Originally posted by rfortson I suspect you've hit on the complaint. Again, I don't do staged tests so I'm not measuring absolute AF speed. My real-world experience shows the AF speed is quick and snappy for whatever subject I point it at.
My experience on the 50-135 is that it's quite quick in good light on my K20D. In low light though it was quite sluggish, even with the AF-assist lamp from the 540 flash. I had a hard time catching those fast and spontaneous moments at the last wedding I shot.
Very nice lens, but is quite behind in AF speed to catch up to the Nikkor 70-200 lens I used to use. That lens and the Canon variant would literally just "snap" onto focus pretty much the moment you half-press. But then again, that's a lens that costs 2-3x more.
I like the 50-135. Very good optics, great build, sealed, great handling, fast enough in in most situations, all at a very good price.