R.A. tracking, Drift Alignment & Imaging...am i understanding this right?

[c3po]

for the best possible images whilst piggy-backing for wide field images, i've been told that Drift Alignment and RA tracking is the only way for long exposure imaging, so i've looked at the Drift alignment process for my newtonian on its CG3 mount and i think i've got it understood, but lease correct me if i'm wrong - here's what i have so far:

1. roughly align on Polaris.
   
2. chose a star above the horizon on the southern meridian (i'm assuming this means a star directly south of polaris just above the horizon?)
   
3. using a crosshair EP, align the crosshairs N/S & E/W relative to the star movement (easy enough i guess...)
   
4. if the star moves North, move the scope azimuth East, and if it moves South, then azimuth adjust west.
   
5. now i understand i need to align the scope on a star in the Eastern horizon, and repeat the drift process. - how do i do this? do i move the scope unlocked on the R.A. axis?
   
6. once focused on the eastern star, if the star drifts North its too high, I adjust latitude DOWN, if it drifts South, move latitude UP...correct?
   
7. then i have to repeat steps 3-6 using the same stars until all (or near as dammit all) drift is eliminated.
   

Ok, so once i've drift aligned (assuming i've done it right - please do tell me if otherwise!) do i then unlock the RA & Dec axis and set up on where i want to image (locking the RA & Dec when completed), set the RA motor going and finally start the camera going - correct?

thanks in advance.

C3PO

[Pete Presland]

there is a great little video on here

http://www.andysshotglass.com/DriftAlignment.html

i used it to make a simple A4 guide to drift alignment for my 200pds. so i knew which way up was north and south and east and west, and which way to adjust them.

[Ags]

Hi, what focal length and what exposure length are you using? If you are using say 100mm focal length and a couple of minutes exposure (assuming a fast camera lens) then the setup is very forgiving and accurate PA should be enough.

[c3po]

there is a great little video on here

http://www.andysshot...tAlignment.html

i used it to make a simple A4 guide to drift alignment for my 200pds. so i knew which way up was north and south and east and west, and which way to adjust them.

Excellent video bunnygod, thanks for the link! i think i'll sort me out a laminated A4 drift alimnment 'Aide-memoire' for when i'm out with it for the first few occasions.... i suppose once you do it a good few times, it's like riding a bike.

Hi, what focal length and what exposure length are you using? If you are using say 100mm focal length and a couple of minutes exposure (assuming a fast camera lens) then the setup is very forgiving and accurate PA should be enough.

i'd probably be using focal lengths between 35 and 80mm for the really wide shots, and then maybe anything between 70mm and 210mm for the narrower images. IIRC, both my 35-80mm and 70-210mm lenses are f4.0-5.6 so not exactly great for AP, but i've been told it could be worse. Would these focal lengths and ratios be enough for, say 15 minute exposures on 35mm film? - i'm not using a DSLR as the bank manager says i can't afford one (pretty please...)

[Pete Presland]

took me a while last year,i use to go outside on nights that were a bit too cloudy for any serious observing.i must have looked a bit odd with a telescope out on a cloudy night, buts its surprising what you can see if its not too thick.

[Ags]

If you are looking at 15 minute exposures then you need perfect alignment regardless of focal length. Life is much easier with a digital camera :-)

[c3po]

If you are looking at 15 minute exposures then you need perfect alignment regardless of focal length. Life is much easier with a digital camera :-)

pretty much what I'd expected then for 15min and longer exposures Ags especially on film. There's just something about film exposures that i still think digital can't replicate without the use of filters, pre and post processing and whatnot, that's why I still love it so much...but with all things astro, it ain't half expensive!