SCT with focal reducer, OAG and Atik 314

[earth titan]

Hi Folks.

With Jupiter coming round fast, I'm torn between using my C9.25 and my 80mm APO in the obsy. So..........

Does anyone have a diagram or photo showing how a SCT, focal reducer, OAG and CCD all fit together? Any examples are good as I'm trying to make sure I get all the bits I need, as I'm contemplating fitting my C9.25 to the mount in the obsy to reduce set up / strip down times between imaging and visual rigs.

[riklaunim]

http://deltasky.pl/wp-content/uploads/2011/07/setup2.jpg - something like this?

[earth titan]

http://deltasky.pl/wp-content/uploads/2011/07/setup2.jpg - something like this?

Thats excellent. Cheers.

Anyone know what the silver tube is between the focal reducer and the OAG?

[riklaunim]

That's T2 spacer to give more distance from the reducer to the primary camera.

[earth titan]

Cool.

I've seen the back focus from a Celestron focal reducer quoted at 3 inches. Is that the reason for the extension tube?

[Freddie]

I'm assuming though that for Jupiter you will not use the FR

[earth titan]

I'm assuming though that for Jupiter you will not use the FR

Very true.

Hopefully, it will be the ease of removal that wins out.

[riklaunim]

I used smaller SCTs for some DS imaging (C8, and the C11 from picture). That worked more or less, but it was to wind fragile on open space, and I wanted even lower resolution (big pixel camera would be cool, or smaller than Atik 314L+ and f/3.3 reducer). For planets SCTs rock, but that on ~f/20 depending on camera.

[Stu_2011]

http://deltasky.pl/wp-content/uploads/2011/07/setup2.jpg - something like this?

It's always hard to tell from pictures but this doesn't look right to me, the quoted reducer to CCD spacing for the Celestron reducer to work at F6.3 is 110 mm. The spacing in the attached picture looks much more than that.

It will still work but won't be optimum.

Thanks

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[Ludd]

I don't know: on my C8 I have a silver T2 extension tube of about that length to get 110mm behind the reducer/corrector lens. 

[Stu_2011]

Yes I have a very similar length tube for my 925 but the arrangement in the photo has this tube + OAG + filter wheel + spacer. It all looks like too much distance.

As with any reducer getting the spacing right is critical.

Thanks

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[todd8137]

What I want to no is how to attach a oag to the 6.3 reducer ,what do I need ?

Pat

[riklaunim]

What I want to no is how to attach a oag to the 6.3 reducer ,what do I need ?

Pat

If you use Celestron OAG (the old long one) then it has a SCT thread ready to go. T2 threaded OAGs will need this adapter.

[earth titan]

Well. My OAG arrived and my focal reducer. Hit a snag though... Grrrrrr..............

The spacer provided by Celestron, that connects to the back of the focal reducer, is too long.

When I try to fit the OAG it clouts the back of the filter wheel. I've drawn quick sketch to show what I mean.

What I need is a shorter Celestron spacer so I can fit more spacers to the back but I can't find anything that suits..........    

Any advice appreciated.

[earth titan]

In fact, a quick conversation with Bern at MA, a revelation.

The OAG is in the wrong place. Needs to be in front of the filter wheel or it won't pick up a guide star.

Soooooooo off to the adaptor box, and try to screw together something else..

[riklaunim]

If a T2 male thread is blocking the wheel from moving then you need a counter-ring to lock it before it goes to deep. And you may also need some short T2 spacers to focus OAG and the primary camera.

[earth titan]

We'll I've just ordered 2 adaptors which should allow me to fit everything together. Fingers crossed.

[Davey-T]

Sorry only just seen this thread so just a couple of pics of my 10" SCT with 6.3 f/r Atik OAG, Atik EFW2 Filter wheel and Atik 314L+ with 2" SCT visual back screwed to the f/r the distance to the CCD chip is about 110mm 

without any spacers.

Apologies for picture quality. 

Dave

 

[earth titan]

Cheers folks.

Well the adapters arrived and hey presto, it all screws together.

One of these was the key:

http://www.ebay.co.uk/itm/like/161093754995?hlpht=true&ops=true&viphx=1&lpid=95&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=95&ff19=0

Very low profile and perfect for the job.

Spacing is around 105 - 110mm. Just got to wait for the full moon to bug out so I can really test it.

[Magnum]

Here is my latest setup with my Meade 8" SCT and Celestron radial guider ( OAG ) + Starlight Xpress SXVF-H9C, with a spacing of 160mm. Increasing the spacing gives me exactly f5.3,

Vignetting is not a problem now as its actually vignetting the whole frame so this means that the frame has completely even illumination, though it does mean I'm loosing about 1" of aperture, but my images are definitely better than when using the stock spacing of 105mm.

If the same spacing was used on a 10 or 12" act there would be no loss of aperture as the larger sct's have a larger baffle tube.

Lee

[earth titan]

Here is my latest setup with my Meade 8" SCT and Celestron radial guider ( OAG ) + Starlight Xpress SXVF-H9C, with a spacing of 160mm. Increasing the spacing gives me exactly f5.3,

Vignetting is not a problem now as its actually vignetting the whole frame so this means that the frame has completely even illumination, though it does mean I'm loosing about 1" of aperture, but my images are definitely better than when using the stock spacing of 105mm.

If the same spacing was used on a 10 or 12" act there would be no loss of aperture as the larger sct's have a larger baffle tube.

Lee

Thanks Lee.

Interesting read. Not had a chance to check mine yet (clouds or full moon, or too much work) but form what you are saying the spacing makes no difference on achieving focus just on getting the right F ration. Is that correct?

[Magnum]

Yes, Sct's are extremely flexible in this regard as they have a huge focus range and back focus.

Lee

[earth titan]

Now that is of interest as I could do with more clearance. To get to F5 ish would be fantastic with the little Atik 314......

But it really is a 'suck it and see' project having not played with an OAG before.

[todd8137]

If you use Celestron OAG (the old long one) then it has a SCT thread ready to go. T2 threaded OAGs will need this adapter.

It's. to tne celestron it's this one

http://www.firstlightoptics.com/off-axis-guiders-oag/off-axis-guider.html

Pat

[riklaunim]

Nope, that's the new one. I used radial guider