Bit embarrassed to say that I am still learning how to use the Hyperstar III.  Rather humbling when I thought I knew all there was to know about getting the best out of the Hyperstar.  I had done a few camera swaps on the HSIII and I was having difficulty getting good stars across the whole of the M25C, something I had not had a problem with before.  Now here is where I was going wrong.  I thought that I could have the M25C adjusters set so that the face plate was perpendicular to the camera body (this means the chip would almost certainly not be flat to the optical axis) and that I could sort out all the chip flatness/collimation with the Hyperstar III adjusters alone.  THIS IS WRONG!!  I slowly caught on that I was not going to get good stars across the chip using the HSIII adjusters alone after spending around 3 hours playing about chasing my own tail – it was clear that the HSIII adjustments were not enough – YOU NEED THE CAMERA TO BE FLAT TO THE OPTICAL AXIS BEFORE IT GOES ONTO THE HYPERSTAR III.  Oh well – live and learn.  So I used Terry Platt’s method as given on his website to flatten the M25C APS-size chip to the optical axis, and I put the camera back on the Hyperstar III last night.

I ran the FocusMax autofocuser on Sulafat (Lyra) and the first 20-second sub looked pretty good without touching the Hyperstar collimation adjusters.  A CCDInspector look at the sub gave me the magic x = 0, y = 0 for the chip flatness (can’t do much better than that), and it gave me 2.7″ for the collimation.  I have never seen a set of CCDInspector numbers this good before for the Hyperstar III/M25C combo.

Hopefully I’ll be turning out some interesting Hyperstar images once again in the not too far distant 🙂

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