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| p.10 #6 · p.10 #6 · Just announced: Canon Rebel SL1, T5i & Powershot SX-280 |
Sven Jeppesen wrote:
Read a very detailed review about the 6D AF system at Digital Picture com, or at CPN. The center point is also much better for tracking with AI servo than those other cameras you say have the same AF point.
It's rather obvious that 3 AF lines is not the same as 2 AF lines. It's also obvious that 3 lines will pick up or lock the AF better than 2 will. More is better. And that's why the 1DX and 5D3 have 4 lines.
Allright. Let's take it apart. 61pt AF systems have "4 lines" in the sense that there is normal precision cross of the + shape, with additional diagonal high precision cross for the fast lenses, of the x shape. BTW, such a cross (maybe not that big, but of the same principle) is also present in: 40D, 50D, 60D and 7D. So if we take "line" as the pair of rangefinder baselines, then 20D, 30D, 5D, 5D2, 6D and also 400D and later also do have "3 lines".
Third "line" (i.e. high precision baselines) kicks in for fast lenses. Just look up older cameras' reviews.
Yes, 6D will see much better in the dark and it will lock where the other cameras would see no contrast. Therefore I write about good light. In dark, 6D wins, in good light, it can't use its only advantage.
Tracking is the function of the algorighms and CPU behind the sensor, of which Canon doesn't disclose any details (sans number of CPUs occasionally), therefore I keep to paper specs. We're not given any meaningful data by Canon on how good is the tracking on certain cameras.