robert frost
This lens defeats the purpose of the reason people buy a micro 4/3,, !!,, I returned it. Mounted on a Olympus EM5 , it looks ridiculous large and is too heavy to enjoy taking photos while trying to hold body and lens(must) at same time,, I found the combination of the OLY pro 2.8 12-40 and the OLY 40-155 4-5.6 better for use on camera and not being heavy. Also I found the difference in F4 to 2.8 noticeable,, I would rater shoot at a higher shutter speed. in side by side comparisons of the F4 12-100 and the F2.8 12-40, the 2.8 was sharper in all its range. On the pros for this lens, it is a quality build and feel, has a hood cover and if you really are locked into using only the 4/3 body and ONLY want one lens,, then this may be a option, the cons are heavy, large and f4 limitation. for myself,, for $1200 I would not buy it.. . If I was only taking travel photos outside, and could pickup this for half price, I might be temped to trying it. But beware,, it is not a discrete street camera then and is certainly a target for theft. Overall I dont think OLY "hit this out of the park",,, its a miss.