Crescent HaRGB

Hi all. Here is an attempt to do a color version of the Crescent Nebula. I am pleased with parts of the image, but I am getting stars that are elongated in the corners. I thought that the flattener would correct this, but this was shot with the flattener and it still has the problem. The CN-212 is a very fast scope at F/3.9... perhaps I need a paracor? Any suggestions?
Cheers,
Tyler

Info
Tak CN-212 on Losmandy G-11 with SBIG ST2000XM
Ha:R:G:B 120:10:10:10
Maxim and Photoshop

Attached Image:

Hi Tyler,

Is the elongation happening in all corners, or just one or two?

From what I understand, if the star elongation is across the entire frame (visible in all four corners), you will need to position the camera/flattener at just the right distance. All flatteners/correctors need to be just the right "metal back distance" from the imager for the correction to work at its best.

If the elongation is happening in just one corner or side, you are probably seeing flexure in your system, i.e., a miniscule "droop" from the weight of the camera. Or, the camera might not be perfectly square to the tube.

Nice picture overall, though!
Eric

Looks like the image was taken in the "newtonian" mode, in which case I would say your image is suffering from coma. A coma corrector for newts is what you would need. Try imaging in the cassegrain mode and see if you still have the same problem.

Check you have the flattener at the correct metal back distance.

Greg.

Great job Tyler. Very nice colors and detail. Thanks for posting it