Coma, focus, tracking or collimation... Need help

[Skyhawk727]

Have attached a single sub I took last month of M13.  I have a fairly new (less than 1 year) 10" LX200GPS ACF and DSI III Pro. Scope is polar mounted and was used at f10 without any focal reduction or field flattener.  Exposure time was 5 seconds.

 If you look at the image closely, the star images are severely elongated and I am not sure why.  The scope has what Meade claims are Coma-Free optics, but it looks like coma to me.  The short exposure time and elongated star images make me think guiding is not the problem. 

Collimation of the scope looks OK to me but may be the culprit.

Any ideas will be helpful as this is the first photo with the current combination of scope and camera.

Thanks in advance for any input.

Dave

Northern Illinois

[Mark Sibole]

Make sure your imager is sitting square in the holder
Also e mail me the full size image so i can look at it closer

astronomy  at  qteaser  dot com