The lenses focused surprisingly fast. This is likely partly because of the new internal focusing design they share, having been designed to focus rapidly and silently during video capture. Indeed, there was little to no vibration or sound made when focusing. The E-PL1 wasn't made to keep up with high speed tennis action, even in continuous AF mode, but in single focus situations it was able to lock on and get a lot of shots even when the subject had just run into position to hit the ball. In fact, it was often so fast that I could pre-focus when the player ran into position and then wait for the right moment to trip the shutter so that the ball was in frame when the player was hitting it. This wasn't the case with the 300mm f/2.8 Four Thirds lens mounted on the PL1 with the help of an MMF-2 Four Thirds to Micro Four Thirds adapter. While its autofocus couldn't keep up with the action, it provided a nice clear view, complete with a pleasantly defocused background, in situations where there was ample time for prefocusing, meaning not very often.