FWIW - I run El Capitan, I usually upgrade to the latest OS right away - have never run into a reason not to yet myself.

You might wish to take a look at several of the alternatives for Post processing work - Lightroom, Photoshop, Gimp, Dark Table, Rawtherapee, Capture One, Picasa, LightZone, View NX-2, View NX-I, Capture NX-D (View NX-2, NX-I & Capture NX-D are Nikon products) DPP (Canon)

There are a host of FREE and commercial products to replace the OS dependent freebies like Photos and IPhoto.

:thumbup: :thumbup: :thumbup:

Something else to consider which in the 7 pages in this post, no one has brought up. What settings are you using for AF-Area, Dynamic 1,11,21,51, how many Focus Points 11/51, Auto Area, 3D Tracking, and finally Focus Tracking with Lock On - short to long or off.

Back button focusing helps but is not critical to good focusing technique - I use both and get similar results.

For fast moving subjects, I either use Dynamic Area 21 or Auto Area. I have found that with the D800 3D Tracking is too slow for birds, but ok for athletes.

I keep Focus Tracking with Lock on between Normal and Short.

I use all 51 Focus Points - not just 11.

I will alternate between Focus and Release and just Release on AF-C Priority. More keepers with Focus and Release, but more missed shots as well. Birds against a clear sky or distant background work best for focus and release. Otherwise I will just use release.

AF-D vs AF-S - I have several AF-D lenses. I will often use an 80-200 F2.8 AF-D with a 1.4x TC to shoot sports - collegiate soccer, rugby and LaCrosse, - the D800's internal focusing drive is pretty fast and I feel that if I missed shots or did not acquire focus correctly it is usually my fault for not adequately anticipating where the action will be.

Looking at the work of many amateurs and professionals who come to me trying to do bird photography - the biggest issues are poor panning technique and settings other than what I have described. The will have 1 or 2 shots in focus in a sequence, with the other 15 or so out of focus. The other issue is relying on stabilization and using too low a shutter speed, too long on the Tracking so once they lose focus it takes too long to reacquire, too few focus points, and using a single point or Dynamic Area 51 point on AF mode.

With a little tweaking of these settings you can get better results.

If you Want the photo in Focus you turn the auto focus lock feature to OFF. In the Off position the camera will continue to focus as the subject moves... In the lock position is will stay in the same focus as the subject moves for the 1 or 3 or 5 second focus lock you have chosen. Focus lock Only works as the subject moves parallel to you, same distance away.. If the subject moves forward or backward your focus will be off until the camera refocuses at the 1, 3, 5 second intervals. Hope this helps.. PS I use the nikon D600 as well, absolutely no problem capturing BIF coming towards me or any other subject for that matter.