7D AFpoints - Indicated vs Actual

Started Feb 7, 2013 | Discussions thread
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Dale Buhanan
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7D AFpoints - Indicated vs Actual
Feb 7, 2013

I had posted this link once before, but it was buried deep inside another thread, and I don't think many people got to see it. I thought it was such valuable information, that others would want to know, so I am posting it in a new thread.

This guy (Andre) has gone to the trouble to measure the extent of the cross type sensor boundaries on the 7D for all 19 AF points and mapped them. Since much of this was new information for me, and I have had my camera for more than a year, I thought it was worth showing, since many others likely do not know this either.

http://blogs.stonesteps.ca/showpost.aspx?pid=54 7D indicated vs actual focus points

I think that most of us in a vague way understand that the actual cross type focus sensors extend beyond the boundaries of the little square viewfinder focus box somewhat. However, some new things things that his measurements taught me were:

  • 1 That the actual sensor extends in some cases much further than I would have thought
  • 2 That often the actual focus sensor is asymmetric with one side significantly longer than the opposite side.
  • 3 That on some AF points the cross type sensor actually extends well onto a neighboring point.
  • 4 That the top and bottom two sensors of the diamond use the same vertical bar, making continuous horizontal detection across both AF points.
  • 5 That the extra wide column space just inside the left most three points and the right most three points is a complete blind area with no actual focus point extensions in these two columns. This would make tracking handoff from the center to the two ends of the diamond much more difficult.

The black rectangle on his illustrations represent the point at which focus was lost and show where the actual end of the cross type sensor is. So the cross extends from the inner edges of each black rectangle across the red focus point square.

You can see each focus point and the actual boundaries by mousing across the numbers at the bottom of the third illustration. Additonal information is in the comments at the bottom. He indicates that this was not unique behavior for one camera, but that several 7D's all did the same thing.  Very eye opening.

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kind regards
Dale

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