7d + 100-400 AF problem AI Servo - pls comment

Started Nov 9, 2009 | Discussions thread
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Jackson22
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7d + 100-400 AF problem AI Servo - pls comment
Nov 9, 2009

upgraded fr 40d for it's much improved af. lately, feedback on af in this forum had improve or shall i say proved it's prowess. i am interested in birding (main reason for the upgrade) but had a chance test the af of my new 7d in my kids succer game. weather was dreadful.

contrary to most of reliable people who used them on sports, my cam seems to jump focus on subject that suddenly appears in front of main orignal target. cam settings are c fn III-1 @ slowest; c fn III-2 @ 0; c fn III-3 @ 1; c fn III-4 @ 0. centre focus pt w/ expansion & aslo upper right pt w/ expansion. this settings are from tips from users here & this makes sense.

below are some shots that shows focus changed when obstruction appears in front which should have been ingnored. i also notice/seeing from viewfinder in more than 10 occasions(no exagerations) that focus change on all instances to front obstruction/s. be it slow walking pace or fast running pace they all switch focus to front obstruction! is it maybe my cam is defective or 100-400 is an older lens so it is not functioning properly. i will yet try my 400 f5.6.

here's 2 sequence shots I took yesterday.

focus finely switched to #8 kid in front

see the hand on right side on the kid who will obstruct on next sequence

boom! focus on front obstruction & he's even far from focus point

refocus back to original subject but it back focuses, fence & leaves are sharper.

any comments/help will be appreciated.

tks in advance.
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jackdshutter from surrey bc
http://www.flickr.com/photos/31701616@N00/collections/72157606198037633/
40Dee + 1oo-4oo + 4oo f5.6 + 24-105 + Tok's 11-16
580exII + better beamer + jobu LW2 gimbal + lee 6X4 grad ND set

 Jackson22's gear list:Jackson22's gear list
Canon EOS 7D Canon EF 400mm f/5.6L USM Canon EF-S 10-22mm f/3.5-4.5 USM Canon EF 100-400mm f/4.5-5.6L IS USM Canon EF 24-105mm f/4L IS USM
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