Quote:
Originally Posted by JA
Hi L,
I think that's a wonderful result, especially as you've REALLY tested the limit of its 40-44mm image circle (depending on model - you don't say which), by using a full-frame sensor. Even zoomed in tight there is no observable chromatic aberration and very even illumination of the field (except perhaps in the extreme corners, but that is to be expected with a full-frame sensor used on an optic with a full-frame image circle, even then it is very minor and easily corrected in post).
The only thing I do notice, only when tightly zoomed in near the corners, is a sort of cross or Maltese Cross shaped diffraction pattern which is more evident on brighter stars, which gives them a slightly squarish appearance. I wonder whether this is the result of using an On-axis-guider and caused by diffraction from the edges of its prism or possibly some other sharp edge in any adpators, etc in the optical path. It may even be stray light entering the edge of the optic and bouncing around and hitting things it shouldn't like the edges of internal baffles, etc. Was a lens hood used?
In any event it's an excellent result, with detail that will build as normal with more exposure. One can already tell that from the detail in the smoky reddish gas around the core. It would be great to see a head to head comparison of the same object with your other Tak optics, under the same conditions.
Best
JA
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JA, thanks for this. I wonder if I’m undesampled? And that’s the pixels coming through? Hmmm... I also updated the above with scope details: FOA-60mm. Essentially, a baby TOA. Agreed, more data needed, and a comparison would be interesting...