"Swerve lens away from object, keep shutter fully pressed and aim lens back at prefocused object - snap"
Of course you have to move to a portion of the scene that's out-of-focus to fully depress the shutter. Then you move back to the prefocused area when the target you're waiting for comes into view. Snap...
#3. "RE: Focus trap for D7000" In response to Reply # 1 Sun 16-Dec-12 03:59 AM by Rmastran
I would add a few steps to this that work well for unattended setups.
Set the camera to continuous shooting (CL). Use a remote switch (such as this one: http://bhpho.to/URQIQm) to lock the shutter.
When the subject enters the focus area, the camera will start firing, and will stop when the subject leaves the focus area. When the subject re-enters the focus area, the camera will automatically start firing again.
#5. "RE: Focus trap for D7000" In response to Reply # 2 Thu 09-May-13 10:22 PM by km6xz
St Petersburg, RU
Another aid in successful trap shooting is to stop the aperture down a bit so is the subject is not a flat plane parallel to the focal plane. That increases the field depth so if the desired focus point comes into range after a leading edge at another focal plane is locked onto. For example if it was a person walking parallel to the focal plane and is swinging their arms in a natural gate, their far arm would trigger the shutter before the face or body closer to the camera would in focus. So calculate the Dof needed to assure the whole subject would be in focus if any part was able to trigger the shutter. Stan St Petersburg Russia
#6. "Must be on AF-C and AE-L/AF-L button assigned as AF-ON" In response to Reply # 4 Sat 16-Feb-13 10:33 PM by hyphotographer
I tried today after receiving my Neewer labelled 'Shoot' MC-DC2 remote switch from Amazon U. K. (£2.44) and like it very much. I pushed it to lock position after the 'pre-focus' and 'swerve lens away' procedures.
In addition, you must assign the AE-L / AF-L button to AF-ON, disabling the shutter release buttons (including remote MC-DC2) to initiate auto focus (AF).
Next, to let your D7000 work 'auto-firing', you must use AF-C, and set it to release on 'Focus' rather than 'Release', on page 208 of the D7000 English Instruction Manual (a1: AF-C Priority Selection).
If you use AF-S, it will fire regardless of your object is in focus or not, because the camera will only consider for once, the object appear in focusing point (tiny square), seen in the viewfinder is in focus or not.
Whereas in AF-C, the camera will continually considering your object appearing in the tiny square (focusing point) is in focus or not. As a result, when your object is not in focus, it will stop firing. D7000 will auto-fire again when object is in focus.
The D7000 manual does not give you this instructions, but fellow Nikonians help each other to figure out this trick.
#8. "RE: Focus trap for D7000" In response to Reply # 1
Farmington Hills, US
Note that Nikon changed the AF behavior with the D800 and D4 so that trap focusing is not possible. I don't know if this change extends to later cameras such as the D7100 and D600.
Gary in SE Michigan, USA. Co-organizer of the Southern Michigan Chapter Nikonians membership - My most important photographic investment, after the camera. D4, D810, D300, D90, F6, FM3a (black), FM2n (chrome) YashicaMat 124, Graflex Speed Graphic 4x5 My Nikonians Gallery & Our Chapter Gallery