1Ds MkIII vs 1D MkIV

[Joel Eade]

I just got back from short trip to South Carolina where I was able to spend about 4 hours taking bird images using the 1DX with the version I 500mm f4L + version II 1.4 TC hand held from a boat. I was having no problems locking focus on birds in flight quickly and no problem tracking either. I was using AI Servo and central point with expansion. It was very cloudy day requiring very high ISO but still no issue focusing or tracking even across complex backgrounds. I do have the focus function assigned to a button on the back so I can focus with my thumb and actuate the shutter with my index finger. I find it much easier to track objects this way. I realize this is not using AF at f/8 but using the back button for focus may be helpful as I have done the same thing using the 2 X TC version III and although it is slower the keeper rate is higher than when trying to keep a moving object in focus by using the half shutter press.