[mst]

Good question... want to guess?

I mean, it's just half the price, even a lot less if you can live without rangefinder coupling (not a good idea on the M9, though, but may work on the new M with live-view and certainly the A7/A7r), coming from a young chinese company building toy lenses (among other things) and not the highly regarded German brand with almost 100 years of history and experience in building quality lenses... a new kid on the block trying to attack the premium product of a well established quality brand, so, how good could it realistically be?

-- Markus