I got a photo of starry sky where I find different kind of aberrations on the left side and the right side of photo. It seems consistent in various photos so far, but this lens is quite new to me and I've had only so much time to get familiar with it.
The lens is a Samyang 14 mm f/2.8 ED AS IF UMC but do not take my sample photo as a proof of low quality. The sample is taken in high humidity weather with an entry level cheap system camera by an unexperienced star photographer - end of disclaimer.
This photo was taken with 20 sec exposure, f/4.0 and ISO 3200. Focus should be "quite good" for the photo is the sharpest one from a set of five that I took by manual focus bracketing. Image stabilizing is Off because I have the camera on a tripod and using a wireless remote shutter release. The Samyang 14mm lens is made for full frame camera, but mine has an APS-C size sensor, which means I'm not even getting the worst of the aberrations on my photos :)
Center of photo at 100% pixels:
Left and right side near edges:
On the left side some of the stars appear like vertically split in half.
On the right side the brightest stars have a bright blue shadow cast on the right side of the star and less bright stars have a lesser shadow.
What can cause the aberrations to be different on either side of the photo?
Full size fine quality jpeg image here (12 MB).