DXO's Pentax K-5II Review

I was going to buy one (K-5), but the sealed lenses offer seem not on par with the body's IQ? Lots of great lenses for Pentax, no doubt, but when you don't live in laboratory conditions, weather( and dust) seal is a plus.

As a 7d user (second choice after the K-5), a second lighter body for landscape or travel/street would be nice, and if Pentax had a nice sealed 20mm pancake it would be nearly perfect. In fact I can't understand that nobody offers this kind of lens, must be for some technical reason. I have the 40mm 2.8, but after some weeks it already had a big dust particle (particle is too light here) INSIDE the rear lens, it probably already was there when I bought it, I wonder if I could use the warranty to sent it back for cleaning?