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Very impressive first images Bert. These are better than I expected. No real evidence of coma even though your chip is larger than the specified corrected circle of the scope.
Bottom left shows slight tilt and top right shows something similar but almost slightly coma. I'd say your getting a small amount of tilt (it may be only .15mm tilt here to get it in perspective).
I've seen similar tilt issues on other scopes and its only a small amount of tilt. It doesn't take much with that large chip.
Further polar alignment and autoguiding will take care of the guide errors. A few runs through T-point will get it singing.
I recently redid my T-point model and refined polar alignment on my PME and CDK17. Now I get objects in the middle of the chip on go-tos and round stars at 20 minute sub exposures at 3 metres focal length.
These SB mounts are awesome.
T-Point is an amazing tool and well worth the learning curve. Sky X T-point is even better as it has the super model function.
You're on to a winner here Bert.
Keeping temperature stable is a smart move. How are you going to do that?
I think ideally the scope mirrors are a tad cooler than ambient. Hotter is bad for sharpness. At F3 it may not be as noticeable but at long focal length it is definitely noticeable. I turn the fans on my CDK17 on a few hours before I use it. I need to get the mirror .5C or less to ambient to get sharp focus. If the difference is .1C it starts looking a little bit soft.
I'd like to hear how your Lodestar goes. I am using one but I have an SBIG STi on its way to me. Main problem for me with Lodestar is CCDSoft does not seem to do library dark subtract when autoguiding. I either use autodark (and that subtracts half the star unless its moved enough) or none if the guide star is bright enough.
I found my Lodestars have had artifacts . A horizontal white line plagued it and affected guiding (auto select guide star would pick an artifact over a real star). This artifact disappeared when using 64bit driver on my Win 7 laptop. But 2nd Lodestar has a white line down left side and it is sometimes selected over the star. You can tell when it has as guide errors go up to 15 pixels! I simply use autodark when this happens. I get slightly worse guiding performance using autodark (there is no shutter so it can't do an accurate autodark and subtracts part of the star as well).
Lodestar is designed to be used with PHD so perhaps all this goes away with PHD - I've never tried it. ST402ME is the best autoguiding camera but a bit heavy, plus 2 cables - power and USB. Its super sensitive and cooled so very little noise and no autodarks required. Plugs on mine were a bit unreliable though. Back to service it goes.
Greg.
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