CAF and me
As many have said before, C-AF has never been a strong Olympus selling point, or for 4/3 as a whole for that matter. C-AF works very well on 4/3 for a number of uses, and not so great on others.
C-AF works well in situations where tracking is easily obtained, and where the DOF is great, masking any fous tracking mistakes. For example, take your example of tracking a plane in the sky (and lets assume a blue sky). Exposure on a sunny day is going to be around f/5.6, ISO100, and 1/2000s. Shooting under those conditions, where the plane is perhaps 1/4 mile away, at f/5.6 against a blue sky,and you will get great results. Why? Even if your camera mis focuses, it will still be in focus, because the DOF is so great.
Change the scenario to what i very commonly shot, using the E-3 and 35-100, where its a cloudy day at 2pm, exposure around f/2, ISO100, and 1/125s. The E-3 and 35-100, under these (otherwise normal) conditions, has a very hard time tracking a slowly walking person. So much so that C-AF is almost useless. In these conditions, you'll get better results feathering the shutter in S-AF mode. Now, throw on the 12-60mm or 50-200mm SWD, and the story is completely different. Why? First the focusing is faster on SWD, but second becuse you're now shooting at f/3.5, giving a much wider DOF plane.
These are two sides that illustrate why there is so much debate over C-AF. For some, it works great (maybe they are shooting planes against a blue sky in good light?), and for others C-AF is a nightmare (like for me, shooting an engagement with the couple slowly walking toward me).
As with most of photography, it depends on your uses and application. Will switching brands help with C-AF? If you're shooting planes, probably not. If you're shooting in more demanding scenarios, well then, maybe.
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