Erno -
That is a brilliant shot --- great composition with the tree branch overhead. I'm not sure if the wide-angle lens created a bit of curvature in the surface of the water... it seems to curve down a bit on the right. I'm being super picky here, but only because this is such a top-notch photo that you tend to start looking for tiny details like that.
Meanwhile, happy comet shooting! I hope it works out. I have an app for my iPad called "GoSkyWatch" and they just added the comet to it (along with comet ISON which is coming this fall). So if you use the app, it might help you locate it.