To sell the C8 for a refractor or not to sell the

Hi Everyone,

My name is Matt and I live just outside Pittsburgh and own a C8s-GT on the CG-5 mount. I am only interested in Astrophotography and recently wanted a refractor setup. I have a potential buyer for my C8 for 775$ and I am not sure if I will regret selling the C8 and buying an APO. Seeing the pictures people post are just tremendous and I want to get those pinpoint widefield shots. Budget wise I am looking at, after selling the C8, around 1500$ give or take 100$.
If I decide to do that, what are some possible refractors I should look at? I will also want a guide scope and DSI pro to guide with so please take that into account.

Thanks for reading,

Matt

So you are just selling the C8 OTA and keeping the mount
for the refractor, right?

I take it you have done some photography with the C8.

Hi Matt,
I use an William Optics 80mm APO f/6 for imagining and it works very well. It is lightweight, which is always a good thing and it has a nice wide field, which is also a good thing for photography. You can get an 80mm APO for the price you wish to pay.
Keeping the weight down will really help with the mount, it will not shake as much or be overloaded.
The 8" SCT will take good photos, but is very narrow in field, the worst problem. It is also going to make mount PE more and more apparent due to this. The light grasp is good though and on objects that are not too large, it will take a good shot.
A very light 60-80mm scope for guiding would be good, it would even be possible to guide with a 50mm finder, but not as easy to set it up. Keep the guide scope as light as you can, it does not have to be an expensive scope.

Matthew Dieterich said:

Hi Everyone,

My name is Matt and I live just outside Pittsburgh and own a C8s-GT on the CG-5 mount. I am only interested in Astrophotography and recently wanted a refractor setup. I have a potential buyer for my C8 for 775$ and I am not sure if I will regret selling the C8 and buying an APO. Seeing the pictures people post are just tremendous and I want to get those pinpoint widefield shots. Budget wise I am looking at, after selling the C8, around 1500$ give or take 100$.
If I decide to do that, what are some possible refractors I should look at? I will also want a guide scope and DSI pro to guide with so please take that into account.

Thanks for reading,

Matt

Depends. If you don't do any serious visual work, you MAY NOT miss the aperture. A smaller APO is much easier to handle when getting going with imaging due to its wider field and less critical need for precise guiding.

Unless you are using a big chip camera, however, the C8, especially one with an f/6.3 reducer, will deliver excellent small stars to the frame edge. I know mine does with my Canon 400D. I like and use small APOs for imaging, but I would never let go my C8. It's just too versatile and that aperture packs a punch when I need it for visual _or_ imaging (you may tire of wide field and want some detailed shots of medium-small objects).

My advice? Keep the C8 and get a William Optics 66 ED. it will bring a lot of the benefits of the refractor--I've taken some amazing widefield shots with mine. It can also serve as a guide scope for the C8 (or the C8 can play guide scope for it).

8)

I think that, all told, I would pick an FS128 as a general purpose instrument over a c8, or an equivalent or better triplet apo such as the TOA 130.

The approximate cost is 3x more. I don't think I would pick a four inch apo over a c8, but a four inch apo is a nice thing to have.

But the mechanical advantage of the SCT will be evident if you keep the same mount. A five inch refractor is much more demanding of the mount than an 8" SCT. For a good optical trade off--the aperture of the C8 for the wider field of view of the refractor, I consider that a reasonable trade if the refractor is a 5" and f/8 or faster. So optically 5" apo is >or=a good c8 (for general purposes where wide field is viewed as compensation for less light gathering).

Mechanically a 4" apo = a c8. You'll have to step down to 4" or less if you want the mount to be as steady as you are used to, an important consideration if imaging. This is also true of portability. The FS128 is much more hassle to transport than a c8. To get C8ish portability, the refractor has to be about a 4" f/6.

A four inch apo (from China) will come in a tad more than an XLT c8, by $100 or $150. The real good triplets will run 3x the price.

regards Greg N

Matthew, not sure if I would "replace" a C8 with a 4" refractor, but I would try to "complement it"... as they are both completely different, and they each have their strenghts and weaknesses...

Matt
I agree with those recommending the 66mm to 80mm APO's. You plan to use the CG-5, which is a good, but not a great imaging mount, so the a lighter, shorter focal length refractors will be more forgiving of guiding errors and still produce nice images.

I started my imaging with the Tak FS-78 and can recommend it as a great start, especially with the focal reducer. And if you still take a visual peak through it, it won't let you down there either. When matched with an HA narrowband filter, and a good greyscale imager, there are a lot of Nebula targets that fit nicely and can be imaged in spite of city lights.

Have fun.
Steven Jindra