help with m27 image

Hi all.

I have racked my brains over the last little while to figure out what has happened in this image. The stars seem to be vinietting but in differet directions.

The stars are pointing down on the left hand side and across on the right hand side (not as pronounced as in a previous image I had but nevertheless the same).

I wonder if this is as a result of the focal reducer I am using. ie the Atic 0.5 reducer. (The glass in the reducer actually rattles it is that losse).

Would I be better off getting a meade or celestron version? Im accross the atlantic next week so I will get a chance to get it cheaper then.

Is there anything else that could be causing this effect?



Thanks for any comments

DB

It ain't vignetting (gradual light loss towards the edge of the field.) I think you may have answered your own problem - if the lens in the corrector is physically ratteling then it may be shifting during the exposure (for whatever reason) causing the 'double-lobes' on the stars. You should be able to tighten the retaining ring on the lens fairly easily - just so that it holds the lens secure... not tight. If that doesn't cure the problem then all I can suggest is that you try to avoid tripping over your scope while exposing - another common cause of duff star images!

Phil.