Marcus Hawkins
Reveals how to use aperture to control exposures
The aperture is the opening in the lens. This opening is formed by a series of five to nine diaphragm blades that can be made to open and close to increase or decrease the amount of light that passes through the lens.
You can adjust the aperture on some lenses. In fact, rotating a ring on the lens was the standard way of changing the aperture until fairly recently. For example, Nikon debuted its AF-G lens line – featuring its first autofocus lenses without aperture rings – just 14 years ago. Some mechanical lenses still rely on an aperture being changed on the lens, but the majority of autofocus lenses require the aperture to be changed electronically on the camera body. This has numerous Lenses are referred to by the maximum or largest aperture they offer, such as a 50mm f/1.4 lens or a 70–200mm f/2.8 lens. Those that have very wide apertures for their focal length are described as ‘fast’ lenses. This is because their maximum apertures let in lots of light, enabling the use of fast shutter speeds and shorter exposure times. A 50mm f/1.4 lens is faster than a 50mm f/1.8 lens. Zoom lenses that have a range of f-stop numbers in their description, such as f/4–5.6 have what’s known as a ‘floating’ aperture. This means that the maximum aperture gets smaller as the lens is zoomed. A 100–400mm f/4.5-5.6 lens will offer a maximum aperture of f/4 at 100mm, reduced to f/5.6 at 400mm. advantages, such as enabling you to adjust the size of the aperture in smaller increments for finer control, and setting the aperture remotely on a Wi-Fi-enabled camera.
Aperture is an essential component of exposure because it regulates the amount of light that reaches the camera’s imaging sensor. Using a wide aperture to take a picture means that you’ll be allowing more light to reach the sensor, while a narrow aperture reduces the amount of light let in. In principle, it works the same way as the pupil in your eye. In the dark, your pupil dilates to let more light in, and in bright conditions it contracts. When it comes to photography, the more light there is, the shorter the exposure times can be, allowing you to freeze moments in time and improving the chances of getting sharper pictures.
Wide apertures can lead to exposure times that are short enough to take sharp photos of moving subjects, but they also reduce the depth of field – the amount of front-to-back sharpness – there is in a picture. For everyday photography this may not be an issue, and in fact it can be a real advantage, enabling you to separate