I took these two pictures directly one after the other, with only shutter time and aperture differing. Both pictures were taken using EFCS, disabled IBIS, and with a 2s delay timer (on a tripod obviously).
A third exposure, DSC_3749, taken directly before 3750 at the exact same values (1.3s f2.0) shows the exact same effects on the lights as 3750. That’s why I would exclude things like wind-shake or other environmentally-caused vibrations as the source. Could this be shutter shock, even though I used EFCS? Or could it be an effect of shooting at wide-open aperture (the lens used is the Nikkor Z 40 mm f2.0)? Or is it something else entirely?
I’d be thankful for any clues as to what might cause this and how to avoid it in the future!
The artifacts around the point-source lights look like they bend in opposite directions from the two sides of the photo. That looks like an optical aberration to me.
It looks like astigmatism, because the point lights are smeared along concentric circles. The aberration would be worst at wide open aperture and should be reduced or disappear entirely when stopping down.
Yes, it’s almost certainly astigmatism of the lens I used (Nikkor Z 40 mm f/2). I just found this review of the lens which briefly discusses its astigmatism at wide apertures.
