2019-06-01 Outdoor Photographer

Manual Mode With Auto ISO
Not every camera offers a manual
mode with Auto ISO and exposure
compensation, but most of the newer
bodies do. I estimate that in 70 percent
of the scenarios I encounter, manual
mode with Auto ISO is my preference. It
lets me control the two parameters that
have the biggest impact on the look and
feel of the final image—shutter speed
and aperture—while still allowing the
camera to handle some of the work.
As a wildlife photographer, I typi-
cally think first about shutter speed. I
can choose a shutter speed fast enough
to freeze a breaching orca in the San
Juan Islands (around 1/2000 sec.) or
slow enough to produce a clean, low-
noise portrait of a mountain gorilla in
the low-light jungles of Rwanda. I can
do this rapidly with just one finger on
the command dial for shutter speed,
and the ISO will automatically follow
to maintain proper exposure. I also use
this technique for birds, lowering the
shutter speed for a portrait of a perched
bird and then quickly increasing to catch
the bird in flight.
Next, I think about aperture. Wildlife
photographers don’t drag huge ƒ/4 tele-
photo lenses through the jungle only to
stop them down to ƒ/11. We use those
lenses because we’re dealing with low-
light situations during the golden hour
or in the deep shade of the forest where
we need to shoot with the largest aper-
ture possible. When I have more light, I
might choose to open the aperture to get
background separation or bokeh, or close
it down to maximize depth of field for
an environmental shot. I want to be the
one making the aperture decision in all
of those scenarios.
Having chosen shutter speed and
aperture, I’m left with ISO, and in
this mode, the camera decides for me
instantaneously. Of course, a photogra-
pher’s experience and judgment are still
required to properly expose the image,
and that’s where exposure compensation
comes in. After I’ve selected my shutter
speed and aperture, and my camera has

set the ISO, I evaluate the scene and

decide if I need to adjust. If I have a

bright sky behind a dark subject, I can

quickly add a stop or two of positive

exposure compensation to ensure the

subject isn’t underexposed. Conversely,

if I have a white bird in direct sunlight, I

can set negative compensation to avoid

blowing out highlights and losing beau-

tiful feather detail.

My clients often fear shooting at high

ISOs and sometimes ask if they should

set a max ISO limit in their camera.

While lower ISO is always preferable,

modern cameras have remarkable high-

ISO performance, and post-processing

offers additional noise reduction options.

There are no options for fixing camera

shake or insufficient depth of field after

the fact—yet another reason to take con-

trol of the shutter speed and aperture.

I recommend against setting an ISO

limit. If you hit the max ISO, you can

underexpose significantly, and you risk

an unrecoverable shot.

Instead, I recommend simply keeping

an eye on the ISO in your viewfinder.

If it goes higher than you’d like, open

your aperture and/or slow your shutter

speed if the situation allows it, and the

camera will reduce ISO accordingly. For

example, every time you cut your shutter

speed in half, your ISO will decrease by

a factor of two as well. Try shooting at

shutter speeds as low as 1/10 sec. for

non-moving subjects in low-light scenar-

ios. If that’s not possible, I’m in favor of

letting the ISO go as high as necessary.

If a leopard steps into the open while

on safari in Kenya at twilight, I’ll take

a noisy image over no image at all any

day of the week.

Manual mode with Auto ISO gets my

exposure close to perfect most of the

time. With that head start, I can fine-

tune using exposure compensation. By

shooting this way, I have control of

the image but less to think about and

fewer steps. That translates into quicker

reaction time to capture the decisive

moment—an essential ingredient for

wildlife photography.

Breaching orca, San Juan Islands.

Manual mode with Auto ISO allows

you to quickly increase your shutter

speed to capture the action when it

starts. In this mode, you can maintain

proper exposure in one step instead

of two.

Mountain gorilla, Rwanda. Manual

mode with Auto ISO allows you to

quickly reduce your shutter speed

while maintaining your exposure with

one adjustment instead of two for

clean portraits of wildlife in low light.

PRO TIP: Manual with

Auto ISO and exposure

compensation shines in

those situations where

your subjects are erratic

and can start and stop

unpredictably. I also

choose it where light

levels are constantly

changing. Rather than

adjusting ISO for each

frame, Auto ISO does

the adjustment for you

and does it faster.

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