Digital SLRs - Depth of Field Preview Button

The depth of field button allows you to see the amount of a scene that is in or out of focus before you take a photo. Not all Digital SLR have a depth of field button, yet it can be a tremendously useful feature to have. In many cases, without this feature, you are guessing what your photograph is going to look like. When you press the shutter button and the scene is captured you may well end up with a picture that looks very different to the one you were expecting.

In some ways a depth of field button is a bit of a "catch 22 situation". As you get more experienced as a photographer you develop your eye so you will have a much better understanding of how your photographs are likely to look.

This extra experience will help you to visualise how your photographs will turn out. Once you reach that stage you will become less reliant on a depth of field button. Ironically by this time you may well have moved up to a more advanced Digital SLR. At that level your camera is far more likely to have a depth of field button.

digital slrs

What is Depth of Field

Depth of field is the area of a photo that is in sharp focus. You are likely to have seen landscape photos where all of the shot is in sharp focus. This is known as having a deep depth of field. By way of contrast you will have seen shots where just the main subject is in focus. To highlight the subject the rest of the photo is thrown out of focus. This type of photo is said to have a shallow depth of field.

Changing Depth of Field

One way to change the depth of field is to adjust the size of the lens aperture. If you are using a Digital SLR without a Depth of Field Preview Button you will not be able to see the impact changing the size of the aperture has on the overall sharpness of your shot. Therefore you will be none the wiser how much of your shot is in sharp focus when you view the scene you are about to photograph either on the LCD screen or through the viewfinder.

The reason for this is that the image of the scene you view through your camera has a been created using a wide open aperture to ensure what you see is as bright and clear as possible.

When you use the depth of field button your Digital SLR changes the image you see on the LCD screen or through the viewfinder to use the aperture you have selected for the shot. This then gives you an accurate representation of how your photograph will look when it has been taken.

Digital SLR Guide Pages

Digital SLR Basics
Digital SLRs and Digital Cameras Key Differences
Digital SLR or Compact System Cameras
Digital SLR Handling
Help for Beginners

Lenses and Accessories
Buying a Camera Lens
Memory Cards
Digital SLR Accessories

Learn More About Features
Resolution and Sensor Size
Sensor Cleaning
Manual Exposure Modes
ISO Range
White Balance
Auto Focus
Drive Modes
Scene Modes
Help With Tricky Lighting
Metering Modes
RAW Mode
Live View and Articulated Screens
Flash Options
Movie Modes
Depth of Field Preview Button
Image Stabilisation
Mirror Lockup

Current and Recommended Models
Summary of Current Models
Recommended Digital SLRs

Digital SLR Guide Author
This guide was written by Ian Younger

When to Use a Depth of Field Button?

The depth of field button is of greater importance if you are planning to take photographs with the background thrown out of focus. Without having the button available it is very difficult to predict exactly how much of the scene will be in focus and how much of the scene will be out of focus. This is especially true if you are taking a shot where you want to be very accurate when it comes to what is in and out of focus.

If you mainly take photos where the entire scene is in sharp focus the depth of field button is of less importance. This is because once you have worked out the lens aperture settings to create your desired effect you can carry on happily with those settings.

Depth of Field Examples

Depth of Field Deep

Depth of Field Deep

Depth of Field Shallow

Depth of Field Shallow