This is a rare 28mm lens made by CZJ, and has F2.4 with floating system.
8 grp / 8 elm, filter size = ∅49mm, MFD = 0.19m, 420g, $2,800 @2004

Probably made less than 50, hard to find this lens now or highly expensive if found
It was said ~260,000Yen around 1980's, very expensive for East German people.
(Even for the free world people too, my yearly income was CAD$45,000 @1985)
US$ was approx. 2 German Mark and ~230Yen, it was about 2,250 German Mark.