Beginners guide to digital Camera Apertures

How and Aperture works

If you have any kind of camera with manual settings, one thing you should master is how to use the aperture setting properly. It's probably the most important thing to understand if you want to take great photos. The Apertur priority mode is often abbreviated A or Av (for Aperture value) on a camera mode dial and it's arguably the most important mode for most users who move on from the automatic mode.

Here is a super quick guide for those who are short on time and need to get up and running with the aperture and Apertur priority mode quickly.

Apetures open and closedAperture background:

Cameras need light. For a great Photo, the more the better.

The aperture and the shutter speed together control how much light enters the camera (and reaches the sensor).

To let more light in the aperture must be larger (more open).
To let more light in the shutter must stay open longer (the longer it is open the more light can come in).

The amount of light which shines on the sensor (in old times, the film) is called the exposure. Over exposed means too much light was let in, under exposed means too little.

So; To take a great picture you need the right exposure. But a good picture might (depending on the type you want to take) also need to be completely sharp (in focus). There are two parts of the image which we talk about when referring to sharpness:
a) The part that is correctly focused via the focus ring (or your cameras autofocus). This is called the focal point.
b) An area a little bit either side of the focal point. This is called the depth of field. With larger depth of field, the more foreground and background will be sharp.

One important note. You can also make the camera more sensitive to light to help in low light situations. This is done by changing the ISO. The ISO represent the sensitivity of the sensor, the higher it goes, the more sensitive to light the camera is. At high ISO's however, noise will start to be visible which can ruin your image. As a beginner, I recomend you master the shutter and aperture first. Learn how to get as close as possible to the right shot by only changing these two things. In extreme low light, just remember, you can increase the ISO. You will have to do your own tests to see how noisey you photos will be with high ISO. As a general rule, try no to go over 1600 ISO.

How the aperture and shutter speed affects burr/sharpness:

To make more of the image sharp, you need a larger depth of field, this means closing the aperture which will let in less light. This must be compensated by opening the shutter longer.

It works like this:

Aperture more open = more light comes = faster shutter speed. The faster the shutter opens and closes (the shutter speed), the sharper moving elements in the photo will be and the less affected the image will be by you shaking the camera as you take the photo. There will also be a smaller depth of field, meaning only those things directly in focus due to the focus ring will be sharp (background and foreground will be blurry).

Aperture more closed = less light = leave the shutter open longer. The slower the shutter speed, the more blurry the photo will from you shaking the camera and objects which are moving will be burry aslo. There will however be a larger depth of field, so on a tripod, and with no moving objects in the scene, overall the image will be sharper (background and foreground will appear sharper).

Summary, a general rule of thumb/guide for taking photos:

For an overall sharp photo:

  • Fast Shutter Speed
  • Closed aperture

For a photo with point focus (out of focus foreground/background):

  • Fast shutter

For a sharp action photo:

  • Fast shutter

Action shot with point focus
Fast shutter
Open aperture

For an overall sharp photo in low light:

  • Slow shutter + Tripod
  • Closed aperture

For a photo with point focus in low light:

  • Slow shutter + Tripod
  • Open aperture

Hope that helps!

Posted in You too can (how to articles)