Drift alignment using a DSLR camera

[malc-c]

Guys,

Murphys law, both my batteries have just died whilst spending the night to set the mount up usinng the attached guide, so time to post a question.

I started by picking an area where the galactic equator crossed due south, found that there was some deviation for azimith so spent an hour dialing it out until the star tracks were back on themselves and the star was dead centre of the line it traced out.

I then turned the scope west and the lowest star for me that was almost directly due west was Archtarus (sp?), so it was centred and I repeated the procedure... dialed out the drift using the alt bolts and got a nice track. Then did a 3min exposure and I still got oval stars. Went back and repeated the procedure with the scope still pointing west but this time done a 125sec exposure so to get more accuracy, dialed out the small minute difference and then took a further 3min exposure and this time I have drift in west to east plane not north / south ???

Any ideas ?

Zeroing it in. Using a DSLR or CCD to Align Your Scope.pdf

[Merlin66]

If the alignment is good then the resulting oval images may be due to the drive train accuracy.

[malc-c]

I didn't get round to trying out control via the handset rather than EQMOD due batteries not being charged and the fact that there was more cloud than gaps by around 1:50am so I retired for the evening.

Last time I did this, even with the poor alignment, I had better tracking using the handset than through the PC. Could it be that the handset already has this correction built into the firmware, and that I need to "train" EQMOD about my mount ?

If I get chance today (24th wedding anniversary today so time on the PC is limited ) I'll post up some of the images.

[malc-c]

I've just processed some before and after pictures for both alignments with the scope pointing south, and west, and then the resulting trailing of an image with 112sec exposure.

The "close" image is a section of the main picture at 1:1 pixels.

I would of thought the EQ5 would be able to track for longer than 112 seconds without drift.. ??