C6 SCT

[Carole]

Never owned an SCT before.  How do I fit my CCD camera to the back of it?  It seems to have a 1.25" nose piece, but this can be unscrewed.  But the remaining Orifice (for want of a better word lol) seems only to have a "screw in" opening.

A) Do I put my 1.25" nose piece onto the camera, if so I can't use my 2" focal reducer, which is probably not right for an SCT anyway. Does this affect my FOV in the Atik314 & Atik460?

B) Is there a specific Focal reducer that does screw into this threaded opening? 

Initially I just want to check the collimation, but ultimately I'd like to see if it can be used for DS imaging and if it is out of collimation that might be the reason for my weird results on Jupiter this week.

Carole

[RobertM]

A) Unless you can get a 2" focuser or adaptor on it then you won't be able to use any 2" accessories (focal reducers etc.); because of that you will need to use 1.25" fittings.  Field of view is directly related to focal length and sensor size.  A focal reducer reduces focal length and increases field of view so other than that I'm not sure what you're asking.

B) You need either the Meade or Celestron f/6.3 reducer which should work as well as anything else for the money.  That should bring the focal length down from 1500mm to a shade under 1000mm.  It will screw into the back of the telescope but I've no idea what the correct back focus distance should be or what would be needed to achieve that.

The method of collimating that Duncan described is an easy place to start - there is a thread on it somewhere... Good luck finding it ...

Hope that helps
Robert

[The Thing]

Hi Carole,

If you have a 1.25" barlow use that in the SCT adapter you have, the standard SkyWatcher one has a t-thread for the camera. If you get a 2" adapter make sure it has more than one screw or a centring twist lock action, mine doesn't and its hard to get tight.

I use an SCT back to 2" adapter with the 2" barlow lens inserted. The ED barlow lens is removed from its other bits as that give me a 2" thread on the back and I have a 2" to T thread adaptor onto which goes my ADC via an extension tube to restore the balow dimensions, then a T to C adapter to screw the QHY5L-II to. It's a bit of a mix and match of adapters and stuff but it works.

For deep sky work you need an SCT to T-thread adapter. I have a Baader one and an Alan Gee Telecompressor which is a flattener reducer, that proably wouldn't fit you scopes draw tube. Then just screw everything on as normal, loads of back focus available.

Collimation: Look for Duncans Collimation Mask, make one and follow the instructions, easy with a camera attached.

[Carole]

I'm OK with the Barlow and webcam for planetary as this is what I have been using, it is purely attaching my Atik cameras, a FR and EFW that I need to know about.  I can't even check the collimation until I can get them fitted, although I suppose I could just attach the camera with the 2" - 1.2" nosepiece just for that purpose.

I found this today Robert, is this what you mean?  If so, I still don't know how I fit the camera/EFW to it unless the EFW thread will screw directly to it.
http://www.rothervalleyoptics.co.uk/celestron-f63-focal-reducer.html

I took a look at the link to the Duncan mask, but then the link that they posted to SGL is no longer available.
I was just going to collimate using a defocussed star. 

Carole

[RobertM]

That's the one Carole.  If you're buying new then give them that headache .  If you're buying secondhand then you'll need to do some digging.  I used one a long time ago but as I remember it I had the reducer screwed onto the scope and a 2" focuser (with SCT adaptor) on to that.

Robert

[Carole]

Thanks Robert.  Well if they don't know if I can ascertain the thread size and type of thread I can check if it will fit the EFW.  I guess if it all screws up it will help with the dreaded tilt problem I have had with my refractors.

Carole

[RobertM]

The output thread on the reducer is the same as on the scope so you can just think of it as a extension with glass in it.

[Carole]

That's handy to know Robert, so I can try out my FW on the thread on the scope.

Carole

[RobertM]

Refractor tilt problems are mostly down to the cr@p focusers they put on to reduce costs.

[Carole]

I never did find a solution on my refractors, which was one of the reasons why I got rid of my Atik383L.  It doesn't show so much on the smaller CCDs.

I just tried out the Atik camera and filter wheel.  The hole in the SCT is even smaller than the 1.25" nosepiece!!!!
I can fit the Atik camera on it's own with the 1.25" nosepiece onto the SCT and this nosepiece will also fit the FW, but at the moment no means of attaching a FR. 

At least I can do a collimation check.  I am presuming the focal length of the finderguider is too small to use as a guide scope?  If that is the case I can use my ED80 on a side by side bar which i still have.

Carole

[Carole]

OK, I got the Atik460 and FW on the back of the SC6 tonight, and collimated it.  It was only "out" a smidge.

This is what I got at the end of it.



Need to set up a guidescope, don't think I can face an Off Axis guider, heard too many problems from people who are more technical than me.  Then I'll try some DS imaging out, and if I am happy with that I'll get a focal reducer.

Carole