#0 - do, don't hesitate. It's truly a great book
The reviews of the book said it was very technical, but I think I've been in this long enough to qualify. I did look at his web page and sounds like he's working on another book that would cover Raspberry Pi, NINA, StarTools....and all the stuff that I use. I've gone totally Linux / Pi with my home observatory, the club 16 inch is all on Windows, so I mess a bit with both, but prefer Linux at home. I'll probably buy the book, looks good from the contents page. I can always buy his next one too.
#1 - do, worth the small $ for teh helpful upgrade - get them 25mm long (that's a metric thing, hmmm, how to explain modern measurements to a Yank???) ;-)
I'll look into that. I've seen them and look like a good investment. Metric is fine with me, it's so much easier then what we use. I used it when taking chemistry, so easy!
#2 - I use my Glatter on teh mount - just point it toward a uniform flat surface on the ground - you're going to readjust anyways. If you are using a laser make sure and rotator your Crayford/focuser around to three uniformly spaced points (120 degrees apart) and ensure the dot isn't moving, you may not have your focuser attachment (or focuser) collimated - this is a BIG scope, minor imperfections are amplified - that dot should not move as you rotate the focuser.
I'm pretty confident in our $900 focuser I just added. The GSO focuser that came with the scope is garbage. It probably cost me many of my 100 hours cursing at this thin. Hmm....the floor is a good idea. I'll have to see if this thing will rotate around and point at the floor. I have a bad feeling that may not work, but I'll check - never had to point at the ground so why would I try that? :-)
#6 - it will often look worse in your Tak after it's actually collimated. My advice here, tape over one of the adjustments (usually the top -12 o'clock ones for me) and then make a single very big but precise change (eg: 1/2 turn in or out) on one of them and note what happens. Then try the reverse. Then move it back. Do the same on teh other side. Don't be afraid to make dynamic changes at the start, this will help you dial in the relationship between the changes you're making and what it does to the on-axis coma. Once you've tried each side, then try both - eg: both 4 & 8 o'clock out 1/2 turn and then in 1/2turn (ie: 1 full turn back) to see what it does. You should notice some very clear patterns to the changes. If you don't - call me and we can setup a TeamViewer session.
So leave one of the three locked in place? I did read someone mention that in one of the many searches I've done. Seems like a good idea, then at least one of the bolts will hold the original starting position. I'll add that to my "try this" list. I did make large movement after I released the mirror and tightened all the 'pull' screws to the stop (or close as I dared when they felt tight). Then backed off 2 full turns, centered it all visually in the Tak scope, then found my FL was closer to 3250mm and stars looked marginally better.
#7 - you should be able to get to 8 seconds or so - you might be using too bright a star - a nice, dim open cluster works best - NOT Alnitak ;-) The longer the exposure the more you can remove the atmosphere from the process - same for using a red filter.
I'll try for a dimmer star in a cluster. Part of my problem might be chasing atmosphere in the 2-3 second exposures I'm sure. Yeah, Alnitak wouldn't be ideal, that flame and horse may be distracting!
#8 - good point, the weather here is already awful, if it clouds over again soon I'll know you're sent money and none of us will forgive you
I got lucky with the $900 focuser, we had a week of good skies. Gave up last night and tried my home observatory, but for some odd reason I had horribly high latency on my network so I gave up. Later it cleared up, maybe some moisture dried up in my Wifi USB antenna?
Distorted stars and funky diffraction pattern.
Oh the pain.....stars don't have corners!
If using the DSI method, I'd align the camera so things match up, then try to tighten the bottom right, or loosen the top left of this. But does it change things? Not really. Just drive me closer to seeking new cuss words to add to my vocabulary.