AF results from my second 7D body

Started Nov 3, 2009 | Discussions thread
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AF results from my second 7D body
Nov 3, 2009

I received my 2nd 7D body on Friday. I still had my first 7D body (sent back today) and did some intensive body vs. body tests over the weekend. Here's a summary of my findings:

  • My second body has much more consistent AF performance. When testing both on static subjects and focus charts, the first body exhibits random front and back focusing with my 85mm 1.8 and 70-200 f/4 lenses for the same target. I do not see this anomaly on my 2nd body.

  • Event with the static AF improvements on the 2nd body, I still can produce sequences of photos which are misfocused, depending on the subject area underneath the AF point. Unlike the first body where the photos appear randomly front/back mis-focused, on the 2nd body I can get consistent misfocus for a static target when the AF point is aligned a certain way over the target. For example, one of my tests is a line of 5 soup cans staggered at various depths from the AF/focal point. If I focus on one part of the label, I get 100% tack-sharp photos for endless sequences of shots. If I focus on another part of the label, I get 90% OOF shots which no amount of MA can fix (focus point way off). To my eyes, both label sections have about the same level of contrast and alignment to the AF point so I'm confused as to why one part of the label gives me 100% focus and the other only 10%, esp. considering the camera locks onto to both immediately and both are on the same vertical focal plane from the camera. I understand that the actual AF sensor may not align perfectly with the displayed focus bracket but there's nothing near the bracket that the camera could be erroneously focusing on. I'm completely puzzled about this behavior.

  • Putting the chart/soup can focus issues aside, my "real-world" tests of natural targets shows the 2nd body is focusing quite well on static targets. The consistently level is very high though I still found a few targets that demonstrate the consistent OOF issue I see on the soup cans.

  • Relatively satisfied with the static focusing (for now), I ventured to try some servo focusing as well. I did this mostly for the benefit of other forum members because most of my shooting is static subjects and so I don't have much need for action/servo shooting (nor do I have much experience with it either). Nevertheless, I ventured to the dog park with my 70-200 f/4 to gauge dynamic AF focus. I used center point expansion with all the default custom AF servo settings. From this experience I learned that I really suck at taking action photos, at least for dogs running at blinding speeds in random directions. Still, for the shots I think landed on the dogs I got about a 40% keeper rate. I'll post full-sized photos in a reply to this post for those that want to skip it.

  • More to come as I continue my testing with the 2nd body.

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