[Klaus]

Christopher Frost has done a review of the 28/F4.5 ..... it came out quite well on FF, very sharp in the overall frame even sharpness in the corners was decent, on APSc the corners were good-very good ..... flare was "artistic" and sun stars pretty good  .... AF was also decent.
 ..... at $99 it's a steal, less if you sign up on their site ...... and it's well made with a metal mount ....... 

   I take it back it's quite a sweetie and a true pancake rather than a crumpet .......

 https://www.youtube.com/watch?v=KbzimUlO9P4

CF has also reported soft corners on FF ...