CPC 800 questions

[Gerontius]

I'm considering an upgrade from an ETX125 to a CPC 800. The questions are:

With the CPC with a dslr & adapter fitted on the rear of the OTA clear the fork assembly when the OTA is at a high altitude adjustment?

If it does clear can it also accomdate a field flattener?

Are there any other clearance issues to be aware of or would I be better off with a C8-SGT XLT?

[MartinB]

My guess is that you will get away with the camera but I doubt you will with the the field flattener. The Celestron 0.63 flattener needs around 110mm spacing between the chip and the back surface of the flattener. Not the end of the world though, you'll still get most of the sky. I wouldn't let it rule out that choice of scope.

[brantuk]

Assuming you are snapping dso's then you would be using a wedge which adds a lot of room at the back of the scope when pointed directly up at the zenith. But you'll have to watch the angles either side of the polar alignment when the tube is in line with the forks. The CPC menus have an option to set angular movement limits

I'll do some measurements at home tonight and come back to you.

[Psychobilly]

With the f6.3 reducer and the additional spacer the 1000D will just clear the azm clutch knob with literally a few mm to spare... so this is going to be highly dependent on the camera that you are thinking of using...

Billy...

[Gerontius]

Thanks for your comments - all noted.

Its not a serious issue as generally I would be aiming at solar system objects - OK they won't be at high altitude but I thought that it was worth asking before spending the money since the etx is very limited in that respect when a dslr is attached and I wondered whether the CPC suffers similar problems.

The dslr would be a Canon 400D. I also realise that focussing may be an issue at high altitude with the camera tucked away between the forks. I do have the Canon right angle eyepiece but that would remove any possibility of using the field flattener.

[Nexus 6]

Hi Gerontius, heres a shot showing my 925, plenty of room although I am not sure if the 800 is exactly identical size wise.

[brantuk]

Here's a shot of the 800 on a wedge - bags of room pointing directly up

Stargazers Lounge - brantuk's Album: Telescopes - Picture

[Psychobilly]

Add a focal reducer and the 55mm SCT-T extension needed for the correct spacing and it gets a lot tighter...

Billy...

[durr]

Kim, just out of interest what make is the wedge and how do you rate it? Steve

[brantuk]

Hi Steve - I have the old Celestron Heavy Duty wedge. It works ok but I had to chamfer a ridge on the Az adjustment bolt so the little collar and grub screw would actually stay in place and make it work properly - which I felt was a bit poor quality.

The more recent ones look like they've been upgraded but I don't know if they've fixed the problem I had. The biggest problem I have with it is price (£250 when I got it) - for a bit of cast iron and some bolts it's way too expensive and the "upgrade kit" is ridiculous at over £100. I think the whole jig is nearer £500 now so look for s/h if you're wanting one.

The main thing though is that it's rock solid steady and works fine now I'm happy to say

[durr]

Kim, thanks for the info and I always appreciate your input. Steve