Celestron Edge HD 8 "

[Gan]

I am pretty sure this topic is not new in the forum, but I was unable to find anwers for my problem.

When I bought my Celestron the seller recommended Celestron Off Axis Guide and QHY5L II for astrophotography. My interest is in taking good photos of nebulae.

I am a beginner and I find it very difficult to get my head round how to use the autoguider for better tracking.  In fact I am not even able to capture a single star ( using PHD software) so far. I contacted my seller who insists that OAG is the best with SCT scopes ( as opposed to finderscope) for using autoguider in view of long focal lengths ( 1000), and he argues that to get a good effect with a finderscope autoguding I would need at least half the focal length of the main scope which means a very long and heavy finderscope/guide scope.

As you can see I am a bit lost and would be very grateful for help and direction from experts. Please help

[Leveye]

I use a very inexpensive Zhumell 9x50 162mm scope with a Meade DSI1 mono camera with my C8 and it works great autoguiding with it.

[Luke]

I haven't done DSO imaging for a while but I did some imaging with a C11. I tried with an ST80 guide scope (very light) and that was sort of okay but often I had problems guiding. Things got better when I switched to an off axis guider.

So my conclusion would be, it can be done with a short guide scope, but personally I would go for off axis guider for an SCT, it can rule out a bunch of potential issues.

That said, an SCT and guide scope is not the easiest setup to tame, and even more so an SCT and off axis guider. I am glad that I had some imaging experience behind me before I tried it, I would not recommend it as a starter setup generally unless you feel confident and like a challenge.

Are you using the 0.7x reducer? At F10 prime focus again it will be that bit tougher...

IF funds allow, I would consider getting something like an ED80 scope and get going with that, you can return to the SCT later and that might be handy for sneaking in closer on objects.

As you want to image nebulae, there are some fabulous targets for an ED80, I would have started there rather than with an SCT personally.

I hope that does not sound negative, it can be done with the SCT so please don't let me put you off, I just think it's worth considering easing in with something considerably easier to start with if that allows.

Perhaps time to take a step back? I'd suggest reading the book for a good imaging grounding:

Making Every Photon Count

http://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

If you are determined that no you need to get the Edge going, is there is anyone local that can help you get it going at a local club?

I do have an Edge 8 but no longer image DSO's, I use mine for lunar observing and imaging mostly.

[PhotoGav]

Hi, I'm not sure you are going to like my answer, but I feel compelled to respond!

Your seller is absolutely right, the best way to guide the EdgeHD 8" is with an off axis guider and the QHY will do the job. However, if you are interested in imaging nebulae, then the edge isn't really the most suitable telescope... It's field of view is very narrow (unless you are using Hyperstar, but I can't believe you are given the OAG discussion) and the majority of nebulae are pretty big, so a wide field of view would be most appropriate. Unless of course you are trying to image tight details within a nebula. The advantage of a scope with a wider field of view is that it is also much easier to guide, probably with a finder scope modification and plenty of guide stars to choose from.

So, unless I have misunderstood, your intended imaging targets would be better suited to a different set up completely! You might go back to the seller and discuss this?

What other gear are you using - mount, camera?

I hope that this can help.

[gnomus]

I bought an Edge HD8 with the intention of using it for visual, and 'perhaps' to get into imaging. I was able to guide using a camera attached to the finderscope. I was able to get some results, though none were great. It became clear that many of the 'usual targets' were simply too large to fit in the field of view of the Edge. Things became much easier when I got the ED80. I now use the ED80 for DSO imaging. (Even then some targets are a bit of a squeeze.). I use the Edge HD for lunar and planetary imaging, and for visual.

[Owmuchonomy]

As above, your set up is not really suitable for anything but the smaller objects. Your dealer is correct about OAG being the way to go for your scope of fl 2m. At long focal lengths and F10 it will be a struggle to guide succesfully. I'm not familiar with that guide camera but sensitivity will be paramount to capture a decent star field. I've used my Lodestar to guide my 9.25" and it works to a point.

[PhotoGav]

Thought I would add a bit of a plug for the Edge as well....

I bought an EdgeHD 800 last year specifically for the long focal length with a view to imaging galaxies and some of the smaller targets. It is good, though slow, for that purpose. It is a bit of a beast to guide, but I can get 1800s subs with 'no problem'. I use a Lodestar X2 guidecam and it hasn't let me down yet. I was imaging M82 last night and struggled to find a guide star, but with a bit of reframing I found one very faint dot and proceeded to guide 1200s subs on pretty much thin air!

So, while perhaps not the perfect scope for The Heart Nebula or The Andromeda Galaxy, the EdgeHD does have its niche in the kit bag. Don't forget, you can never have too much astro gear!!!

[Geordie mc]

Have you tried centring a bright star such as Sirius in the scope and seeing if that appears in PhD through your guide cam/OAG? If it doesn't then you may need to align your OAGs pick off prism to make sure it's in the light path. I know it's more expense, but the new lodestar x2 is a very sensitive guide cam and might help. As others have said, and I'm an Edge owner myself, it's not really a good scope for large DSOs. An80 mm refractor would be better or even smaller. There are some very nice 65-70mm scopes out there. The Edge is however great for Lunar and planetary îmaging and observing.