Setting the aperture in a camera primarily involves using specific camera controls while often looking through the viewfinder or at the live view screen. The exact steps can vary slightly depending on your camera model and the shooting mode you are using.
Here's a breakdown of how to set the aperture:
Understanding Aperture and Shooting Modes
Before you can set the aperture, your camera needs to be in a mode that allows manual control over this setting. The most common modes for controlling aperture are:
- Aperture Priority (A or Av): You set the aperture, and the camera automatically selects the appropriate shutter speed for correct exposure.
- Manual (M): You set both the aperture and the shutter speed yourself.
- Program (P): The camera sets both aperture and shutter speed, but often allows you to adjust the combination (Program Shift).
- Shutter Priority (S or Tv): You set the shutter speed, and the camera automatically selects the aperture. (Aperture is determined by the camera here).
For full control over setting the aperture, you will typically use Aperture Priority (Av) or Manual (M) mode.
Steps to Change Aperture
Once you've selected a suitable shooting mode (like Av or M), follow these general steps:
- Locate the Aperture Control: Look for a dial or button on your camera body that is designated for changing aperture values (often labeled 'Av' or related to f-numbers). This control might be a main dial, a sub-dial, or a button you hold down while turning a dial.
- Engage the Control: In Av or M mode, simply rotating the appropriate dial will change the aperture value displayed. If there's a specific button involved, you'll usually press and hold it while turning a dial.
- Observe the Change: As highlighted in guides like the one for Canon DSLRs, it's highly recommended to look through the viewfinder or at the live view screen while changing your aperture. This allows you to see the f-number change on the camera's display (either in the viewfinder or on the main LCD screen) and often observe the resulting changes in the exposure indicator or depth of field preview (if your camera has one).
Visual Indicators
When changing the aperture, you will see the f-number changing. Remember:
- Smaller f-numbers (e.g., f/1.8, f/2.8) mean a wider aperture (more light, shallower depth of field).
- Larger f-numbers (e.g., f/8, f/16) mean a narrower aperture (less light, deeper depth of field).
Here's a simplified look at the relationship:
| F-number Example | Aperture Opening | Amount of Light | Depth of Field | Common Use Cases |
|---|---|---|---|---|
| f/1.8 - f/4 | Wide | More | Shallow | Portraits, low light, isolating subject |
| f/5.6 - f/8 | Medium | Moderate | Moderate | General shooting, groups |
| f/11 - f/22+ | Narrow | Less | Deep | Landscapes, architecture, maximizing focus |
Why Change Aperture?
Setting the aperture is crucial because it directly impacts two key aspects of your image:
- Exposure: A wider aperture lets more light into the camera, requiring a faster shutter speed or lower ISO for a correct exposure. A narrower aperture lets less light in, requiring a slower shutter speed or higher ISO.
- Depth of Field: This refers to how much of your image is in sharp focus. A wide aperture (small f-number) creates a shallow depth of field, blurring the background (great for portraits). A narrow aperture (large f-number) creates a deep depth of field, keeping more of the scene in focus (ideal for landscapes).
By understanding and setting the aperture, you gain creative control over the look and feel of your photographs.
