Out of focus some times, on some colours
Getting back in to astro photography after a bit of a break, I'm using my ST7 + CFW8 with a new adaptor that lets the optics of the F/6.3 reducer fit inside the 2" draw tube. So my optical train has changed since last I used it.
Something bizzar is hapenning that I can't explain...
I focus using FocusMax with the clear filter (no filter), then take a colour series. Clear is always in focus, the others - Red, Green and Blue, vary from shot to shot (even for the one colour) being in focus or slightly out of focus to different degrees.
I really can't pick why the focus is changing slightly. The robofocus sure isn't moving, neither is the NGFC slipping from what I can tell (and that adds up considering the clear shots are in focus). But why the colours would go in and out of focus.... I'm confused...
Ideas?
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