V1.02
Thom Hogan’s Complete Guide to the Nikon D300
Page 523
3. Just a reminder: just because you use the default doesn’t
mean that focus doesn’t get achieved. Still, this is an area
you need to practice with some subjects that are active to
understand. When you select
Focus
, the camera doesn’t
try to open the shutter until the AF mechanism has given
the camera feedback that focus has been achieved. When
you select the
Release
selection, the camera immediately
starts to open the shutter. If you’ve been holding the
shutter release partway, the camera probably already has
figured out focus and is tracking it. Even if you didn’t hold
the shutter release partway, in that short amount of time as
the button is going from midway to fully depressed, the
camera tries to figure out where focus is and has started to
move the lens. What I notice on the D300 is that it has a
slight and almost imperceptible lag in this respect that I
don’t see on some other Nikon bodies, especially if you’re
in one of the Dynamic Autofocus Area modes.
4. When I jab the shutter release fast with
Release
set I
sometimes don’t get in-focus shots (despite what I just said
in #3), while I
never
had this problem with the F5. I do
note that if I switch to Single Point autofocus or press the
shutter release in a more stately fashion, the number of in-
focus shots I get goes up (and, of course, holding the
release partway prior to pushing it all the way gives the
autofocus system plenty of time to figure out where it’s
going to try to focus).
5.
R focus
is an attempt to fix the problem of what
happens between shots, by making the camera pause
slightly between them if the subject is dark or the subject
low in contrast. The premise is that the camera doesn’t
have enough mirror-down time between shots, especially
at the 6 fps frame rate, and that in low light/contrast
situations the AF sensors aren’t as reliable with short looks
at the subject. Remember, the mirror has to be down for
the focus system to acquire data. If you’re having trouble
achieving focus at high frame rates, by all means try
R focus
, but be aware that your overall frame
rate likely slows. This setting is also useful in very low