Well, as is the case with things, I did get to the bottom of things, and it was in fact the shroud of my scope.
So now the idea is I have simply made a large black cardboard tube that surrounds the mirror to shield it from stray light when I do AP. This also means that the exposed mirror gets more cool air and remains closers to ambient then before. I have not however used it in very cold conditions this winter and likely will need a hair dryer close by!
An oversized shroud for my truss tube will do the trick.
John K.
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