Replacement for CPC800 - cracked corrector

[DRCORTEX]

Well people, due to an unfortunate accident, my CPC800 is now cactus. I was using this with Hyperstar for widefield nebulae imaging with an ASI294MC.

The bummer is, it is impossible to find a replament OTA for this scope, and the cost of repairs ( including transport to Celestron in the USA ), is lineball as to cost vs benefit.

So, I have all of this Celestron equipment - Wireless dongle, motorised focuser, eyepieces, masks, Starsense, F/6.3 reducer, on and on.

Based on this, I was considering buying the CGX800 as a replacement - great weight ratio between the CGX ( 25kg ), against the C8 OTA - non edge ( 7.5kg). Should make for a rock steady imaging platform, and I can use all of my Celestron gear salvaged from the CPC800.

Now my question - is this the way I should be going ? I love my Hyperstar, so would like to keep that in the equation, or is an edge a better option, sell the C8 hyperstar, and go an edge Hyperstar with a new OTA ?

I'm especially keen, to move into Galaxy imaging, but is this the right combination. I hear the F6/3 reducer, is really for visual use, not imaging ?

Perhaps I should look at an F/4 Newt on an EQ6-R ? or a 120mm APO ?

I look forward to your thoughts,

Regards,

Lance

[Outcast]

Hi Lance,

Sorry to hear about the demise of your CPC800 OTA...

I'll qualify what I'm about to say by mentioning that I know nothing about the CPC800 or how the OTA is connected to the mount but...

Would it be an option to purchase a new OTA, say an edge HD or C8 & then using parts from the CPC OTA, convert the new OTA to fit the CPC mount?

Just a thought, possible.. no idea

Cheers

[DRCORTEX]

Afraid not, it is a dual fork design, so any OTA would need to be altered to fit into the dual fork, not something I would want to attempt. Pity I just purchased a HD wedge as well.

[Outcast]

Bugger..

I gather from your comment you couldn't just transpose certain parts from one Ota to the other to be able to mount it on the forks?

[The_bluester]

There are six holes in the rear cell of the CPC versions (Four threaded, two for locating dowels) that are probably not present in a non CPC tube. It is easy to defork a CPC (I have done this with my C925) but probably a lot harder to go the other way.

[DRCORTEX]

Yes, CPC800 OTA's are different, the screw holes, etc, do not match your standard C8 OTA. Deforking can be done, it's reforking that is difficult. I'm leaning towards a standard C8 on an a CGX, the extra payload capacity would mean I can grab a larger/better OTA at a later time, and still use all my current Celestron equipment. I see opticescentral has the package for 5199 at the moment

Cheers,

Lance

[Camelopardalis]

Yikes! That's an unhappy incident :sadeyes:

Unless you intend to image at f/7 or f/10, then there's no advantage I can see to the EdgeHD model. For Hyperstar, you're not using the corrector elements that are located in the baffle tube.

FWIW I use an older CPC mount, with one arm removed and a dovetail clamp added to the remaining arm, and have used the mount with scopes up to my C11. Of course, the mount was from a CPC1100 to start with ;) But it's a versatile setup for a bit of visual or planetary (although I find the backlash to be a little more than I'd like for very long focal length work).

[DRCORTEX]

Just setting up for tonight now. It will be interesting to see how the Hyperstar performs with the cracked plate. That light still has to go through the corrector plate then primary, to reach the Hyperstar optics.

I did try Jupiter with an ASI290MC earlier in the week. The results were less than good. I could make out the features/colour, but very blurry. Hard to tell whether it was simply bad seeing, or the optics thrown out by the corrector. The secondary was collimated, and it looked fine. However, the artificial star, did show the cracks from the plate when imaged. I was going to use an F/6.3 reducer and try some larger galaxy hunting, but need the 50mm T-Adapter to get the right back focus ( on order )

Cheers,

Lance

[Camelopardalis]

Only one way to find out ;)

I’d be surprised if it spoiled an image...it might give you a diffraction spike? I’m guessing...

[DRCORTEX]

Finished a few images just now, havn't had time to look closely. Will leave for now, so I can take some time, to go throw the differing sets. I will post a few sample.

Cheers,

Lance

[garymck]

Have you contacted Celestron in Australia. Perhaps they could bring in a C8 OTA that would fit your CPC mount? Should cost no more than a standard C8 OTA?

FWIW
Gary

[DRCORTEX]

Afraid not, the CPC800 OTA is dual fork, you cannot buy the correct OTA, they differ from a C8.

Cheers,

Lance

[DRCORTEX]

Well, It dosn't look too bad, Hyperstar needs collimation. Shot of Eta Carina from last night. 1 X 5sec sub. No processing

[Camelopardalis]

Can’t really tell at that image scale, but there are plenty of bright stars in that field to look at...inspect them closely, but if the stars look OK, and the corrector isn’t going to crack further and smack your camera into the main mirror, then you’re good to go :thumbsup:

[netwolf]

U might find a previously deforked c8 or alternatively you could see if a single arm modification could be done on the cpc800. I know it has been done on the cpc925 and cpc1100. If you convert to single arm then you could add any c8 Ota and or other small ota and refractors on it.

[Sunfish]

My worst nightmare.

If the cracks get worse:

Toscan optics in Italy will make a new corrector to fit a c8 for maybe 380 euros . There would be a lot of optic tuning to get it to work I think but can be done.

https://www.toscanoptics.com/schmidt-cassegrain-corrector-plate

Failing that you can sell it here to someone who wants to make a new one. People do.

[LewisM]

Replacement for CPC800?.... Mewlon 210 :P


I'll go hide now...