My new Celestron C6-SGT XLT Goto Schmidt Cassegrain Telescope

Posted by XTSee on 19th January , 2009

After the shennanigans of receiving two of the same telescope, and regrettably having to return one of them back to First Light Optics, I spent the first evening reading through the manuals. There’s no hurry because bad weather is forecast for the next few days, so I’ll just get used to learning about it and putting it together nice and slow.

Celestron C6-SGT-XLT Telescope

Celestron C6-SGT-XLT Telescope

So here it is. It should be noted that mine is not strictly a proper C6-SGT, because I bought the Advanced Series C6-S XLT (non-Goto) in the January sales (£200 off!) and then also ordered a SynScan PRO GOTO Version 3 Upgrade Kit for EQ5 to give the same functionality as the full goto Advanced Series C6-SGT XLT.

Now that I’ve read through the manual, in hindsight it may have been better to pay the additional £100 I saved overall, because although the Synscan upgrade works perfectly well with the Celestron EQ5 mount, the Celestron version of the Goto system seems superior to the Synscan.

There are some slight aesthetic design differences and the functions described in the manual for the Celestron suggest quite a few extras that the Synscan does not have, e.g. both +ve and -ve Backlash settings for RA and Dec (the Synscan has just one value each for RA and Dec), Filter Limits to keep goto within certain RA/Dec co-ordinates, Goto Approach, Calibrate Mount, Polar Align function, Sun menu (prevents the Sun being chosen for safety).

Otherwise most functions are identical or near equivalent.

The object database on the Celestron provides a couple more grouping options, e.g. SAO, Abell, Asterism, CCD Objects.

Overall the scope seems well built, and the assembled scope and EQ5 mount are very sturdy and secure.

The Synscan GOTO is pretty cool the way it does the alignment, and slews around to each star position, before locking on and tracking. I love my XT10i, but with the C6 it feels like I’ve got a “proper” telescope now - there’s something very satisfying about watching the scope move to the required object.

I did a quick finder scope to OTA alignment out of upstairs window to a streetlamp in the middle of the village.

There was a clear sky for a couple of hours last night so I took it out and had my very first attempt at polar alignment, then 3 or 2 star alignment (seems difficult, maybe I’m not getting it right yet), before having a go at sighting up some objects.

First light was on the Beehive, then the Double Cluster. Very nice and smooth to pin sharp focusing despite being a bit of a dull night.

There are a couple of things I’ve yet to understand better!

For instance there are RA/Dec directional keys (of course), for aligning or just repositioning the view.

Well in one direction they will nudge tiny amounts, but in the opposite direction, it slews several minutes/degrees of sky very quickly, then slows down to tiny adjustment again while I hold the key down, then when I release the key it stops, and then hit the opposite direction again it slews the same amount  back again.

A bit wierd and I guess its something to do with taking up “backlash” (which can be adjusted), but I’m not dead sure if this is normal, or only occurs after I’ve done 2-star as opposed to 3-star alignment, or happens when viewing objects in a particular half of the sky?

Oddly the manuals don’t say a thing about this behaviour, and I’m wondering whether I need to upgrade the hand controller and motor firmware?

Tried finding something on Cloudy Nights forum about this auto-reversing when pressing the direction keys, but couldn’t and wondered whether I just wasn’t searching for the right thing.

Oh well - shall see in due course. [Update: read a later post about upgrading the Synscan firmware to fix a problem]

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5 Responses to “My new Celestron C6-SGT XLT Goto Schmidt Cassegrain Telescope”

  1. Synscan PRO Goto Backlash problem | Jims Orion XT10 Astronomy Blog

    [...] my previous post about my new Celestron C6-S telescope, which I upgraded to Goto using the SynScan PRO Version 3 Goto Upgrade Kit for EQ5 I mentioned that [...]

  2. Arnaud Marie (1 comments)

    Dear sir,

    Very nice review about the Celestron C6-S XLT. I live in France and I would be very happy to buy such a good telescope at the UK Price (about 342 £)

    The local importer MEDAS and Celestron doesn’t allow us to buy directly from UK and the local price for this telescope is way too high here in France ( 750 Euro for OTA and 1300Euro for the Goto version). They also do not sell the non-goto version !

    I would be very interested in buying this package with the help of a UK resident who could buy it directly to First Light Optics and send it to me by a carrier.

    Please let me no if it could be possible.

    It’s a very serious demand, really !

    Arnaud Marie
    Rennes (35)

    You could join me with private email :

  3. Andy (2 comments)

    Very nice review about the Celestron C6-S XLT. I live in France and I would be very happy to buy such a good telescope at the UK Price (about 342 £)

    thank you

  4. XTSee (25 comments)

    Andy, as you can see this same situation occurred with the previous commenter. Although I tried to help Arnaud, there were various cost/payment, shipping and customs & excise issues which made things very difficult, and we had to abandon the idea.

  5. Mark (2 comments)

    This seemed more like a review of the mount with very little info on the scope. I to have been looking for reviews on C6-SGT and haven’t found much on the web.

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