baseball and mountains
I have photographed minor league baseball iusing Nex 7 and SEL 55-210 lens, almost always at the long end (i.e. 210). There are two requirements I have found in order to photograph an outdoor action sport such as baseball: 1) focus fast and 2) minimize camera shake. (Indoor sports also require wide aperture/high ISO). The SEL 55-210 has BOTH auto-focus AND image stabilization, making it a great choice for such outdoor events. I can easily hand-hold to auto-focus either the pitcher or the batter because their movement is within a confined space when either throwing or swinging.
However, it is MUCH harder for me to capture handheld a fielder making a diving catch, or a baserunner sliding into a base, because these actions take place too quickly and are moving targets. Best way for me to capture such action, particularly baserunning, is to pre-position and pre-focus the camera mounted on a tripod pointing to a particular base, and then fire off a burst of shutter clicks in auto-shoot mode via the remote commander when there is action taking place at that particular base.
I do have the LEA-2 adapter but I don't need it for baseball games because of having the 55-210. Besides, mounting the LEA-2 and an Alpha telephoto lens adds heaviness and subtracts image stabilization, thus preventing such a jury-rigged combo from shooting hand-held at the long end.