Thank you for that, yes I have seen 55mm quoted on reducers and flattener, simple mistake for the likes of me to make, must see if I have a T2 nose piece now, guess I still require the IR/UV filter?

Alan

[Skyline]

Don't think so. I believe that scope has spherical mirrors unless their parabolic.  Not that makes a difference in using that filter.

Edited February 9, 2020 by Skyline

[vlaiv]

2 minutes ago, alan potts said:

Thank you for that, yes I have seen 55mm quoted on reducers and flattener, simple mistake for the likes of me to make, must see if I have a T2 nose piece now, guess I still require the IR/UV filter?

Alan

Not necessarily. You can try without the IR/UV filter first and if there is bloat - then put filter in. Meniscus corrector should not produce much of secondary spectrum on its own - rest are mirrors.

Depending on the camera - you don't need T2 nose piece if you don't have one. My ASI models come with 2" nose piece - you can use that with 2" focuser - just insert camera with that attachment and it should fit focuser. Inner thread is T2 but outer diameter is 2" - same as 2" eyepieces.

[wimvb]

The beauty with this scope is that all critical distances are inside the tube. This means that once you have it collimated, you can just pop in the camera and you're set. If you only use the camera without oag/filter wheel, you may want to add a spacer so you don't need to pull out the extension tube or the draw tube. These can cause flexure. With my ASI, oag and filter wheel, focus is only 10-15 mm from all the way in, and it seems stable. But I put a piece of aluminium tape on the extension tube to make the focuser more stable. 

[Gina]

I've used my MN190 with FW and OAG no problem.  Superb scope.