[iceman (Mike)]

Hi guys

Last night was the first light for the WO 0.8x reducer/flattener. First thing I noticed, was some sort of field curvature/rotation on the corners.

Here's what I was hoping to frame last night, NGC253 with the glob in the bottom right, but when I saw the curving stars, I decided to stick to NGC253 alone in the middle of the frame where the stars were sharper.

This is a 2 minute exposure taken in jpeg, just adjusted the levels so you could see it. It seems to only be in the top left and bottom right corners.

I don't remember getting that curvature without the WO reducer. What am I doing wrong? Or is just my tracking? Looking again now, maybe this image doesn't show it well enough.. the stars in the middle are still elongated a bit (from bad tracking), but the ones in the corner appear much worse.

What's the thumb-screw on the WO unit do? Why does it need to rotate around, and it also appears to be able to slide in/out just a little bit when the thumb screw is loose.

Thanks