Honestly, I became a bit confused with the lens after some time of using it and shortly I switched for K-1 and 15-30. The 11-18 is superbly sharp with no CA even in harsh conditions. Sunstar is not as from DA15Ltd but not bad at all.
Just a test image when I got my copy few years back... But I was pleased with the sunstar. I expected to be worse due to the modern diaphragm.
And few while shooting night city.
BUT. The flares and coma is really bad. When the sun is in the FOV or near it its impossible to do one-shot pictures. Loss of contrast, rainbows, bright spots… You need to stack images in PP with corresponding shots with finger covering the sun. When shooting astrophotography wide open, the corners are unusable. Coma is very prominent at f2.8 :-(