This is stellar work! (Pun intended)
I'm going to have to look through your other posts for more inspiration. I too love astrophotography. I've got a Meade LXD55 SN-6, which has a 762mm focal length and 6 inch "aperture". I've got a mount that allows me to track the night sky as well, although I've never installed batteries and tried that yet.
I see you say it takes you 45-90 minutes to polar align your scope. I would love to read more about your process doing this. If you've already discussed it in the past a link to that information is perfectly fine, you don't have to rewrite it just for me.
My "Mount Everest" of astrophotography is the Andromeda Galaxy. Using the same techniques you've described here: polar align, a Barlow to install the camera using prime focus, I was thinking ~45-second exposures stacked using DSS, dark frames to remove noise from hot pixels, and final touch up edits done in PS.
Based on your experience, what kind of results do you think I can expect from this telescope. I still have a lot of practice to do before I attempt to create this image. I would like to get something that is print worthy to put on my wall one day. In my gallery you can see a moon shot I created using this telescope, a 2x Barlow and a Canon 40D. The moon did not fit in the entire frame (crop body and a 2x Barlow), so that image is actually 7 frames stitched together in PS. It came out quite nice in an 8"x8" print; I'm considering printing it at 24"x24" or even as large as 36"x36". I am especially fond of the terminator in this shot, with some craters disappearing into the shadow and the rim reappearing. That I was able to get it this sharp without using a shutter remote is amazing to me.
Again, that's quite a beautiful image you have created. Thank you for sharing; I can't wait to peruse your other work. Keep 'em coming!
Thanks very much. Set up and alignment are critical for long exposure work. It's important to level your tripod/mount, balance all of your gear on the mount(including the camera) and of course polar align accurately. Leveling is simple(be sure to set up on a sold surface or leg blocks to avoid sinking), balancing your scope/camera on both axis' is easy with practice but you should read up on it to become well versed and maybe have notes or a print out handy when starting out. Polar alignment will go quicker with practice as well. For even more accuracy you'll want to learn how to drift align. I can get polar aligned(roughly) within 15-20 minutes but drift alignment adds about 30-45 minutes to that but once you've got a clear understanding of the process it'll take more like 20-30 minutes. Google "telescope drift alignment" and you'll find tutorials. I like to stress that fine tuning alignment is critical to long exposure but balancing your gear is also huge in the way your mount will behave during those exposures. There are a series of check points throughout the astrophotography process that need to be addressed to achieve the best results, skip any of them and the results will suffer to some degree and the frustration will increase.
Batteries will work fine for your mount but you might consider a Batter Pack jump start unit to power the mount. You'll also need to be thinking about dew and/or frost collecting on the corrector plate of the LXD55 SN. I also live in the southeast and humidity most months is brutal as you know so dew will shut you down if you don't plan to prevent it. I use a dew heater unit(Thousand Oaks) and dew strap(Kendrick) to keep my optics dew free. I travel to darker skies so the last thing I want is fogged optics or loss of power so I go well prepared. I power my mount with a marine battery and my dew heater with a jump start batter unit. I don't like to have both connected to one source since the dew heater unit runs in cycles which can affect the mount motors and interfere with smooth tracking. I realize this stuff costs money but this hobby is not for the faint of wallet, if you're determined to be equipped to get images worthy of framing. You can always look to buy used gear that's been well taken care of and save quite a bit.
For deep sky/long exposure work I would not be using a 2x Barlow with your scope unless you're after some very small objects like planetary nebula and globular star clusters for example. 762mm on the LXD55 mount is about all any beginner should want to take on for long exposure imaging. Staying at your native f/5 will work in your favor as well. With practice of the above mentioned requirements you should be able to get between 1 and 2 minute exposures with your gear. I would shoot at ISO 800 in the warm season and short some at 1600 during the cold months. I would think that the 40D would handle 800 best. I've used my 20D for the majority of the work in my gallery below. I used the 5D for the Heart Nebula, the Seagull Nebula and a few others. I shoot with three different scopes, 355mm, 500mm and 800mm. My mount is capable of carrying larger scopes but I've accepted these focal lengths as the comfort zone for my mount and for keeping my sanity. The higher the magnification the more tracking accuracy you'll need and that equals more expense and more frustration if you're not equipped to work at high focal lengths.
Processin/stacking exposures is another one of the great challenges of this hobby. I won't go into that now but you should plan on researching that and prepare yourself for learning how to get the most from your hard night's work. Keep in mind I didn't start out shooting images like the ones in my gallery. It took perseverance, patience and a decent financial investment to overcome the challenges. I still consider myself an amateur and student after 13 years. I don't see myself spending more but do aspire to improve on the images in my collection and add those objects I've yet to attempt.
I hope this helps in some way. Good luck and remember start slow to find out if this is a true passion worthy of the investment. I found it to be a pretty slippery slope but not everyone will. It's certainly been an education in optics and the universe, which for me is priceless.