Exposure For Beginners: An Introduction To Manual Modes

The digital camera makes it possible for anyone to snap a photo. Just point, and the camera chooses the settings. But, frankly, like any technology, it has its limitations, and a lot of them. Automated modes don’t choose the best settings for depth of field. They don’t allow for creative blur techniques. And in many instances, auto doesn’t even get the exposure right.

If you bought a DSLR or other advanced camera and haven’t yet ventured off of auto, you’ve wasted your money. Manual modes allow for the ultimate creative control—that’s something even a fancy camera can’t do for you. Ready to really get some use out of the hundreds you spent on that camera? Take full creative control over your photography with this introduction to manual modes.

What is exposure?

A digital camera works by exposing a sensor to light. Exposure, then, is how light or dark that image is, based on just how much light that camera sensor was exposed to. An overexposed image has too much light, or is too bright, while an underexposed image is too dark.

There are three camera settings that determine exposure: aperture, shutter speed and ISO.


Aperture is the size of the opening of the lens. Just like a large window lets a lot of light into a room, a large open aperture lets a lot of light into the image. If your image is too dark, opening up the aperture will help. Aperture is measured in f-stops, with small numbers indicating a wide opening. An f/1.8 is very wide, while an f/22 is a very small opening.

**shutter speed on a DSLRShutter speed **

Shutter speed** **is how long the sensor is exposed to light. A shutter inside the camera lens opens and closes each time an image is taken (the sensor is exposed to light when the shutter is open). Shutter speed is measured in seconds and fractions of a second. A three second shutter speed is very slow, while a 1/16,000 s. shutter speed is very fast.


ISO is just how sensitive the camera’s sensor is to light. A low ISO, like ISO 100, is not very sensitive light, which is perfect for shooting outdoors during the day but not so great for scenes with low lighting. A high ISO, like ISO 6400, is a big boost for taking photos at night.

Aperture, shutter speed, and ISO combine to form the exposure triangle; changing just one setting will affect the exposure, but you could also change a second or third setting to balance out the first change, resulting in the same exposure. But if the exposure was balanced in the first place, why change your settings?

What else can you do with manual modes?

Each setting also has an impact on another element in the image, besides just the exposure:

  • Aperture has a dramatic effect on depth of field, or how much of the image is in focus. A narrow aperture like f/22 will leave most of the image sharp, like in a typical landscape photo. A wide aperture, like f/1.8, will leave only a small part of the image in focus, resulting in a soft background, like in many portraits. A narrow aperture allows the photographer to include more details from the entire scene, while a wide aperture results in a soft background that draws more attention to the subject.
  • Shutter speed has a big impact on blur in an image. Anything that moves while the shutter is open will result in blur. Fast moving objects, like athletes and race cars, need a fast shutter speed. But sometimes blur is intentional. A slower shutter speed is used to blur the motion of a waterfall, for example. Slow shutter speeds are also used with techniques like panning and zoom burst.
  • ISO determines how much noise, or graininess, is in an image. Images shot at high ISOs have noise and can even loose some detail. As a general rule, it’s best to leave the ISO as low as you can, though high