Quote:
Originally Posted by DavidU
Wasyoung, I had a really close look at your images and It looks to me like it is slightly out of collimation and has a pinch in the optics.
Do you have (or can make) an artificial star? What collimation tools do you have?
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Hi David the 1st diffraction pattern,
06 Jul, was the original untouched factory adjustments. This was in reasonable seeing conditions.
The next diffraction pattern,
26 Jul, was after a minor adjustment, was in much more poor seeing conditions.
Some images, like the 06 Jul look as if the pattern is NQR..in this case pinched (on top) but I compared this with other images I did on the same night and in this case the "pinch" in the pattern is gone...It was just a seeing aberration when the pic was taken.
There is a slight concentric error in the 06 Jul image pattern, slightly up & to the right.
Here is another star image from the 26 Jul.
I reckon the pattern, while not perfect is "good enough" ...well at least not to cause this flare.
I have a pair of eyes
, star tests when the clouds go away
and a Cheshire
.
But from what I have found the star diffraction test is by far the best..when I can get one done!
edit:
I asked a about an artificial star for testing (like a Hubble Optics star) previously as I wanted to fiddle without relying on the weather nor a moving star..is it worth it? maybe yes in this case? Will an artificial star show chromatic aberrations or are they limited in their wavelength output? This I ponder some.
Here are some other star diffraction patterns 06 Jul (actually the 1st image is dated the 26 Jul). The Seeing varied quite a bit \which gave varied diffraction patterns. I noticed previously the pattern also shows some chromatic aberration on the diffraction images.
)
.
