Terrible Flats

[steppenwolf]

Hi folks, I wonder if any of you can throw any light (oops, pun!) on the following.

I enclose a FLAT taken with my SXVF-H9 through my Sky-Watcher 250PX with analysis by CCD Inspector. Any thoughts on why the light is so skewed? I have checked collimation with a Cheshire and a Laser collimator and all seems well with that aspect of the optical chain.

I have an ATIK Filter wheel with 1.25" filters (Ha for this flat image) and a Baader MPCC (correctly spaced) in line. If I rotate the camera through 90 degrees, it makes NO difference to the flat image. Flats taken through just the CCD with the ATIK Filter wheel with 1.25" Ha filter and the MPCC but no telescope do not show this skewing.

[davew]

Hi Steve,

If I've understood your methods then the only thing I can think of is the internal wheel has moved. That would then place the filter out of line.

So, the wheel has some slop or the magnets have some slop ! All I can suggest is you remove either the camera or the MPCC, rotate the whole lot and see if the wheel moves. Or... open the wheel housing and see if it's all tight inside.

Damn odd.

Dave.