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Exposure Triangle Basics

Aperture, ISO, and shutter speed are the backbone of any photographer's knowledge. Understand how to use these functions properly and you'll be able to switch off auto to more advanced settings and get the best out of your Digital SLR camera.

What is aperture?

Ap eture controls the amount of light your DSLR allows into the exposure by measuring the lens hole width. This allows you to control the amount of light that is feeding into your image. Aperture values are expressed in numbers called f/stops – the smaller the f/stop number means the more light that is coming into the camera.

Example: f/1.4 lets in more light than f/22, which is like a pin hole.

Apart from controlling the amount of light into the exposure, aperture is also used to change the depth of field (blur in the background).

A smaller aperture, like f/1.4 lets in a lot of light, compared to f/22 which is like a pin hole.

What is ISO sensitivity?

ISO sensitivity measures how your DSLR detects light.Changing the ISO allows you to change the sensitivity of the sensor on your camera. The higher the ISO number, the more sensitive to light the sensor in the camera is, and is generally used in darker environments to get faster shutter speeds. ISO values double with each increase in light sensitivity, so the lower your ISO value, the more detail you'll get in your photograph.

As a general rule, use higher ISO value like 800 in a dark setting, and when you are outside on a bright sunny day, use a lower setting like 100 or 200.

What is shutter speed?

Shutter speed measures how long your camera shutter, and how long the digital sensor on your camera is exposed to light. Shutter speed is measured in fractions of a second, and the larger the number, the faster the shutter speed. Faster shutter speeds (i.e. 1/2000 of a second) are generally used to freeze fast motion subjects.

Slower shutter speeds (i.e. 1/30 of a second) are generally used in low light situations and deliver richer detail and colour. Each interval doubles the time the shutter speed is open for (i.e. from 1/1000 of a second to 1/500 of a second to 1/250 of a second). Daylight shots are optimal at around 1/125 of a second. To avoid camera shake for any shutter speed slower than 1/60 of a second, consider using a tripod or resting your camera on a stable surface

The photographer's secret: Don't shoot on a shutter speed that is anything less than 1 on the focal length of the lens.

Example: For a 250mm lens, only use a shutter speed of 1/250 of a second or faster, unless you have a tripod