[Klaus]

I am not surprised. 

 

Such ultra-high speed lenses make good press releases and raise brand awareness.

However, a 1/3 stop advantage compared to the mainstream just doesn't cut it to start with.

[Brightcolours]

It can also be 1/2 a stop. Things are murky around the f1.2 number...

Half a stop above f1 = f1.1992 -> f1.2

Two thirds of a stop above f1 = f1.26 -> f1.2