Mounting camera on SCT

[johncneal]

Hi folks, bit a dumb newbie question I'm afraid.

To my complete amazement my first attempt at deep sky imaging (a simple 30s exposure of M81) , after a bit of post processing, gave me a recognizable image. 

It was clear however that longer exposure was required and I started to ponder whether I could simply take further exposures on subsequent nights and then stack these. I'd read around the subject a bit and this seems to be a common technique particularly if you are doing multiple RGB and luminance exposures and combining these.

BUT then a thought hit me. For my first attempt, I'd simply taken the diagonal off the back of the Celestron EdgeHD, fitted the t-mount to my Nikon, and screwed that to the visual back with the EdgeHD T-Mount extender. HOWEVER, I hadn't paid any attention to the exact position in which I'd left the camera relative to scope. So it seems to me if I were to repeat this setup, its likely the camera sensor/frame may not be oriented exactly the same way relative tot he scope as the previous images. Ie subsequent images may appear rotated. 

So my question - finally go to it - should I be making efforts to ensure the camera sensor/frame is mounted/rotated in the same orientation every time I take images to be stacked and how far out can they be before software like Deep Sky Stacker cant cope with it - presumably it would have difficulty stacking images which were rotated by say 90 degrees??  

john

[Mav359]

When i still used my DSLR with my SCT i came up with this to mark camera orientation

[Mav359]

Others better at this then me will confirm this but the camera orientation will only need to be the same if your shooting the same target over several nights where you intend to stack all off the data for one image. Even that can be got around but it makes processing easier.

[Mav359]

These are the templates but they may or may not fit ( i may need to email them)

[johncneal]

Thanks Alan - so what you seem to be saying is, its best to try and get the orientation the same each time, particularly where you want to stack images across multiple sessions. Your solution to aiding that looks simple and neat.

I assume this must apply to CCD solutions as well though - ie you still have a sensor to keep aligned. I guess the key factor becomes keeping within the stacking software's capabilities - or I suppose you could manually rotate the RAW files before DSS processing.

John

[Leveye]

Simple answer is yes. Set up exactly the same as the first session if you intend to stack these pictures.

[Mav359]

Thanks Alan - so what you seem to be saying is, its best to try and get the orientation the same each time, particularly where you want to stack images across multiple sessions. Your solution to aiding that looks simple and neat.

I assume this must apply to CCD solutions as well though - ie you still have a sensor to keep aligned. I guess the key factor becomes keeping within the stacking software's capabilities - or I suppose you could manually rotate the RAW files before DSS processing.

John

The way i look at it is this

if you pick a target, rotate the camera so that you are happy with the targets framing in the shot. Once you are happy with that make a note of the orientation (include it in the file name) and shoot that target at that orientation, this way whenever you go back to that target you can add to all your data together.