Quote:
Originally Posted by strongmanmike
Those diffraction spikes do look ever so slightly double and thus out of focus to me 
I have always just focused by eye looking at an enlarged star on the screen in real time (usually 1 or 2 sec exposures) and without any sort of mask. I just press the in and out buttons until the focus star is as small as possible  in reasonable or better seeing it is quite a quick and easy process however in periods of bad seeing it does waste some extra minutes as it is harder to tell if I truly have the very best focus due to the star going in and out of focus due to the seeing...especially with the tiny CFZ at F3.8.
Mike |
Thanks Mike,
Do you have any shots of a bright star such as Alnitak that you could post - just for comparison?
I have re-collimated the telescope since those Alnitak images.
I have had a look at many other images before & since the Alnitak
image & I can't find any evidence of a twisted rope like
formation - rainbow colours - from any star's diffraction spikes.
Then again - none were so bright as Alnitak.
I will revisit this during my next imaging session.
It could be normal - but it could also be that it was slightly out of focus.
cheers
Allan