Quote:
Originally Posted by Ryderscope
........ Also, the star shapes are elongated as opposed to the ‘triangular’ shaped that is evident in the blue channel. From my experience, the triangular shaped stars only come from collimation errors or pinched optics. Again, this last point brings up the conundrum of why is one channel affected more than other?
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The rear mounted Pretzval element can, in my experience, be susceptible to colour shift because of the nature of the optical design. The Spots show some shift. If this was an APO with good glass, and a traditional Reducer or Flattener, you may not notice anything.
I note that the FRA600 is much worse in terms of Spot offsets, and this was mentioned on Cloudy Nights as well. So is it a 'feature' of this design?