What is exposure?


The amount of light that reaches your camera’s sensor affects the exposure of your image. Generally speaking, a well exposed image is one that doesn’t contain too much white (overexposed), or black (underexposed). This can be controlled by three settings on your camera that work in unison:

1. ISO

This changes the sensitivity of the camera’s sensor. In darker conditions, higher ISO values will lighten your image. In brighter conditions, lower ISO values will prevent your image becoming overexposed.


2. Aperture

This determines the size of the opening through which light enters the lens. Setting the aperture to a lower value allows more light in, and setting it to a higher value restricts light. 


3. Shutter Speed

The shutter is like a curtain in front of the lens. The sound you hear when you take a photo is the shutter opening and closing to let light in. You can control the shutter’s speed, from seconds to fractions of a second, to adjust exposure.


These settings are like spinning gears and cogs - change one and it will impact the other. The most important thing you can do is practise and build a hands-on understanding of how they complement each other.

Keep in mind the look you are aiming for - if you are capturing motion, prioritise shutter speed and then adjust one or both of the other elements. For prioritising depth of field, adjust the aperture first. For more detailed information on your camera, book onto one of our photography courses.


City Academy run photography classes across London - practice your composition and get hands-on practical advice from professional photographers in our wide range of courses:

- Digital Photography for Beginners
- 5 Day Photography Summer School
- London Street Photography
- Portrait Photography
- Fashion Photography
- Documentary Photography
- Food & Product Photography
- Photoshop for Photography