If you are an entry photographer that wants to improve your photo. There are three things you must fully understand- Aperture, Shutter Speed, and ISO. Let’s spend a few minutes to go through these important elements and make sure you know what you can do with them at your camera.

(1) Aperture

Aperture is located at the lens you are mounting on a camera. If you look through your lens carefully you may find some diaphragm blades inside. When these blades move, they can form a circle-like opening which is called the aperture. The closer the blades move, the smaller the aperture and vice versa. So obviously, aperture can control the amount of light entering the lens and camera. With a wider opening (blades move further apart), larger amount of light can pass through, just like a window. However, besides controlling the amount of light passing through, aperture has another useful function – control the depth of field, which we will cover more in another tutorial.

Commonly used aperture number: f/2.8, f/3.5, f/4, f/8, f/11 etc.

(2) Shutter speed

If aperture is like a window opening (wide or narrow), shutter speed is the “speed” we open and close the window. Provided the size of the window is fixed (the amount of light entering is fixed), the faster the window is opened and closed, the smaller amount of TOTAL LIGHT has entered the lens. You can find the shutter in your camera body.

Commonly used shutter speed: 1/60s, 1/100s, 1/200s, 2s, 8s, 15s etc.

(3) ISO

After understanding Aperture and Shutter Speed, here comes the last but not least element – ISO speed (or ISO). ISO is easy. Just remember – the higher the ISO, the more sensitive to light the camera is. That means if the aperture (e.g. f/8) and shutter speed (e.g. 1/200s) are fixed but the photo is under-exposed (too dark), we can increase the ISO to a higher value like ISO400, ISO800 and so on until the photo has a desired brightness.

Commonly used ISO value: ISO100, ISO200, ISO400, ISO800, ISO1600 etc.

One question: Why don’t we always use higher ISO like ISO400, ISO1600 etc so to make sure the camera is sensitive enough to light?

The answer is simple: The higher the ISO, the more “noise” the photo will have. These “noise” will make the image blur and severely decrease the quality. That’s why it is always a good idea to keep the ISO value to the lowest acceptable value in order to have the best photo quality and sharpness. That said, photography beginner should not be afraid of using high ISO when you NEED TO – for example taking hand-held photos in the dark or shooting star photos. You will learn more on how to use it wisely when you start to take photos on different topics.


In case we need to take a photo with exposure of 10 unit. There are many combinations on aperture, shutter speed and ISO.

For example:

  1. Use 1 unit of ISO, 1 unit of aperture and 10 seconds of shutter speed (1 x 1 x 10 = 10)
  2. Use 2 units of ISO, 2 units of aperture and 2.5 seconds of shutter speed (2 x 2 x 2.5 = 10)
  3. Use 100 units of ISO, 1 unit of aperture and 0.1 seconds of shutter speed (100 x 1 x 0.1 = 10)

So you can see from above examples, to generate the same amount of exposure value, different ISO, aperture and shutter speed combinations can be used.


After understanding the 3 most important elements in photography, all beginners should know how a photo is formed. However, you still need to practice and learn how to adjust these 3 elements to make the perfect exposure under certain circumstances. An easy method, and recommended to all beginners, is to use Aperture-oriented Mode a.k.a A-Mode or Av-Mode to take photos. Jump to our next article on A/Av-mode to learn more!


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Author: Alex Tam