Pros & Cons

[Bino Pete]

Last one I promise!

What are your thoughts on this scope?

http://www.firstlightoptics.com/cpc-gps-series/celestron-cpc-800-gps-xlt.html

A couple of pound outside my budget (I'll have to sell my golf clubs as well as my kayak now) but I think it looks really nice (that's a newbie term).

pros and cons please.

[Peter Drew]

Main pro is that it is a nice stable fork arrangement, the main con is that it is relatively heavy as it is a complete OTA/mount assembly.

[Bino Pete]

Just now, Peter Drew said:

Main pro is that it is a nice stable fork arrangement, the main con is that it is relatively heavy as it is a complete OTA/mount assembly.

Is it a good quality tripod and mount for stable views?

[brantuk]

The mount and tripod are rock solid - I had the 800 and now have the 925 - both absolutely fabulous scopes and if you're going for a fork arm then it's much better to have two forks than a single one. But like Peter says - you need to be strong and healthy to lift them around.

One fabulous feature is the GPS and star alignment - you just switch on wait a few mins - then align any two or three bright stars and you're ready to go. Don't even need to know which stars you're looking at once it has your location locked in from passing satellites.

[Bino Pete]

7 minutes ago, brantuk said:

The mount and tripod are rock solid - I had the 800 and now have the 925 - both absolutely fabulous scopes and if you're going for a fork arm then it's much better to have two forks than a single one. But like Peter says - you need to be strong and healthy to lift them around.

One fabulous feature is the GPS and star alignment - you just switch on wait a few mins - then align any two or three bright stars and you're ready to go. Don't even need to know which stars you're looking at once it has your location locked in from passing satellites.

Did you find any negatives with this scope (apart from the weight) eg. Did it loose collimating etc.

[brantuk]

I never had to collimate either of them Pete - they hold it very well cos the secondary is mounted on the corrector plate and doesn't budge. As opposed to free floating on a spider in newtonians. I always do a star test every time I start a session with any scope and the cpc's just never need adjusting. However - if imaging and/or messing with "farstar" systems, I think it may be a different story.

I always said - if I had to get rid of all my scopes and keep only one - it would be the cpc. They just cover so many bases - jack of all trades type of scope.

[Bino Pete]

6 minutes ago, brantuk said:

I never had to collimate either of them Pete - they hold it very well cos the secondary is mounted on the corrector plate and doesn't budge. As opposed to free floating on a spider in newtonians. I always do a star test every time I start a session with any scope and the cpc's just never need adjusting. However - if imaging and/or messing with "farstar" systems, I think it may be a different story.

I always said - if I had to get rid of all my scopes and keep only one - it would be the cpc. They just cover so many bases - jack of all trades type of scope.

What's the 8" like on dso's and would you say my eyepieces are ok for this scope?

[brantuk]

The X-Cel's will work fine on the 800. I'll never forget my first dso views with the supplied 40mm - Christmas Tree cluster was like diamonds on black velvet. I only upgraded cos the 925 is optimised for photography (though I never got round to using it for that).

[Bino Pete]

19 minutes ago, brantuk said:

The X-Cel's will work fine on the 800. I'll never forget my first dso views with the supplied 40mm - Christmas Tree cluster was like diamonds on black velvet. I only upgraded cos the 925 is optimised for photography (though I never got round to using it for that).

I know this is a stupid question but what differences will I see between my nexstar 127SLT and this 8" CPC?

[Commanderfish]

I've got the C9.25 and very much enjoy it.  Great light gathering, only about 9.5KG for the tube. Very good optics (supposed to be a little better than the C8 and C11), no coma, holds collimation (I've never had to collimate it in the year I've owned it, and that includes trips to dark sites in a Geoptics bag).   

Downsides are that stars won't be as sharp as in a triplet apo refractor - but no scope is as sharp as a triplet apo refractor, and that the field of view is narrow due to the 2350mm long focal length (maxes out a little over one degree TFOV).

[brantuk]

I remember the 800 as just a tiny tad sharper than the 925 on dso's but really nothing to shout about - it may even have just been differences in the seeing or the location. The 800 gathers a lot more light of course and so can see deeper into space than the 127. But it excels on planets, and the moon is just awesome with binoviewers. You wouldn't be disappointed with either 800 or 925 - try get a gander through one at your next obs session or star party.

[Bino Pete]

For anyone who has this scope - 

It is meant to come with a power lead that plugs into a powertank - how long and what quality is this lead?

I only ask because last week I purchased a 5m lead for my mak  and if the supplied one is of equal length and quality I can get a refund on mine.

[Commanderfish]

6 hours ago, Bino Pete said:

I know this is a stupid question but what differences will I see between my nexstar 127SLT and this 8" CPC?

You're looking at 3" of extra aperture which is a lot. Fainter objects will become visible when they weren't before.  This means that each cluster or star field suddenly has a lot more stars in it, and fainter objects like galaxies become visible where they just were not before.  This leads to aperture fever which is why some people end up with big dobs (the easiest way to get big aperture, though not nearly as compact as an SCT).  

Also, the focal length is going to be much longer, so each of your existing eyepieces will produce a lot more magnification, so better for globs, planetary detail (provided the seeing is up to it) and splitting double stars.  This means that your field of view will be narrower for each eyepiece, so you'll probably want to invest in a nice 2" wide field eyepiece, which will mean shelling out a little extra for a 2" visual back for the new scope (plus a 2" diagonal if you don't already have one. 

[Bino Pete]

24 minutes ago, Commanderfish said:

You're looking at 3" of extra aperture which is a lot. Fainter objects will become visible when they weren't before.  This means that each cluster or star field suddenly has a lot more stars in it, and fainter objects like galaxies become visible where they just were not before.  This leads to aperture fever which is why some people end up with big dobs (the easiest way to get big aperture, though not nearly as compact as an SCT).  

Also, the focal length is going to be much longer, so each of your existing eyepieces will produce a lot more magnification, so better for globs, planetary detail (provided the seeing is up to it) and splitting double stars.  This means that your field of view will be narrower for each eyepiece, so you'll probably want to invest in a nice 2" wide field eyepiece, which will mean shelling out a little extra for a 2" visual back for the new scope (plus a 2" diagonal if you don't already have one. 

Can you post a link for the visual back adaptor so I can use a 2" diagonal please.

[brantuk]

Some folks like these:

https://www.firstlightoptics.com/adapters/baader-click-lock-2-for-celestron-meade-sct.html

I use this:

https://www.harrisontelescopes.co.uk/acatalog/Celestron_XLT_Mirror_Diagonal_SCT_2_.html

Or there's this:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p590_Adapter--SC-innen---2--innen---2--Zubehoer-an-SC-Anschlu-.html

And a variety of other brands/models. If you go this route then go for brass compression ring fittings every time - won't mar your eyepiece barrels.

There's a discussion here:

 

[Bino Pete]

10 hours ago, brantuk said:

Some folks like these:

https://www.firstlightoptics.com/adapters/baader-click-lock-2-for-celestron-meade-sct.html

I use this:

https://www.harrisontelescopes.co.uk/acatalog/Celestron_XLT_Mirror_Diagonal_SCT_2_.html

Or there's this:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p590_Adapter--SC-innen---2--innen---2--Zubehoer-an-SC-Anschlu-.html

And a variety of other brands/models. If you go this route then go for brass compression ring fittings every time - won't mar your eyepiece barrels.

There's a discussion here:

 

Would you say the 2" upgrade as essential?

and are there any negatives with the upgrade?

[brantuk]

I never came across any negatives upgrading the visual back to 2". But the two big pluses are: slightly brighter and more contrasty views from the extra light coming through the visual back, and bulkier more substantial eyepieces can be supported by 2" accessories like the 2" diagonals. It also provides a more solid mounting point for cameras, oag's, filter wheels, binoviewers etc.

Yes I would say - whilst not essential - the benefits totally outweigh using 1.25" accessories which are small, fiddly, light limiting, and awkward to use in the dark. You can use a large scope with smaller accessories of course - but life's so much easier with 2" ones.

[Bino Pete]

1 hour ago, brantuk said:

I never came across any negatives upgrading the visual back to 2". But the two big pluses are: slightly brighter and more contrasty views from the extra light coming through the visual back, and bulkier more substantial eyepieces can be supported by 2" accessories like the 2" diagonals. It also provides a more solid mounting point for cameras, oag's, filter wheels, binoviewers etc.

Yes I would say - whilst not essential - the benefits totally outweigh using 1.25" accessories which are small, fiddly, light limiting, and awkward to use in the dark. You can use a large scope with smaller accessories of course - but life's so much easier with 2" ones.

The XLT mirror diagonal that you say you use does that come with a visual back built in?

[brantuk]

The visual back on my 925 is threaded for 2" diagonals which have the Sct adaptor ring on the front barrel (so was the 800). If you zoom into this picture you can see it quite clearly on the right hand side.

http://www.rothervalleyoptics.co.uk/celestron-2-xlt-diagonal-sct-fit.html

 

[Bino Pete]

9 minutes ago, brantuk said:

The visual back on my 925 is threaded for 2" diagonals which have the Sct adaptor ring on the front barrel (so was the 800). If you zoom into this picture you can see it quite clearly on the right hand side.

http://www.rothervalleyoptics.co.uk/celestron-2-xlt-diagonal-sct-fit.html

 

So if I bought this diagonal, that's all I would need apart from 2" eyepieces?

[cloudsweeper]

6 minutes ago, Bino Pete said:

So if I bought this diagonal, that's all I would need apart from 2" eyepieces?

If it's anything like my 8SE you just screw the 2 inch diagonal onto the tube (having removed the VB), then use 2 inch EPs.  My Revelation diagonal came with an adaptor so you can easily switch over to 1.25 inch EPs.  All very straightforward!

Doug.

[brantuk]

Yup - as Doug says - the scope comes with a 1.25" visual back screwed onto it. You just unscrew, take it off, then screw the new 2" diag onto it and commence using 2" (or 1.25") eyepieces. If you are doing prime focus photoraphy - then you would replace the 1.25" visual back with a 2" visual back and add your imaging accessories (typically T-threaded).

[Bino Pete]

4 hours ago, brantuk said:

Yup - as Doug says - the scope comes with a 1.25" visual back screwed onto it. You just unscrew, take it off, then screw the new 2" diag onto it and commence using 2" (or 1.25") eyepieces. If you are doing prime focus photoraphy - then you would replace the 1.25" visual back with a 2" visual back and add your imaging accessories (typically T-threaded).

Once I sell (if I sell) my Mak I will buy one of these diagonals.

I will only be able to afford one 2" eyepiece - any recommendations? I've been looking at these two (are they any good?)

http://www.rothervalleyoptics.co.uk/baader-aspheric-2-eyepieces.html

http://www.rothervalleyoptics.co.uk/20964.html

What focal length would be best if you only had one??

**On a side note - With my Mak, I had to weigh the tripod down with a bag of sand to try and help stabilize it - Do I need this with my new scope? 

[brantuk]

You definitely won't need any extra weights with the 800 nor 925 - they are plenty heavy enough believe me - and rock solid stable. The tripod is the same for both - proper steel 2" dia legs and mount top plate that screw onto the underside of the scope with three good bolts.

As for the eyepieces - I've not used either of those - you need to know what magnification you'll be happy with before picking a make/model. Both scopes are over 2 meters focal length. If I could only have a single eyepiece - I'd have a Baader zoom - but I know that's cheating lol

[Bino Pete]

3 minutes ago, brantuk said:

You definitely won't need any extra weights with the 800 nor 925 - they are plenty heavy enough believe me - and rock solid stable. The tripod is the same for both - proper steel 2" dia legs and mount top plate that screw onto the underside of the scope with three good bolts.

As for the eyepieces - I've not used either of those - you need to know what magnification you'll be happy with before picking a make/model. Both scopes are over 2 meters focal length. If I could only have a single eyepiece - I'd have a Baader zoom - but I know that's cheating lol

I've looked at the Baader zooms - it says the one eyepiece is both 1.25 and 2" - is it a 1.25" with a 2" adaptor or the other way round? Are zoom eyepieces a good eyepiece in general though?