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| p.9 #7 · p.9 #7 · Tamron 150-600 AI Servo sequential shots only |
Karl Witt wrote:
The key is 'it hunts' my Tamron on my 1DMKIII would simply STOP focusing and not try, hunt or even chatter without releasing then again pushing the focus button. Same problem even on a stationary subject when switching to another target while in AI Servo.
I really do believe that those who believe the problem is in the Tamron lens are really in denial.
The camera controls the lens, if the camera is confused for any reason, the lens cannot do anything, but hang.
In standard focusiing, the camera will not fire unless there is focus confirmation, the focus led lights up.
This means that there is some sort of feedback loop between the camera and the lens.
In AI Servo, there is no confirmation of focus lock. The camera will fire away, whether focus has been achieved or not. So there are two possibilies, the camera AF sensor has difficulty in assessing contrast, so cannot control the lens properly, or the lens is too slow in reacting.The lens seems to react perfectly well in standard AF (focus confirmation), but will not follow focus in AI Servo, simply because AI Servo makes greater demands on the camera AF and it seems that older Canon cameras, cannot satsify those demands when controlling a Tamron 150-600.
As I have said before, my combination of 7D and Canon 100-400 regularly show exactly the same problems that beset the 7D and Tamron 150-600 combination. In marginal or backlit situations, my setup just hangs and needs constant stabs of the focus button, to coax it into focussing, thereby missing the shot.
The whole issue should be resolved, when a Nikon and/or Sony version of the lens is released.