how to
photograph
wild birds

Mastering brightness with the ISO speed setting

I understand the settings of the Tv and Av modes, but my pictures come out dark or blurry. You can solve these problems by adjusting the image sensor's sensitivity to light.

Black-tailed Godwits

This photo was taken in the evening with the sun hidden behind clouds as it was beginning to get dark.
The black-tailed godwits were walking around and pecking the mud looking for food. By increasing the ISO speed to ISO3200 and setting a relatively fast shutter speed of 1/250 of a second, I was able to freeze the motion of the bird's head.

Image data

Aperture value: f/11
Shutter speed: 1/250 second
ISO speed: ISO3200

Exposure compensation: 0
Focal length: 700mm
DSLR Camera (APS-C image format)

Brightness is controlled by the aperture (f/number), shutter speed, and ISO speed

When the aperture (f/number) and shutter speed are changed, the brightness is automatically adjusted. By increasing the ISO speed, it is possible to shoot in dark locations as well.

What exactly is ISO speed?

The ISO speed numerically represents the image sensor's* sensitivity to light. The ISO speed should be set to match the brightness of the shooting location. The benefit of increasing the ISO speed is the ability to use fast shutter speeds even in dark locations. The disadvantage is that image noise (which can make a picture look grainy) becomes more noticeable. Conversely, with a lower ISO speed (indicated by a smaller number), you can take high-quality photos with reduced image noise, but camera shake can become a problem in low-light shooting conditions since a slower shutter speeds must be used.

* The image sensor is the component that converts the subject's brightness and color into electrical signals. It is sometimes called an imaging element or a sensor.

Comparison of different ISO speed settings

What is the effect of a higher ISO speed?

Increasing the ISO speed allows you to use faster shutter speeds, which can minimize the blurriness caused by camera shake or subject movement. However, using a higher ISO speed results in more noise. Let's examine the relationship between ISO speed and noise. The higher the ISO speed setting, the more sensitive the image sensor becomes to light.

Relationship between ISO speed and shutter speed

1 Set your camera to Av (aperture priority AE) mode.

2 Turn the dial and set the aperture. Generally I would shoot at a lower f/number, but to highlight the effect of ISO speeds, I have set the f/number to a fairly high f/11.

Turn the dial to set the f/number to f/11.

It is easier to adjust the ISO speed by looking through the viewfinder

3 Set the ISO speed

Turn the dial to select AUTO while pressing the <ISO> button, then press the <ISO> button again

ISO speed: ISO200

With an ISO200 setting, sensitivity is relatively low. As a result, the shutter speed must be slowed down to capture a sufficient amount of light. The slower shutter speed, however, results in a blurry image due to camera shake and the movement of the subject. Due to the blurriness, we are not able to confirm the high graininess under the low-sensitivity shot.

Aperture value: f/11
Shutter speed: 1/15 second
ISO speed: ISO200

Exposure compensation: 0
Focal length: 700mm
DSLR Camera (APS-C image format)

ISO200

ISO speed: ISO3200

At this setting, I'm finally able to freeze the motion of the bird's head, but a certain amount of noise is noticeable.

Aperture value: f/11
Shutter speed: 1/250 second
ISO speed: ISO3200

Exposure compensation: 0
Focal length: 700mm
DSLR Camera (APS-C image format)

ISO3200

ISO speed: ISO16000

The photo looks sharp because the motion is perfectly frozen. But due to digital noise, it is hard to distinguish the detailed patterns of the bird's feathers.

Aperture value: f/11
Shutter speed: 1/1250 second
ISO speed: ISO16000

Exposure compensation: 0
Focal length: 700mm
DSLR Camera (APS-C image format)

ISO16000

For this scene, an ISO setting of 3200 yields the best results.

Usually, I would lower the f/number so I can shoot at a fast shutter speed without having to increase the ISO speed as much. It's important to consider how noise might affect the image, and think about what you want to portray when adjusting the ISO speed and shutter speed.

Note: The amount of noise that occurs at a given ISO speed varies between camera models. Therefore, shooting with the same settings on a different camera may result in different noise characteristics. Some cameras also have a high ISO speed noise reduction function.

Comment from a learner

I tried to photograph a species of little grebe using a small spotlight in a dark interior zoo environment. I set the mode to Tv (shutter priority AE). Despite being a bit grainy, I was pleasantly surprised by the brightness and high quality of the photo.
Camera settings: Tv (shutter priority AE) mode + ISO speed ISO12800 + exposure compensation -1

Little Grebe, by a learner

Aperture value

f/5

Shutter speed

1/320 second

ISO speed

ISO12800

Exposure compensation

-1

Focal length

105mm

DSLR Camera (APS-C image format)

Message from Mr.Tozuka

The student used an ISO speed setting of ISO12800 for this shot. But if the setting had been just a little higher ISO speed, the motion of the subject could have been better captured. With high ISO speeds, it's possible to shoot in dark buildings like this or at night without the need for a flash.

how to photograph wild birds