Quote:
Originally Posted by BruceG
Hi Graeme, thanks for the encouragement. I don't know if I can go longer with the subs - my raw exposures at t 3 minutes are quite red all over, which I assume is sky glow? (although I don't know if it is or isn't) - I haven't tried to go beyond 3 minutes, but it is worth a try - maybe 5 or 6 minutes.
I like the idea of leaving everything set up for consecutive nights, only that the weather never seems to co-operate. I do have a method of achieving reasonable polar alignment at each setup. I have 3 right angle brackets hammered into the lawn - these already come with 2 holes through each face which allows the end of the tripod legs to stay securely in the holes. I spent a long night initially leveling everything and a couple of hours of drift alignment. In the end I was aligned quite well. If I don't collapse the tripod, I can plonk it into the appropriate holes, set the telescope and other bits and pieces on it and I'm ready to image - I call it my poor mans pier. These brackets were not my idea, but a good friend of mine, Mel, who is responsible for me taking the plunge into astronomy after a virtual lifetime of interest in the subject.
I guess the only other thing I need do to ensure correct registration of the 2 sets of images is to leave the DSLR on the scope and the scope on the rings - although I'm thinking "align and rotate" would correct that (am I correct here?).
Thanks once again for the advice - I need as much as I can get.
Cheers,
Bruce.
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Hi Bruce,
Nice shot.
The red is caused by thermal noise in the camera.
It is always much worse in summer.
Couple of hours of drift alignment?
You can get a perfect drift alignment in under 15 minutes
if you use your camera & it's so easy:
To adjust the right ascension:
Point North at about 50 degrees altitude.
Take a 70 second exposure while tracking for 5 seconds, slewing E for 30 seconds then slewing W for 35 seconds at a x1 rate. Your image will show a star and a V shaped trail. The size of the opening of the V at the is the amount of drift in 60 seconds and its location relative to the star shows you which way the mount needs to be adjusted. Adjust the RA screws left or right mount until the V collapses to a line that passes through the star and you'll be polar aligned.
Elevation alignment is similar but point the mount to the Eastern or Western Horizon & adjust the elevation screw.
cheers
Allan