wasn’t enough to render the entire subject
sharply was because:
- The plane of the wing and body feathers
was about two inches closer to the camera
than the plane of the head. That was enough
to require additional measures for depth of
field.
- The depth of field of a 500mm lens is ex-
tremely shallow, especially at a relatively close
range. Had the bird been 75 feet away (and
obviously smaller in the frame), the DOF
wouldn’t have been a problem.
- The lens aperture was too large given the
critical loss of DOF due to the long lens and
the distance from the bird to the camera.
What should I have done? I didn’t want to
change the lens, and I couldn’t change the
subject--camera distance. Therefore, the
only variable I had at my disposal was to use
a smaller f/stop. How small? In this scenar-
io, f/11 would have been very good, but f/
would have been better.
However, my ISO was already 2000. An ap-
erture of f/11 -- two stops smaller than f/5.
--would have necessitated an ISO of 8000.
For f/16, the ISO would have been 16,000!
So, what to do?
Here are the options:
- If you have time, move back and refocus.
Then, in post-processing, crop the image.
This will give you more DOF, but the image
quality suffers.
- Raise the ISO so you could use f/11 or f/16,
and then in post-processing use Neat Image
software to eliminate the noise.
- If you have time, take two shots. First, focus
on the feathers and shoot. Then refocus on the
head and shoot again. In post-processing, put
the sharp head on the sharp body.
- Accept the shallow depth of field with the out
of focus head.
Real world DOF scenario #
I took the picture of the Torres del Paine Massif
in Patagonia on page 5 at sunset. Like the male
honeycreeper photo I just discussed, I used a
500mm telephoto to create a tightly composed
image of the dynamic peaks. Unlike the picture
of the bird, though, where depth of field was very
relevant, the landscape image could have been
taken at any lens aperture -- from f/4 to f/22 --
and the results would have been the same.
Why? Because the mountains were so far away
(I estimate 8 miles) that depth of field was com-
pletely irrelevant. All lens apertures would pro-
duce the identical picture you see here.
In a situation like this, where the lens aperture
doesn’t matter in terms of DOF, I choose the
sharpest aperture which is typically one or two
f/stops down from wide open. The largest aper-
ture on the Canon 500mm telephoto is f/4, so I
used f/8 for this shot.
Real world DOF scenario #
The leopard shown on the next page was so
close to my safari vehicle that I switched to a
24-105mm lens, and I took this composition at
70mm. This obviously gave me a lot more depth
of field than a long lens. However, because I was
so close (about 15 feet) from the cat, and my fo-
cal length was slightly in the telephoto range,