I am new to Micro Four Thirds photography and I have read quite a bit about the different lenses that are offered. I am shooting with a E-M5 and I have been reading about the old and new version of Olympus lenses. I have seen some used lenses and after reading about them, I read where some of the older versions were not as sharp as the newer versions. My question is, how do you determine the new style lenses from the older style of Olympus Micro Four third lenses? I read some where that there was a version II lens as the newer lenses, but I was wondering how to determine those lenses from the older lenses. My second question, is whether there are any disadvantages of using non Olympus Micro Four Third lenses on the E-M5? I have heard some very nice things about the Panasonic lenses but I am not familiar with them.