So reflecting over what makes this a 'different' lens than the rest in this class; The large front element of the lens helps greatly to make foreground subjects 'wash out' very well.
This is seen also with other lenses with large front elements like 200mm f/2, 300, 400mm f/2.8 and the big f/4 lenses.
You are able to shoot straight through object and at the same time 'look around' these object and see the main subject. Gives a fantastic effect INHO that shorter focal length lenses, although fast can't do to the same extent due to the smaller front element.
First the 105mm AFS 1.4 a blue bicycle bell is in between the lens and the flowers,,,
_EGL6547 by
Erik Gunst Lund, on Flickr
And here a shot with 500mm f/4 at f/4 for the similar effect.
_EGL2646 by
Erik Gunst Lund, on Flickr