Celestron C8 bagged! Some advice now please.

[Stormwatch]

I got a Celestron C8 today, with Starbright coatings. The guy that sold me it came to the trouble of bringing it to my house as well, so no postage or petrol costs, perfect.

I've been having a look at it and it has some things I'm curious about.

1)There's a big handle type thing, which we ascertained on here was for piggybacking a camera. How exactly would I do this? There are holes in the "handle", do I need to buy something to screw into the holes and camera base?

2)When I screwed off the visual back there seems to be another screw on lens attached directly to the back of the scope. I looked through it and it just seems to be clear glass, would anyone tell me what this is exactly? It's threaded so would I guess take filters.

3) I want to use my 2" push fit diagonal with the scope and also get a 0.63 focal reducer so what would be the best way to go about this? I'd need a 2" focal reducer, but I'm a bit lost as SCTs have screw in connections and I'll need some sort of adapter. Astro Engineering do a 2" visual back which will take push fit accessories, would that be all I need? Attach the focal reducer to the scope, screw in a AE visual back then either my camera or diagonal?

It's all most confusing when I get a new scope!

And I hold out no hope of getting a shot of it tonight either! On the plus side it came with a hard carry case, a dew shield and an Orion 8 x 50 finder which is massive! The SCT seems to provide "right way up" views though, while the finder shows things upside down, which may be a problem...?????

[John]

1)There's a big handle type thing, which we ascertained on here was for piggybacking a camera. How exactly would I do this? There are holes in the "handle", do I need to buy something to screw into the holes and camera base?

I'm not sure about that one. It's probably what it looks like - a handle that doubles as a camera mount

2)When I screwed off the visual back there seems to be another screw on lens attached directly to the back of the scope. I looked through it and it just seems to be clear glass, would anyone tell me what this is exactly? It's threaded so would I guess take filters.

It's probably a clear filter to keep dust out of the OTA. Not a standard item but a lot of folks use them.

3) I want to use my 2" push fit diagonal with the scope and also get a 0.63 focal reducer so what would be the best way to go about this? I'd need a 2" focal reducer, but I'm a bit lost as SCTs have screw in connections and I'll need some sort of adapter. Astro Engineering do a 2" visual back which will take push fit accessories, would that be all I need? Attach the focal reducer to the scope, screw in a AE visual back then either my camera or diagonal?

If you want to use a 2 inch diagonal with an SCT there are 2 ways to do it, i) fit a 2inch visual back (about £20 to buy) then put a standard push fit diagonal into that or ii) get an SCT screw fit 2inch diagonal which start at about £35. The Celestron / Meade reducers (either will work) cost about £60 used although there is an Antares one which is about this much new. The reducers don't work if you have gone the 2 inch visual back / push fit diagonal route - they seem to need a screw fit diagonal or the standard 1.25 inch visual back / diagonal combination.

I hope the above helps a bit at least. V. Nice scopes the C8's - you will need to keep the collimation good to get the best out of it. If your scope is not already fitted with them, I'd get some "Bob's Knobs" ASAP.

John

[Astroman]

1) The "handle thing" looks like a counter-weight holder to me, but I can't be sure. The bracket at the back could be for piggy-backing cameras. If a screw fits in either bracket or handle, you could use them as needed.

2) That's probably a fringe killer or light pollution filter, if it's thin. If it's thick, it may be a focal reducer. You could plug in an eyepiece and point the scope at something with the screw-in glass installed, then try again with the same ep without it and see if your field of view changes. If so, it's a focal reducer. If not, it's a filter of some kind.

3) 2" diagonals are a waste of money on anything smaller than a 10" scope, imho. The visual back needs to fit the 2" pieces, and I think the FR is also 2". (Mine is.) Other than that opinion, you've got the sequence right.

The view through an SCT is flipped left to right, with north up.

hth

[Stormwatch]

Thanks a lot for the replies all

Here's a couple more pics to help. I think David is right about the filter type, and the "handle" really does look like it probably is just a handle, although it has holes drilled in it all the way along.

[Stormwatch]

handle

[Stormwatch]

3) 2" diagonals are a waste of money on anything smaller than a 10" scope, imho.

I used my 2" diagonal on my lowly 102 SLT refractor and there was a big difference compared to 1.25 EPs, even using the cheap 2" accessories like I was. The field of view using the 2" stuff was great.

[Stormwatch]

About this finder scope I got with the C8. As I say, the images are upside down, while the C8 is right way up (thanks Astroman!). It seems very counter-intuitive to have a finderscope that shows images differently from the way they appear in the scope.

Am I wrong? Does anyone else have a setup like that?

If I were to sell the Orion 8x50 finderscope (big thing!), how much might I get for it, and what would I get to replace it?

[Astroman]

I had the same problem initially with my finder scope and C8 image difference, but once you get used to it, it's ok. You'll learn which way to move the scope when looking through the finder, then through the mains.

AFA 2" EP's go, the central obstruction of the C8 makes a big difference with them as opposed to a refractor. Plus, the long FL of the C8 causes longer EP's to vignette easily. At the other end of magnification, the image actually reaching the EP wastes much of the incoming light, so you don't really gain anything there. As I said though, it's a matter of opinion. I find 1.25" EP's quite sufficient on my C8, but I do plan on adding some 2" for the 10" F/7 in the dome. It all comes down to money, I guess.

[pmlogg]

Stormwatch

I see that your new C8 is fitted with one of the long Celestron rigid dew shields, a Dewstar I think they called it. Are you able to fit the front cap on when it is fitted or do you have to take it off first? I'm interested as I was thinking of buying the shorter version, which seems to be the only one still made.

[Stormwatch]

Stormwatch

I see that your new C8 is fitted with one of the long Celestron rigid dew shields, a Dewstar I think they called it. Are you able to fit the front cap on when it is fitted or do you have to take it off first? I'm interested as I was thinking of buying the shorter version, which seems to be the only one still made.

Do you mean, can I fit the front cap onto the dewshield? No.

Or did you mean can I fit the front cap on THROUGH the dewshield - it's packed up just now in the cupboard but no, I doubt that as the end of the dewshield seems to be slightly smaller than the end of the scope (It tapers).

OR did you mean can the dew shield fit on when the front cap is on the scope? I don't think so, but when I get it out next I'll check.

Is this for storing it? I normally take the OTA off the tripod, and keep it in its case. Then sit the dewshield onto the mount. Means I can fit it all in my wee cupboard under the stairs along with a couple of guitars, an amplifier, a 102 SLT refractor and other bits and bobs!

[pmlogg]

I meant could the cap be fitted onto the end of the dewshield. I suspected that it would not. Thanks for confirming it.

I've just replaced my OMC140 that I kept with its rigid dewshield fitted all the time (no case for it anyway). Its lens cap fitted onto the end of the dewshield as it did onto the OTA. I would like to do the same with my new C8. Also I would prefer to leave a lens cap on during cloud pauses etc. It sounds however as if I would also have to invest in a new lens cap if I bought a rigid dew shield.

I wonder if any other Member knows the outside diameter of the shorter rigid dewshield (model 94019?) to see if there are other commercially available caps that would fit?

[Stormwatch]

I meant could the cap be fitted onto the end of the dewshield. I suspected that it would not. Thanks for confirming it.

I've just replaced my OMC140 that I kept with its rigid dewshield fitted all the time (no case for it anyway). Its lens cap fitted onto the end of the dewshield as it did onto the OTA. I would like to do the same with my new C8. Also I would prefer to leave a lens cap on during cloud pauses etc. It sounds however as if I would also have to invest in a new lens cap if I bought a rigid dew shield.

I wonder if any other Member knows the outside diameter of the shorter rigid dewshield (model 94019?) to see if there are other commercially available caps that would fit?

The dew shield takes like, literally 2 seconds to remove or replace. You could always take it off, put on the lens cap during cloud passes, then reverse the operation when the clouds have gone. Very easy and very fast.

[pmlogg]

That's good advice.

Thanks