Telescope advice - Celestron C8-SGT

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Dr Bob
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Telescope advice - Celestron C8-SGT

Post by Dr Bob »

Hello PopAstro

I have spent some time researching a good telescope I can grow with and have landed around the Celestron C8-SGT.
My main considerations have been portability, ease of use and suitability for photography.

I was hoping if anyone has one of these fine telescopes (or not!) if they could advise:

1. Are there any other good choices out there for a similar budget?
2. What accessories would be advisable from the start - e.g. dew shields, power supplies...? and what could wait....

Any thoughts very much appreciated,
Rob
David Frydman
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Post by David Frydman »

Welcome Rob,

I used a C8 many years ago but don't know the current models.

Rachel using the name The Bat has a C8 S XLT so maybe she can advise.
There are also others who will be able to help.

There are 2 main makes the Celestron 8 inch SCT and similar models from Meade. There are also other makes of similar scopes.

Hopefully someone will advise.

regards, David
The Bat
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Post by The Bat »

Hello, Rob, and welcome!

David is right. I have a Celestron C8, although mine is not the Go-To version. I can assure you it will be an excellent telescope. I chose the C8 based on the good reviews, the good reputation of Celestron and the design and portability of the Schmidt-Cassegrain.

On the plus side, the optics are great. At star parties I have attended with my society, people often compliment me on the view through my scope compared to some others. It delivers great views of the planets, the Moon and deep sky objects.

If I had to pick out a bad point, I would say that the long focal length can be problematic for some applications. Large objects such as the Pleiades and Beehive Cluster are too big to fit in the field of view. These objects look best at lower powers than you can achieve with this instrument without some sort of wide field eyepiece. The higher power will mean some deep sky objects will look dimmer compared to a reflector of the same aperture and shorter focal length. The long focal length is great for planetary viewing and imaging, but not ideal for long exposure deep sky imaging. You have to use longer exposures to get the same image with this f10 scope as you would with a telescope with a focal ratio of f4-6, say. That's not to say you can't image with it. The Go-To version has a port for guiding, so you at least have the option to upgrade your imaging kit with a guidescope later on, which will allow you to take deep sky photos. There is also a gadget (Hyperstar, I think it was called), which you can substitute the secondary mirror for to convert it to a faster scope for astrophotography.

I'll admit I have struggled to take deep sky images with mine, but I don't have the Go-To and guiding functionality. The long focal length is not very forgiving of polar alignment inaccuracies and long exposure imaging will be a challenge unless you have some sort of guider.

The CG-5 is a fairly sturdy mount. Not as hefty as the HEQ6, for example, if you're planning on imaging, but adequate. I can't comment on the ease of use of the Go-To system, but I was a complete novice when I bought my scope and it didn't take long to get to grips with.

In terms of accessories, a dew shield is an absolute must or you will find dew and frost curtail your viewing very quickly. A flexible one is much cheaper and easier to use and pack away than a rigid one. A power tank is fairly essential to power your motors and Go-To. If it's like my scope, it only came with one 25mm eyepiece, so if your budget allows I would get a decent 2 x Barlow and a low power eyepiece such as a 32mm Plossl. Mine also did not come with a polar alignment scope (fits in the mount's polar axis). If you are going to be imaging, it is something you will need; less essential if you are just doing visual observation.

There is no such thing as an all-round telescope, but it comes pretty close in my book. If general viewing and planetary imaging is for you, this is a great scope. If deep sky imaging is your priority, you may want to re-think because a fast reflector may be a better choice - and the tube will be cheaper allowing investment in a more sturdy imaging mount. An 8" reflector is considerably bigger though, so it depends on your definition of 'portable'. :D All scopes have their good and bad points so it comes down to you knowing exactly what you want to do with it.

Hope that helps.

Rachel
Celestron C8-S XLT
CG5 mount, dual axis motor driven
Imaging Source DFK21AF04.AS camera
North Essex Astronomical Society
Dr Bob
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Post by Dr Bob »

Many thanks to you both your comments.

It's great to hear such positive views, and I feel a purchase coming on!
brian livesey
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Post by brian livesey »

Hi Bob, Just to say that a rolled, foam, camping mat makes a good dew shield for a C8, and there's no weight penalty with it.
Make the shield protrude three times the diameter of the scope.
Make sure to line the inside of the shield with black, absorbent, material such as blotting paper ( pre-blackened with ink ) or felt.
brian
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