KAF16803 based CCD cameras, images often show off-axis coma, astigmatism etc. plus even the slightest focal plane tilt will degrade a well corrected optical system's performance

While the standard 3.5" AP focuser works well with smaller cameras, a small focal plane tilt was evident when using a STX16803 plus FW-5 filter-wheel.

The system has sence been fitted with a FLI Atlas focuser. The Atlas moves the camera with absolutely no sag or hysterisis over its 105,000 steps and, albeit rather small, 1/2" travel range.

The above image is a SBIG STX16803 image of Omega Centarus at 100% resolution, with the centre and extreme upper and lower corners showing the edge correction.

copyright Peter J. Ward 2013