need help tracking birds in flight

hi, i have a 1d mkiv with an 800 mm. im shooting distant birds in flight with auto iso, 8.0 ap, and about 4000 tv. center autofocus and surrounding pts to track. it seems like most of my shots at 100% are not sharp. when i focus close in the autofocus and lens is tack sharp. does anyone have this problem or can you tell me what settings you use for tracking birds in flight with this camera? thanks.

bimija wrote in post #13490230
hi, i have a 1d mkiv with an 800 mm. im shooting distant birds in flight with auto iso, 8.0 ap, and about 4000 tv. center autofocus and surrounding pts to track. it seems like most of my shots at 100% are not sharp. when i focus close in the autofocus and lens is tack sharp. does anyone have this problem or can you tell me what settings you use for tracking birds in flight with this camera? thanks.

Need example images.

Have you checked your depth of field? If you are tracking a f 5.6 with an 800 mm lens at say fifty to eighty feet your depth of field is quite often no longer then one foot making accurate focus extremely difficult. Things don't improve much at f 11. I track birds quite often with a 500mmf4 and a 1.4 TC giving me 700mm. I have more luck with large birds- birds that are not white offering more contrast to the AF system- and birds flying directly at me rather then accross the focal plane. I have never had much luck with expanded single point, rather I use single point only. Sample photos would help.

What's the background like in the images using the center point and outer points?