Re: Expected tracking times *Unguided #EXOS2 #TECHNICAL


What temperatures do you want to operate at?  I'm targeting a -15C limit, but realistically will probably wimp out at -10C (SW Ontario).  Operating in the cold is its own subject... 
I have an EXOS2 PMC8 as well.  My scope's FL is 621mm, not as long as yours.  Funny you should mention the 150PDS, because I've had my eye on those.  I love my refractor, but the 150PDS would give me better scale on galaxies.  I'd like to know how you get along with it.
Anyway... you probably didn't get the answer you wanted from Jerry, but he gave you the goods.  On both guided and unguided.  
My mount is well-tuned, and at my FL, I can get 30s reliably, unguided.  That's it.  Guided - if you take care with the adjustments - it can be crazy-good.  More minutes than I can make use of in my light-polluted Ontario skies.  See link below for an eyebrow-raiser.  Strictly a test of capability, but fun.  For real imaging in my murky skies, I have to use 60-180s exposures or I'll just get swamped.
Did I *want* to guide?  No.  I saw it as a complication rather than a solution.  Having done it for a while, I've flipped and now see it as simplifying my imaging rather than complicating it.  It adds reliability that unguided simply didn't have.
I spent a lot of time (too much?) getting down into the weeds on my mount hardware and why it did what it did.  And at one point, Jerry took pains to spell out to me that they optimized the mount for guided, not unguided.  What this means to us is that between the PMC-8, the belt drive, and the guiding software (PHD2 usually), the combination is able to overpower the the mechanical shortcomings of an inexpensive mount and make it punch well above its price point.  I did write up my findings in a tuning doc (link below), so other folks could leverage what I found. As always, YMMV.
My answer to laptop-in-the-cold was to get a refurbished lenovo x230 with win7pro.  Still available, and cheap.  They're mil-spec tested, and all you have to do is keep the battery reasonably warm. I'll be making a foam wrapper for mine for this winter.  I have a Talentcell on order, to run everything else, so I should be good for several hours of autonomous ops in the cold this year.  And if at home, I can remote into it from the warmth of the house.
If you do decide to guide, at 750mm you probably should take care with your guide camera/guidescope FL choices (link below).  I just changed out my guidescope on Jerry's advice and (if seeing permits), can spend most of a session well under 1.0" RMS.  
Hope this helps...
- Bob
Tuning doc link:
900s image post link:
Guidescope calculator link:
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64

Join to automatically receive all group messages.