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Aperture Explained

 12th Aug 2020

Aperture is one of the most important tools to understand in photography. I have a handful of foundational controls I expect every budding photographer to understand and aperture is definitely one of them. As always, the best way to test your knowledge is to get out there and practice. Read this blog and once you have a better idea of what aperture is and why it’s important, get out there and practice.

I’ve broken this up into sections so it’s easy to follow and to put into action. This is what you will learn from this blog:

  • What aperture is
  • What aperture priority is
  • Aperture and F-stops
  • Aperture and shutter speed
  • When to use aperture priority

What is aperture?

Simply put, aperture is the opening where light passes through in your camera. It’s how you control your exposure. This is done in F-stops, we’ll learn more about them a bit later.  Aperture is a little backwards so it’s easy to get confused!

The lower the F-stop, the larger the aperture and the higher the F-stop, the smaller the aperture. The lower the F-stop the blurrier the background because the depth of field is smaller. The higher the F-stop the sharper the background because there is a bigger depth of field. 

Aperture is important technically for exposure and creatively for depth of field. Definitely a key part of basic photography skills.

What is aperture priority?

Aperture priority lets you manually set the aperture. It is often referred to as A or AV (aperture value) on your camera. This nifty mode gives you full control of aperture which means that it is up to you to pick the right F-stop for depth of field etc. It’s semi automatic and really fast to use.

When you set aperture priority you’re telling your camera that the aperture you’ve set is the most important thing because you’ve chosen it for a reason. The camera will then go and find a shutter speed that supports your choice of aperture, more on this a bit further on.

Let’s look at some features of apertures.

Wide apertures

  • Wide apertures are low numbers like 2.8 or 4 or 5
  • They give you a shallow (small) depth of field - good for fuzzy backgrounds or foregrounds
  • Careful focusing is very important to make sure the bit you want sharp is sharp
  • Because they’re ‘wide’ more light gets in so your camera in aperture priority will set a faster shutter speed

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Small apertures

  • Small apertures are high numbers like 16 or 22 or more

  • They give you a deep (big) depth of field ­- good for landscapes and scenery

  • Focusing not quite so critical ­- rule of thumb is go for a midpoint

  • Because they’re small less light gets in - so your camera in aperture priority will set slower shutter speeds. Use a tripod to avoid blurry pictures caused by camera shake.

Aperture and F-stops

F-stops are back to front. You have a big hole which lets in loads of light which is the wide aperture. This is a shallow depth of field. When the hole is small it lets in minimal light which is the small aperture. This is a wide depth of field. 

For example:

  • f3.5 = shallow depth of field
  • f11 = middle depth of field
  • f22 = masses of depth of field

Aperture has a massive impact on exposure and a creative impact on depth of field so it’s really important that we know how to set the aperture we want in AV mode.

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Aperture and shutter speed

Aperture and shutter speed need to work together;  if you change one you have to change the other. This is because they are in a reciprocal relationship. If we make the aperture smaller we need a longer shutter speed to compensate for the exposure. However, if you want to use a faster shutter speed you want a larger aperture to make sure there is enough light. If you use aperture priority then the camera will find the right shutter speed for you. But if you use shutter speed priority (TV) then the camera will source the best aperture.

When to use aperture priority

Aperture priority is very versatile so you could use it almost all the time. If you need a slower shutter speed - just set a smaller aperture and the resulting loss of light will force the camera to set a slow one. The opposite applies too. Set a wide aperture and more light gets in through the lens so the camera sets a faster speed to compensate. 

I like using aperture priority for:

  • Landscapes
  • Macro
  • Portraits
  • Weddings
  • Motor sport

Don’t be afraid to try different modes on your camera. It gives you a wonderful opportunity to hone your skills in a specific setting by giving you more control. 

Aperture is a critical skill we should all be familiar with and eager to learn more about. This is what helps us control exposure and gives us so much creative freedom with our photography.

If you need more focused training on the core functions of your camera then enroll on my ultimate beginners course. This course was designed to help you:

  • Feel in control of your camera
  • Know how to get the "Wow Factor"
  • Capture beautifully composed, well lit and exposed images
  • Be confident and feel creative
  • Save money for great locations - instead of useless gadgets

You can take your photography to the next level with the right foundational skills!

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