Re: EXOS 2 GT Payload Capacity

Jeff Snell

Thanks Mark,
I’m sure there are a myriad of factors that are affecting me.  I’m not too frustrated at this point though.  I’ve only tried it the one time.  I’ll give it a go again sometime later in the summer.  As for the comet, I got out last night in the Great Salt Lake and took some wide angle shots with an Irix 15mm f2.4 and my T5i.  Lots of clouds but I got some decent shots.

I’m camping starting this week in a dark sky area and will have my 80mm APO.  Maybe I’ll look that way😆

Have a great one!

On Jul 18, 2020, at 11:00 AM, Mark Christensen <mjcw500@...> wrote:


One thing that is biting you, I am sure, is the focal length of the 8 inch SCT. That is 2000mm compared to (assuming your APO is f/7) 570mm for your APO. That means the imaging results are nearly 4 times more sensitive to the mounts capabilities, irrespective of weight, which I kind of doubt is the issue.  It also means your exposures, because the SCT is an f/10, have to be twice as long, increasing the window of time in which you are vulnerable to problems in the system, atmosphere, you name it.

So I wouldn't just blame the weight capacity of the mount. 2000mm focal length is pushing it for a mount of this class. Some people make it work but most end up frustrated.
It's why people buy things like the Losmandy G11.

Hope you've been imaging the comet with camera lenses and your APO. With a short focal length telephoto with a fast lens all you need is a tripod, even something as short as 85 or 135mm focal length can produce nice pictures of it. And the speed of that type of lens (f/1.4 to f/2.8 typically) make for short exposures.

With the 8 inch SCT all you'll get is the nucleus.


Mark Christensen

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