Recently I have been comparing the bokeh of the following 135mm lenses:

Sony (Minolta) 2.8/135mm STF (T=4.5)

Sony (Minolta) 2.8/70-200mm SSM

Sony (Zeiss) 1.8/135mm

The results can be seen below. While the Zeiss is not bad at all, especially the shot at f1.8 seems somehow "flat". Both the Zeiss 135mm/1.8 and the Sony (Minolta) 2.8/70-200mm SSM are quite similar at f2.8. Then ... the STF at f2.8[T4.5]: what a remarkable difference! The image is really "3D" ...