Celestron CPC 8" - what else do I need?

luminary (Ben) · #1 21-03-2010, 08:42 PM

Hi all,

I've just purchased a CPC 8" SCT. I have been out of observing the sky for more than a decade and my last telescope was a Meade reflector that had an equatorial mount etc.

What I understand is that the telescope comes on a fork mount, and only one eyepiece the 40mm in a 1.25 inch size.

Ideally I want to buy everything now for keeps and don't want to muck around with intermediate learning etc. purchases. I've read that 2" eyepieces would be a good idea etc.

To be honest I don't know much else about it. I have a Canon 5D II and a Lumix GF1 micro four thirds camera. I'd like to do some astrophotography too.

Here are some of my questions:

1. Do I need to buy a power supply? What should I buy if so? A Celestron power tank or some other car battery with charger etc? Please suggest products that are easy to use, even if they are a bit more expensive.

2. Which eyepieces should I buy? Stick to 1.25" or move straight to 2"? Axiom or E-Lux in the kits?

3. Astrophotography? Apart from a wedge what other things are a must? An f6.3 reducer? A T-mount for my camera? A T-adapter for the scope? A radial guider? These are just from my research. I'd like to use the micro four thirds camera rather than the bulky Canon...

4. Terrestrial viewing? A separate diagonal that erects... is that all it takes?

I know it's a lot of questions but any help is appreciated.

Ben

luminary (Ben) · #2 22-03-2010, 02:57 PM

OK after more research Ive decided on the following eyepieces that have the common theme of being 1.25 and 2" compatible.

1. TV Ethos 6mm
2. TV Ethos 13mm
3. TV Panoptic 35mm

I think this little set should be all I need for a good while.

Still looking for any input or help on this or any of the other questions.

[1ponders] (Paul) · #3 22-03-2010, 03:31 PM

Hi Ben.

for powering your scope out in the field, especially if you are using a laptop then you would want at least a 35 Ah for a couple of nights if you aren't able to recharge. If at home do away with the batteries and get a regulated 12v 2 - 5 Amp transformer to run you scope.

You can try an off axis guider. some people swear by them, others hate them with a passion. I fall into the second catagory

. Withouth the OAG though you'll either need to go the guidescope route (which means guiderings, counterbalance weights for the bottom of the scope, guide camera, laptop) or a selfguiding camera (ie astrocamera SBIG FLI, Apogee, SX etc)

If you want to do terrestrial viewing, get a scope for that. The FL of the 8" is really too long for much except extreme distance viewing. A nice 60-80mm spotting scope (or normal refractor that can be used for autoguiding) would be nice.

btw starting out imaging through an 8"SCT even with a 6.3 reducer (yes you will need a T ring and T Adapter to go with the FR) will be extremely challenging. Good luck

luminary (Ben) · #4 22-03-2010, 08:39 PM

Quote:

Originally Posted by [1ponders]

Hi Ben.

for powering your scope out in the field, especially if you are using a laptop then you would want at least a 35 Ah for a couple of nights if you aren't able to recharge. If at home do away with the batteries and get a regulated 12v 2 - 5 Amp transformer to run you scope.

Thank you Paul. Can you give me some pointers on where to obtain the 35 Ah batteries and chargers? I'd like to have the option of being untethered. I'm guessing that the regulated transformer would be easy to obtain from somewhere like Jaycar?

Quote:

Originally Posted by [1ponders]

You can try an off axis guider. some people swear by them, others hate them with a passion. I fall into the second catagory

. Withouth the OAG though you'll either need to go the guidescope route (which means guiderings, counterbalance weights for the bottom of the scope, guide camera, laptop) or a selfguiding camera (ie astrocamera SBIG FLI, Apogee, SX etc)

I'll have to think about this a bit more down the track I feel. I'll probably hold off on this aspect till I am more familiar with the scope itself etc. Maybe something in the new year.

Quote:

Originally Posted by [1ponders]

If you want to do terrestrial viewing, get a scope for that. The FL of the 8" is really too long for much except extreme distance viewing. A nice 60-80mm spotting scope (or normal refractor that can be used for autoguiding) would be nice.

I think that's a very reasonable option - though I sold a Kowa a while back after finding I wasn't using it as much as I thought I would. I'll leave this for the future too.

Quote:

Originally Posted by [1ponders]

btw starting out imaging through an 8"SCT even with a 6.3 reducer (yes you will need a T ring and T Adapter to go with the FR) will be extremely challenging. Good luck

Yes I can appreciate this and take it on board. I'll probably leave the imaging till later.

I'm also sobered by the price of the Ethos pair, and after reading reviews I am wanting the 21mm to go with the 13 and the 8mm - and together with a 2" dielectric diagonal that's getting up to $2800!

As much as I paid for the scope!

EDIT: I've just ordered the 21mm and the 13mm Ethos eyepieces; together with the 2" Everbrite diagonal. The 8mm can wait till later.

[1ponders] (Paul) · #5 22-03-2010, 10:40 PM

I picked my battery up from a local battery supplier here on the coast. The also had a container to put it into (plastic but ok) where I could connect to external terminals or plug in a ciggie plug, plus it had a charge indicator on the top. very handy. Battery and suitable charger though aren't cheap. Few hundred $ all up from memory.

Yep jaycar will sell what you need.

Definitely if you are buying ethos stick to the visual for a while

or maybe try some planetary imaging where focal length is an advantage and a wedge isn't needed.

luminary (Ben) · #6 29-03-2010, 08:13 PM

So by sheer coincidence all the items arrived today.

Scope and Ethoses.

Set it up and sneaked a peak at the moon with the included 40mm eyepiece and a very brief look with the 13mm Ethos. Bad seeing conditions with much shimmering at the moon's edges and craters.

I only have one problem now.

When I asked whether the 2" star diagonal would fit onto the CPC I was told yes.

Not so. The scope comes with a 1.25" visual back.

I'm assuming I need a 2" visual back - however my 2" Televue star diagonal has an internal thread and the supplied 1.25" visual back has thumb screws to tighten in the supplied 1.25" diagonal.

What do I need to buy to make the CPC scope marry up to the Televue Everbrite 2" star diagonal?

Sorry that this is probably a very basic question...

[1ponders] (Paul) · #7 29-03-2010, 08:26 PM

That's strange. I don't know the Celestron 8" very well, but surely the 1.25" adapter screws off to show a 2" SC thread that the diagonal will fit?

luminary (Ben) · #8 29-03-2010, 09:33 PM

Quote:

Originally Posted by [1ponders]

That's strange. I don't know the Celestron 8" very well, but surely the 1.25" adapter screws off to show a 2" SC thread that the diagonal will fit?

Thanks Paul.

I think I have found the answer.

http://www.televue.com/engine/Produc...dapter,%20long

This is the adapter that allows the fitting of the 2" star diagonal to the SCT thread on the back of the telescope. It appears that Celestron have discontinued the 2" visual back.

Bintel also has one https://www.bintelshop.com.au/Images/Stock/7404X.jpg

The passover holiday means the New York shops won't deliver till mid April, so Bintel it is...

I wasn't really expecting the 21mm Ethos to arrive tbh...

[1ponders] (Paul) · #9 29-03-2010, 09:43 PM

good luck with it

luminary (Ben) · #10 29-03-2010, 09:47 PM

Quote:

Originally Posted by [1ponders]

good luck with it

Thanks Paul, you've been of great help.

Can't wait till the weekend now...