Originally posted by sajah I have both and at a time did an unscientific test, just trying to shoot same things with DA15 on K-x and SEL16 on NEX-5. I didn't (and still don't) have K adapter that can change DA lens aperture so I couldn't do both lens on NEX-5 only, but K-x and NEX-5 presumably use the same sensor. Outdoor, stop down to F8, I couldn't really tell the difference. Except that, DA15 creates beautiful starburst while SEL16 starburst is awful. I will try to upload the photos tonight if I can find them.
During 1 year experience I found sometimes SEL16 is soft in indoor wide open, but on other ocassions I found it very sharp. The softness could be related to the DOF as it's 2.8 compare to F4 of DA15 and also the lack of Image Stabilization. With K-x and DA15 I never found similar softness, unless I click shutter too soon and the IS wasn't ready (very rarely).
I guess the built in image stabilization should equalize out the 1 stop difference. The reviews say neither lens can be used wide open for landscapes due to soft corners, but that both have sharp centers wide open, and the Sony suffers a little bit more, due to soft corners, even stopped down. I was mostly curious, because Pentaxians love their DA15, but the Sony lens is not as highly regarded. Its hard for me to justify the $500+ dollar price tag, but the Pentax flare resistance and star bursts seem really cool. The size of the DA15 would be greatly preferable to the 16-45mm. For wide angle, I prefer a smaller lens, (even though I greatly appreciate the Tamron 28-75mm, and the DA55-300mm). And then sometimes I think I should just get a Nikon P300 (24-100mm) to throw in the bag, except that it has no viewfinder.