D4 Firmware 1.1 update and trap focus
I have been reading that this change is for trap focusing.
Firmware 1.1 update:
· When AF-ON only was selected for Custom Setting a4 (AF activation) and the AF-ON button was pressed to initiate autofocus during viewfinder photography, focus remained locked even after the user took their finger off the button, and the shutter could be released at any time. However, specifications have been modified so that the shutter cannot be released under the following conditions if the camera fails to focus.
· Autofocus mode is set to AF-S (single-servo AF)
· AF-area mode is set to Single-point AF
· Custom Setting a2 (AF-S priority selection) is set to Focus
So how exactly does one get this to work?
Set the settings with the 3 things described above than press the AF-ON to focus on the spot that you expect the subject to cross and release the AF-ON and keep the shutter pressed? When the subject crosses the point the shutter will fire?
Here's a one page article on it.
As he mentioned at the end, it works best for predictable action
Photography - It's a passion No other reason required.
With the AF-S setting as you describe you need to actually acquire focus at the desired distance before recomposing and waiting for your subject to then arrive at the desired point of shutter release- the trap!
It is easy to test before you head outside, focus on some object such as a chair, move camera slightly so as to have nothing at desired focus distance, press shutter and pan back to object of focus. Release will occur when the subject is at the preset (primed is the term in the previous link) distance.