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Hack 26 Create the Maximum Depth of Field

Imagine the kind of pictures you could take if
everything were in focus from one foot to infinity?
Here's the inside scoop on one of the oldest secrets
in photography.

Galen Rowell,
one of my favorite photographers, used to create landscape
compositions in which both foreground objects and distant elements
appeared in perfect focus. The effect is stunning. The viewer can
both study a delicate pattern of petals in a foreground flower and
marvel at the beauty of outlying mountains. How did he do that?

Galen found a way to capture tremendous depth of field in his images.
In other words, he could have everything in focus, from inches away
to infinity. You can employ this same technique in your photography;
you just have to know the hack.

Three important factors come into play on these types of shots:

The focal length of your lens

The wider the better.

The lens aperture

The smaller the better (f-16, f-22, etc.).

The object on which you focus in the composition

Contrary to expectation, it's not the thing closest
to you.

Once you've properly set these adjustments, you can
create depth of field that spans from a foot in front of you to the
puffy clouds drifting by.

2.12.1 Focal Length: The Wider the Better

Wide-angle
lenses, or zoom
lenses set to
wide angle, are a key factor in depth-of-field photography. They help
create the illusion that more things are in focus.

Galen Rowell usually shot with 35mm film cameras, and often he would
use a 24mm wide-angle lens for this type of
landscape
image. For this hack, I recommend you find a digital lens that
provides a film-camera equivalent of a 28mm lens. You can go wider if
you want (such as 24mm), but as you'll see,
that's easier said than done in the digital world.

For example, if you're shooting with an SLR, such as
a Nikon D70, then
you would need to use Nikon's 17-55mm zoom lens to
get roughly the same angle of view as Galen's 24mm
lens on his 35mm SLR.

Why? Well, the D70 and many other digital
SLRs have image sensors that are smaller
than 35mm film. That changes the relationship between lens and
camera, and the result is that you often have to multiply the focal
length of the lens by a factor of 1.5 to get the same angle of
coverage that you would with the lens mounted on a film camera.

If you multiply the Nikon 17-55mm zoom lens by 1.5, you get the 35mm
equivalent of a 25.5-82.5mm lens. You may or may not care about all
of this. But what you do need to know is that you have to find a lens
with a film-camera equivalent of at least a 28mm lens for this type
of photography. The Nikon 17-55mm zoom on a D70 should work nicely.

If you're shooting with a digital
point and shoot, such as a
Canon
PowerShot A80, then your built-in zoom lens (7.8-23.4mm) has the
film-camera equivalent of a 38-114mm zoom lensnot quite as
wide as we'd like for this type of shooting. The
good news is that Canon offers a wide converter (WC-DC52) for this
camera that attaches over the built-in zoom lens. It extends your
field of view to a healthy film-camera equivalent 24mm lens. Cool!

In fact, many digital point and shoots accept wide-angle lens
attachments. If you're interested in this type of
shooting, then you'll want to make sure your next
camera has this capability.

No matter which route you choosedigital SLR or point and
shootget to the film-camera equivalent of a 28mm lens, and
you're in business. Scenes such as the redwood
forest shown in Figure 2-20 are captivating when
you're able to extend the depth of field to render
all elements in focus, from foreground to back.

Figure 2-20. Extending the depth of field in a redwood forest

2.12.2 Lens Aperture: The Smaller the Better

The second factor for extending your depth of field is to
use a small aperture. If we go back to the Nikon 17-55mm zoom, for
example, it has an aperture range from f-2.8 to f-22. When the
aperture is set to wide open (f-2.8), your
images will have a shallow depth of field. For this assignment, you
want to use the opposite (f-16 or f-22) for maximum depth. You can
achieve this by using the Aperture Priority or
Manual
Exposure mode on your camera. If you don't have
these modes available, look for Landscape in your menu of options. It
will stop down the aperture for you (stop
down is an old photography term for making the iris hole
smaller by choosing an f-stop such as f-16).

When you have the aperture closed down to a diameter this small,
you're usually going to have long shutter speeds,
such as 1/8 or 1/4 of a second, to compensate for the reduced amount
of light coming through the lens. These shutter speeds are too long
for handheld photography, so a tripod is in order.

If you attempt to hand-hold the camera with these long shutter
speeds, your pictures won't be sharp, due to camera
shake. The best way to avoid camera shake is to use a sturdy field
tripod and a remote shutter release, so as not to jar the camera when
you trip the shutter. You can use the self-timer instead, if
that's more convenient.

The main thing to remember is to steady your camera and stop down
your aperture to f-16 or smaller.

2.12.3 Set Your Focus Manually

Now, here's the real secret to success:
switch
to manual focus mode and focus on an object
that's one-third deep in the composition. Think of
it this way: if the flower is the closest object in the picture and
the mountains are the most distant elements, then manually focus on
something that is one-third the distance between them.

Your tendency will be to focus on the nearest objectin this
case, the flower. But that won't give you the
greatest depth of field. If you're shooting with a
digital SLR that has a depth-of-field preview, you can test this
theory. Set your camera to f-22 and focus on a point
that's one-third deep in the composition. When you
initially look through the viewfinder, both the near object and the
distant elements will appear out of focus. That's
because you're viewing them with the aperture wide
open, which shows the least amount of depth.

If you want to shoot a scene with a nice foreground object, such as a flower or pine cone, but you can't find the right composition, carry a few items with you. Bring your props from home and place them in the landscape as needed. Some photographers even cultivate indigenous plants specifically for this purpose.

Now, press the depth-of-field preview button (with the aperture still
set to f-22). The image will get darker, because less light is coming
through the lens. But if you look carefully, you'll
see that both the closest object and the distant elements are now
magically in focus.

2.12.4 Final Thoughts

Every lens and camera combination has its own quirks and
characteristics for this type of shooting. If you're
lucky enough to have a depth-of-field preview button, you can
actually check your scene before shooting. But even if you
don't, with a little experimentation
you'll discover that you can stretch the boundaries
of clarity to incredible distances. Save this technique for special
compositions that are enhanced by great depth of field.