Re: Upgrading my equipment #iEXOS-100 #TECHNICAL #ASCOM #astrophotography


Perhaps it will help you figure out what to do, if we spend a moment on the "why's".
You've been told that you need to guide, because the mount's natural periodic error will cause your image to bump around a bit over time, and nobody likes streaky, lumpy stars.  The fix for this is, indeed guiding.  Basically, the guidescope + guide camera + guide software use a guide star as a proxy for the target that your imaging camera is trying to shoot, and in a perfect world, the guiding system sees a change and corrects for it, before the imaging camera notices (and messes up your stars).  
As to what guidescope and guide camera are right for you, well, that gets into a longish post.  The right answer will probably depend on the scope and camera you choose for DSO imaging.  More on that if you want it.
You will need a mount computer, if you want to guide.  Perhaps a laptop, or a Raspberry Pi, or one of the 'appliance' devices.  You'll run either ASCOM or INDI as platforms, and some mix of client astro-software on it.  Things to ask about and decide on.  Your PMC8 mount is flexible and it is unlikely to pose a limitation.  
You probably don't need to guide, if you want to image planets, but you probably will want different scopes for planetary vs Deep Space Objects's.  And perhaps a different camera as well.  The reason for this is that DSO's are usually wide, dim targets usually shot with longer exposures, and planets are tiny, bright targets usually shot with video (lucky imaging).
This leads people to use different scopes for DSO vs planetary, as well as different cameras.  Kinda like screwdrivers - one needs to pick the tool that suits the job.  
So you probably will want a scope with a wider field of view for your DSO's (and guiding), and something with a much longer focal length (and narrower field-of-view) for planets. 
We do have people her that do both here - on iExos100's, and I hope they chip in - but it will probably simplify things if you think of DSO's vs planets as two different problems that likely require different solutions.
Coming back to guiding, do figure out what scope you'd want to use for DSO imaging.  Small refractors are popular, but there are other options.  Once you have that sorted out,  this site can help you work out a guide ratio that meets your needs:
Some say a guide ratio of 1:3 is fine, but I was happier close to 1:2. YMMV.
No, none of this has to do with cables - those are things that come after deciding your imaging resolution vs guiding resolution, the software you will guide with, and the device you will run that software on.  Only after that, do you know what your cable needs are, because those things are what you connect your cables to.  :-)
Hope this helps...
- Bob
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64

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