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How to Use Aperture and F-Stops in Photography

"Come to me..." captured by Sean Nel

What is the aperture of our cameras? What is the use of setting a large or small one? Lets dive into those

mysterious numbers and find out what they mean. Think of the aperture as the opening of your lens. Light

arrives and its photons are focused onto the sensor by the lens. The incoming analog signal gets then

translated into digital numbers and written on the memory card.

Typical F stop numbers are: F1.4, F.1.8, F2, F2.8, F4, F5.6, F8, F11, F16, F22

As they get smaller, the opening in the lens gets larger. And vice versa.

The reason why this happens is because these numbers represent fractions of the diameter of the lens. For

example F2 means that the entire diameter of the lens gets divided by 2. If we have a 50mm lens and we

set F2 in the aperture settings, the opening of the lens will become 50/2 = 25mm. If now we set F4, the

opening becomes 50mm/4=12.5mm. So setting a higher F number we obtained a smaller opening.

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So whats the use of these numbers?

As we create small apertures, the depth of field increases. Depth of field is the range of the scene that stays

sharp and focused. As we set large apertures the depth of field decreases.

The amount of light entering the camera also gets affected. Small apertures bring less light into the

camera. Large apertures bring more.

Therefore small apertures are useful for landscape photographers because they can keep vast

extensions of space focused and sharp. However because less light is entering the camera, there is more

danger of camera shake producing blurry images. Thats why landscape photographers tend to use a

tripod to keep the camera firmly in place during the long exposures that they need to use to capture

enough light when they use small apertures.

Large apertures are useful for portrait photography, where you want to focus on the face of the subject

and blur the background to avoid it becoming a distraction. The small depth of field means that you can

keep in focus the head of the person and blur all the rest behind the subject. Because by using a large

aperture you are also bringing more light into the camera, large apertures are also easier to use without a

tripod.

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Photo captured by Edgar Barany

In Landscape photography small apertures are common. In fine art photography or commercial

photography all ranges are used although larger apertures are common as fine art photographers and

commercial photographers tend to work often in studios where the range of the scene that needs to be in

focus is smaller than those who work with landscapes.

Think of the aperture of your lens as the channel through which light enters your camera. Light is that

precious material of which the magic of your photos is made. With your aperture you can shape the

amount of that magic that enters the camera and by doing so you affect other parameters such as the

depth of field.