Quote:
Originally Posted by astronobob
Very Fine result Marc, grouse going on picking the right night aswell, reckon that is half the challenge of astroimaging !
You are guiding with an Off-Axis if memory serves, if so, hows finding stars with a little pick-off and F10'ish ? ?
I'm going down this road soon  
Looks like you have it rather sorted 
Rgrds |
Hi Bob, thanks for the feedback.
I've attached some pics of the backend so you can see how everything is bolted on and the approximate distance from the camera from the back of the primary cell. On the front you can just make up the pickup prism at the bottom of the field in focus, right in front of the Ha filter.
I also use a Sharskypro kit for focusing so I move the primary up and down. The focuser is not the original. I've replaced it with a 10:1 micro focuser from Starizona. A must for any SCT IMHO.
To successfully guide at that FL you'll need to collimate your scope pretty well if you want to get a guide star with a decent shape unless your SCT is ACF.
I guide with PHD, the old version. I don't use PHD2. Don't fret if you see your graph going up and down, given the image scale you're still guiding well within ball park.
I think my calibration steps are 200ms so I get 10 steps for each. W E N and S. Other than that settings are default.
Your guiding will be determined by seeing conditions. Pick your night. Unless your seeing is good to exceptional don't even bother. Also no wind is a requirement. Obviously
Lastly refrain from walking around your scope or even touching it while it's guiding. It will show in your guide graph and photo.
To find a guide star bright enough can be challenging but if your guider is focussed accurately, not impossible. The guider chip being so small on the lodestar I first do a couple of test unguided exposures on the main camera to see if my DSO is inside the fov. 1min or 2min. My FOV is pretty tight and my goto is not that accurate so I do a bit of fishing to find my targets unless it's very bright like M8 (go M8!). My fov is about 24'x18' at an image scale of 0.4 asp. So that's probably even tighter than my polar alignment accuracy.
So once you've got your framing ok you move your scope W,E,S and N slightly and look for anything zooming by the small FOV of your guider. That's how you fish.
It's likely your framing won't be changing much by offsetting the fov of your guider.
Unless you're one of the superdoopa skyX users with plate solving, robotic mounts, remote operated rigs on top of distant mountains and you do everything by the numbers and land on it day after day, that's how I'd do it.