Samyang 16mm f/2 star field test. Can you find any faults?

[Felias]

I tested my new lens on Saturday night. I thought that pointing at a random star field towards the zenith (I caught Cygnus nonetheless) would be good to detect any serious aberrations. This is a fast shot, just 3 seconds, ISO 6400 F/2, so never mind the noise, I just wanted to avoid any star trails. It seems normal to me, just what you would expect in the corners (perhaps the distorsion is slightly more noticeable in the top right corner?), but I thought I'd post it in case someone with a more trained eye could find any faults in the optics. I have not applied any lens correction.

Thank you!

Edited August 30, 2021 by Felias

[wxsatuser]

It has sagittal astigmatism/coma in the corners, the flying birds, with some chromatic aberration and vignetting.

Not unusual for a lens of this type, not massively obvious unless we pixel peep, about as good as it gets at f/2 imo.

[Mr Spock]

Looks really good for f2. I'd be really happy with that result. Might be better at f2.8 though.

[Alien 13]

Looks good to me and certainly usable at F/2 especially if you are shooting on a static tripod and want foreground included, worth trying the lens correction data too.

Alan

[Felias]

Thank you so much for all your replies. Yes, coma and chromatic aberration seem to fall within acceptable limits in the corners. Things improve at f/2.8, with stars looking much sharper (some diffraction spikes start to show though), so I'll probably get good results at this stop on my star adventurer. I knew this lens caused quite some vignetting before I bought it, so it's not unexpected.

I have tried lens correction, it's just a barrel distortion that Lightroom fixes nicely. That doesn't affect star shapes in the corners, of course.

I guess I'll be keeping this lens! 👍