Thanks Guys for all the advise! When I did these tests I used a control box which I built to control the speed of the motor to give exactly 1 RPM. The power supply is a 12V 7ah battery.
This is the Tracker I based mine on:
http://www.tucsonastronomy.org/barndoor.html
After playing with the tracker this morning I think my problem might be that the nut which rotate on the rod is not totaly symetrical, so as it rotates it rises and fall a little which gives me my wiggly stars. So I will endeavour to fix this....
However the stars do seem to drift down (or up) in the image. Is this alignment or does my tracker track to fast?
I'll have another play with it tonight and see what I get. I'll try to teach myself a bit of drift aligning.
