[raymo]

The radial coma pattern far out from the centre of the image is quite obvious, but if you mag your screen to 175% or so, you will see that all the stars at, near, or even fairly near, the centre of the image, are elongated top to bottom of the screen, with very little sign of leaning left or right which coma would do. I must have another look to make sure I'm not
talking bulldust, my old eyes struggle a bit these days. Had another look, and even the stars at the centre of the image are
elongated; from memory, my f/5 gives round stars about a 1/4 to 1/3 of the way out from the centre.
raymo