I first want to make clear that I love my em5, it takes beautiful pictures, I am completely satisfied with it, I have no intention of letting lose of it. This is not a Pen-F is better thread. I am posting only because, on my picture taking outing yesterday, I took a few pics with my 14-150mm ii Oly lens. It is a fine lens for many purposes. It can produce very nice images. I have always been less than satisfied with it at its maximum of 150mm. I used that same lens on my Pen-F outing and my unscientific reaction to the pics, particularly at 150mm, was that the images just looked sharper and more defined than what it usually produces (see my recent post in another thread of small plane and kite). I am posting here a screen shot of two side by side examples of the same lens at 150mm with the same settings used on both my em5 Mk ii and my Pen-F - pics taken withins seconds of each other with a quick change act on the lens from body to body. In both, the left image is from my em5 and the right is from the Pen-F. There is a discernible difference at such close cropping at 150mm. This may be enough difference if you are taking distance shots of smallish birds. Feathers from one may look sharper than feathers in another. As I say, I am not making any claim of superiority of the Pen-F over the em5, but I will say all other images I tried this in (same lens on both bodies) did show the same slightly more defined and sharp difference. I would guess it is the sensor. I would not hesitate to use either bodies for any photo outing I was on.