Quote:
Originally Posted by jayscheuerle
Focuser tilt is irrelevant to star shapes. The only important aspect of the focuser is that the movement in and out follows a straight line. There's nothing special about a 90° angle. Lowrider dobs are purposely tilted quite a bit. - j
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Hi Jay,
On my fast (F5) Newt the elongation on the large QHY-8 chip is quite
pronounced even when only slightly tilted off axis.
This could be because of the chip itself being tilted off axis slightly within
the QHY-8 housing, tilted off axis due to the focuser, incorrect spacing
of the MPCC or a combination af all three.
The MPCC problelm shows as coma and is almost nil on my setup now.
The CCD off axis tilt is also minimal as I have proved it is not that by
imaging with a slight rotation around 360 degrees on successive nights.
So the only culprit must be the focuser and , as the OP of this thread
shows, it was quite noticeable and I'm amazed I missed it for so long.
Steve