V1.02
Thom Hogan’s Complete Guide to the Nikon D300
Page 392
bodies, this was only available with the multi-function back,
while in others it was available through custom settings.
Trap focus is a situation where you
pre
focus on a particular
spot and no picture is taken until something occupies that
spot and is noted as being in focus. For example, you focus
your camera for the finish line of a race. But until someone
hits the finish line and is seen by the camera to be in focus,
no picture is taken. The moment that first racer does hit the
finish line, click, your picture is taken.
You can mimic trap focus on a D300 (Custom Setting #A2
cannot be set to
Release
):
1.
Set Custom Setting #A5 to
AF-ON Only
.
2.
Set the Focus mode to Single Servo.
3.
Set the Autofocus Area mode to Single Point.
4.
If the lens has a focus switch on it, set it to
A
(Autofocus; on some lenses this is labeled
M/A
).
5.
Pre-focus the lens to a particular distance.
6.
Press and hold the shutter release. The camera shoots
when the selected focus bracket is in focus
(remember, you can also use the
AF-ON
button to
focus).
Autofocus Assist
The D300 has the dreaded built-in Autofocus Assist lamp of
the consumer cameras to help the camera focus in low light
situations. Unfortunately, it’s generally more hassle than it’s
worth:
• The location is poorly chosen.
If your hand doesn’t block
the light, the lens usually does the job. The D300 manual
lists a number of lenses that block the sensor for distances
shorter than 3’ (1m), but in practice I’ve found that
optimistic; more lenses block the sensor than Nikon
claims, and if you use lens hoods the situation is worse.
