Build quality: good
Filter thread: 58mm
Infrared Mark: yes
Just when I was impressed with my Tokina 24mm, I found this superbright 28mm on ebay. While its brightness advantage over my Beroflex 28mm is nice, it seems a little bit less sharp and with a hint more distortion.
However, it quickly became my lens of choice for those low light photos where I need a rather wide lens. My 24mm Tokina is "only" f/2.8 and the 35mm Porst is faster at f/1.8, but it's like 52mm vs. 42mm. So, the 28mm 2.0 gets the place in the bag.
For some boring brick wall test images, look here.
More shots with this lens in my Gallery: Tokina_28mm_2.0.html