Aperture is a round shape diaphragm in the lens that determines the size of opening for the lens and the amount of light going into the sensor of the camera. As it controls the light going in, it greatly affect the exposure and depth of field of the photos. Hence if you need more light for exposure, then the aperture has to be set to a large number. Contrary, if less amount of light is needed for exposure, then the aperture can be set to smaller number.

The aperture is calculated by referring to the aperture F-number and f-stop. F-number goes by,
f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/46

With each step down from f/1.4 to f/2 and all the way down to f/64, the aperture surface is reduced by halved in each step. The aperture diameter or the diaphragm is reduced by a factor of 1.4 in each step.

Each stage is considered a stop. Hence f/2 is a stop lower than f/1.4, f/5.6 is two stop lower than f/2.8 and so on. The aperture f-number basically means the size of the opening with f/1 having the biggest aperture and the most amount of light going into the sensor. The lower the f-number means the smaller aperture size and fewer amount of light going into the sensor.

For every stop of the aperture, the amount of light going into the sensor dropped by half. For example, the amount of light going in with f/5.6 is half of the amount light going in with f/4.

    Lens aperture at F/4                                                   Lens aperture at F/16

The aperture size of the lens is printed on the lens barrel, for example aperture size of f/1.4 is written as f/1.4 or F4 or 1:4. The larger the aperture size of the lens means the bigger the opening of the lens, and subsequently this also means that the bigger the size of the lens and the higher the cost.

Lens with large aperture proves to be a very good tool especially in low light situation and capturing fast moving objects. Due to the large opening of the lens, even in low light environment, larger amount of light goes into the lens to achieve sufficient exposure compare to smaller aperture lens. Lens with large exposure is also consider as a fast lens, with the large opening, it can achieve sufficient exposure with faster shutter speed compare to smaller aperture lens. With so much usefulness, large aperture lens comes in a big size and huge price.

Other than affecting the exposure, the size of the aperture also affects the depth of field. Large aperture will provides shallow depth of field and small aperture will provides larger depth of field. It simply means with large aperture setting, the distance whereby the object looks clear and sharp is short whereas with small aperture, most of the object in the photos will be clear.

    Up close on the aperture blade.


More about Camera Setting


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