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Learning The Basics of Exposure

Exposure is often considered to be the ever elusive holy grail of photography; an aspect where most amateurs fumble and some even make an ungodly mess.

Most experts will tell you that there is no way to click professional quality pictures unless you have in depth information about what exposure is; how to use it for your benefit and the type of exposure needed for the various lighting conditions.

So, if you are trying to learn the ropes of photography, here is a look at what exposure can do for you.

What is exposure?

To put it simply, exposure is the amount of light that enters the camera through the lens as the shutter opens and closes. Exposure comes into the picture only when you choose to venture out of the safe auto mode of a DSLR camera and into the manual mode that will let you experiment to your hearts content.

The triangle of exposure

Triangle

Depth and dimension are determined by three elements: shutter speed, the aperture and the ISO. Used in combination they determine an image’s ideal exposure. Bear in mind that each of these elements impacts your photo in a different way.

If you were to learn about how these factors can together have a bearing on the exposure, a popular metaphor for elucidating the concept is to imagine the shutter as the window to a room, so the amount of light that filters in to the room will depend largely on how much and how long you keep the shutters open.

On the other hand, the aperture can be likened to the size of the window; the greater the size, the higher will be the amount of light entering the room. Finally, in order to understand the concept of ISO, imagine that you are wearing sun glasses inside the room, so ISO is the sensitivity that you display to the light entering the room. With the shades on, you will not be particularly sensitive to the sunrays entering the space; this would mean that you currently have a low ISO setting.

Shutter Speed

shutter

Shutter speed determines the amount of time the shutter is open and therefore how motion is captured. The longer you leave the shutter open, the more light comes in.

The shutter speed is measured in seconds; in most types of cameras and photography, you will be using a shutter speed of 1/60th of a second. This is because you will need to use a tripod for anything slower as there is a strong likelihood of the camera shaking as the shutter is still open giving you blurry images.

In most cameras, the shutter speed will double as you move up; so you will have access to the following speed range: 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500 etc.

shutter_illustration

The doubling is also a good way to remember that a decrease in the shutter speed will double the amount of light entering the assembly.

So, if you were to increase the shutter speed by one stop, you would get the same results as decreasing the aperture by one stop.

A low shutter speed works well when capturing images in dimming light; for instance dusk or night photography. When using a slow shutter speed; ask yourself how you intend to treat the motion in the image. For instance, you could freeze the movement or you could let it intentionally blur; adding more character to the image and depicting a sense of movement.

The focal length of the image will also have a bearing on the shutter speed that ought to be used. For example, since lenses with longer focal length are more prone to camera shake, you will need to use a faster shutter speed with them.

The ISO Setting

iso

The ISO determines your camera’s sensitivity to light. The lower the number, the less sensitive to light. Higher ISO settings are often used in darker scenes to get a faster shutter speed, but be cautious. As you move up the steps in ISO settings, the grainer the photo will be.

iso_illustration2

When choosing the ISO setting, you need to consider the following:

  • The amount of light available
  • The availability of a tripod
  • Movement in the subject
  • The amount of grain that you need in the shot

If you have ample of light and tripod and you need a picture with finer grain, you would want to go for a low ISO setting. A higher ISO setting would be more appropriate for shots of concerts, art galleries, indoor sports events, parties, indoor wedding shots etc.

The Aperture

aperture

The aperture is simply the size of the lens opening when a photo is snapped. A large aperture lets in more light. When you press the shutter release button, a hole opens up that allows your camera image sensor to catch a glimpse of the scene you want to capture. The aperture setting determines the size of that hole. The larger the hole, the more light gets in, and in reverse, the smaller the hole, the less light comes in.

Aperture is measured in f-stops, or f/numbers. For example f.2.8, f.4, f.8, f/22. Every one f stop you move up actually halves the size of the amount of opening in your lens. Lest you be confused, an f/22 is much smaller opening than an f/2.8.

aperture_illustration2

Keep in mind that a large aperture (smaller numbers) will decrease the depth of field, and a small aperture (large numbers) will give you a larger depth of field. This comes in handy when you get to a place where you want to shoot just the foreground in focus and have the background softer, or less focused.

The aperture setting will impact the depth of the image. For instance, you will need a higher aperture setting for taking portrait shots where you need your subject to be clearly defined while the background can be blurry.

On the other hand, for images where you need objects close to the camera as well as those that are far away from it in clear focus, you will need to choose a lower aperture setting.
It will also be worthwhile to remember that the only way to master aperture settings is to take out your camera and experiment with what you’ve got.

Conclusion

Mastering the fine art of exposure can prove to be a time consuming task not very different from juggling. As a matter of fact, it is normal for even experienced photographers to continuously tweak their settings to find the best setting for a specific shot.

Don’t expect to become an expert right away. There is only one way to become adept at finding the right combination, and that is with practice.

Now that you know the basics of exposure, continue reading about how to compose a good photo that makes you look like a pro.

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