Quote:
Originally Posted by Joshua Bunn
Greg, have you tried the accurate polar alignment procedure? You get visual clarification of your mounts movements this way, not relying on the tic marks of the mounts alt/az adjusters. I would try 1 model that has been super modeled, and about 50-60 samples all over the sky. Doing it this way should get you there in 1 go, it's not an iterative procedure. This is what I did some time ago and haven't looked back.
Josh
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Quote:
Originally Posted by PRejto
Greg,
I agree with Josh. The best way now is the new method that uses fiducial stars. It takes all the error out of moving alt and azi. And, if I understand it correctly, unlike the old way, once you move the mount based on those stars you are done as the model updates itself to the new position.
The other night, after you did the big super model I presume you recalibrated back into it after you made the adjustments. If you didn't then the model is just messed up but easily fixed by recalibration. What you didn't say is whether you got eggy stars unguided or guided. If you didn't recalibrate then eggy stars are guaranteed unguided. But, if guiding maybe Protrack was/is fighting against guiding corrections as Protract would be constantly telling the mount to move incorrectly (since the model isn't pointing where it thinks it is). One would think that guiding would win but it would need to work a lot harder.
The arguments between T-point and drift alignment (PEMpro) are endless and I think in the end pointless (ha ha). Once you are close enough by either method a good pointing model + Protrack will give really good results. Even Patrick Wallace has agreed that a drift alignment can be good enough provided there is a good model to back it up. As best I understand drift alignment is just a compromise giving no error for just that region of the sky whereas T-Point tries to give recommendations for most of the sky one would image in + giving different recommendations to minimise field rotation, etc. taking flexure in the imaging system into the equation as well. Since all PA is a matter of compromise being close enough is good enough.
Peter
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Thanks Peter and Josh.
I did use accurate polar alignment on Friday night and yes it did give me round stars. I was a bit sceptical of it as the PA report showed only minor adjustments and the accurate one had me moving it more. So I was worried I was moving away from the actual point.
I think tonight I'll do a 200 point model and use the accurate polar alignment recommendations. Pempro has something similar where you do a drift alignment and then next step is to click on a star in an image and move the mount so the star is at the end of an arrow. It seems strange to adjust it even more once you stopped drift. I guess its another level of accuracy.
Greg.