This was 30-40 degrees up - might be the reason.
but also, in the corners the stars turn into a 'c' shape, i dont think it is the spacing, but here is my setup: dslr44mm > tring10mm > 6mm t extension > flattener, so within the 2mm sweet spot.
Lewis, how do ensure that the flattener is orthogonal?
PI maps attached, looks like i do have some problems:
