Originally posted by steve917 I am seriously considering Buying 1 of the 2 and would love to hear feedback from any owners of these new lenses.
I bought a DA* 50-135mm f2.8 when it was "on sale" at B&H. I have had it for about 10 days, and got the opportunity to really use it a couple of days ago. It is a fine lens and is a convenient replacement for three prime lenses (50, 77 and 135mm). It is well-built, but the exterior is 100% plastic, so not as nice as a Limited. It is large and slightly heavy but handles nicely and is much smaller than a 70-200mm f2.8 for a 35mm film camera.
It is a pleasure to use. AF is faster than any screw-drive AF lens that I have used and it is almost silent. All you hear is a
very faint click when the motor starts or stops. In low light, there seems to be less hunting: it either focuses or the AF confirm light flashes. In actual use, I get more pictures in focus when using AF as compared to a lens like the Pentax FA 77mm f1.8 Limited. Both zooming and focusing action is smooth and well-damped. I love the quick-shift focusing feature and the wide focusing ring. The focusing ring doesn't turn when the AF is used, making the lens very convenient to handle.
Image quality is outstanding for a zoom lens. Even wide open, it seems sharp and contrasty at both the center and edges. Image quality improves when stopped down up to about f/8. It is at it's worse at 135mm and wide apertures, where the edges are slightly soft and there is a small amount of CA visible at the extreme edges. Stopping down one or two stops improves the quality. In comparison, the Pentax FA 135mm f2.8 [IF] is sharper in the extreme corners from f/2.8 to about f/5.6, but the difference is very small. The only area where performance is a bit disappointing is the minimum focusing distance of about 1 meter.
Overall, I'm very happy with the lens. It has the convenience and flexibility of a zoom with outstanding image quality.