New Imaging Setup - GSO 8" F/4

[RichieJarvis]

I brought a second hand GSO 8" the other week - unfortunately, it wasn't the 'deluxe' model, but at the time I didn't realise this would be an issue. It turns out that the standard model focuser cannot handle the weight of the SXV-H9 and the Truetech Filter wheel (it weighs in at 1.325kg!) which caused me a few problems the first time I tried it.

Thanks to the wonderful service from Bern at Modern Astronomy I got a Baader Steeltrack Focuser to replace the standard GSO model, and am happy to report that the focuser can hold the weight.

Theres still one other problem that I would welcome some advice on though - the focal point on both focusers requires that the SXV-H9 is locked about 18mm out of the focuser. I do have a 35mm and 50mm extension tube, however, both of these tubes make it impossible to achieve focus. I can't find any shorter 2" extension tubes online - does anyone know where to get something to do the job?

Here is a pic of the new setup in the obs:

(click to enlarge)

Here is a closeup of the camera and focuser showing the distance that things are sticking out:

(click to enlarge)

Thanks for looking!

Cheers,

Richie

[GordonH]

Hi Richie

Get in touch with Ashley Stephens at http://www.preciseparts.com in America, they can make any adapter, extension tube, plate, etc, to any specification. I f you email him with your problem he will be able to do something for you. I have used them twice and they provide a very good service. They aren't cheap but you do get a quality product

Best wishes

Gordon

[Tim]

Is that the coma corrector in front of the filter wheel Richie? The Baader MPCC will fit inside the focusser, but I found the fit wasn't especially conducive to getting the camera lined up nice and square.

My train goes like this > TS 35mm extension tube > MPCC > M48-M42 adapter > TS OAG > CLS filter > IR nosepiece > Adjustable Spacer > QHY8.

The whole lot is pretty heavy, especially with the DSI perched on top. The focusser only needs winding out a couple of mm like this. I fit the M48 ring to the MPCC, and butt the extension tube up tight against it for a good fit.

Here's a pic. Dunno if it helps any?

(click to enlarge)

[Eddie]

Thats a good looking scope! I better blow the dust off mine and give it a go!!!!

Eddie

[steppenwolf]

Richie, two things:-

1. Did you resolve your collimation issue, I never did get 'the call'!

2, I realised that I would not be able to get focus on my Skywatcher 8" and 10" Relectors with my Baader MPCC using the 2" EP adapter that came with the mount so I designed my own special adapter that allows the MPCC to be well embedded inside the focus tube - an additional advantage of this is that I designed the adapter to give a very solid and accurate camera alignment. The attached images reveal all:-

[steppenwolf]

.... and the second image:-

[RichieJarvis]

Hmmm - that looks interesting Steve. Any chance you could bring a sample along on Monday to AdurAS? I might be better able to understand how it would work by looking at it (yes, I am thick....) and see if it will solve my issue.

As for collimation, i think the penny is dropping slowly Thanks for the offer!

TJ - my imaging train is like this:

SXV-H9 -> M42-T adaptor -> Truetech Filter Wheel -> 2" T adaptor nosecone -> MPCC corrector

I've labelled up that image:

[steppenwolf]

Hmmm - that looks interesting Steve. Any chance you could bring a sample along on Monday to AdurAS? I might be better able to understand how it would work by looking at it (yes, I am thick....) and see if it will solve my issue.

Hi Richie, will do so,