What is this and why is it happening

[arthurking83]

Is that the 50/1.2, Snorter? It seems to get a lot of criticism for this (and a few other) issues, though it has some very dedicated fans as well.

99.9% most likely is, and Nikons fast glass does it too.
85/1.4, my 50/1.2 ... etc.

Someone mentioned the coatings, which are supposed to help(Nikon uses ED nomenclature) but they even those lenses still produce PF.

I suppose one reason to have the fastest possible glass is that you can stop it down by one stop or two to minimise the effect, eg a f/1.2 lens stopped down to f/2 probably won't be as affected as a f/1.8 lens will be at the same aperture.(eg. the Nikon 50/1.2!)