What is Depth of Field??? Depth of field (DOF) is a creative tool that can be used to emphasize or deemphasize a subject. I’ve written a good bit about learning to choose settings to get a good exposure, but today, I’d like to write a bit about choosing settings to get the artistic look that you are going for. Exposure, check. Let’s talk about art. So, what is depth of field, and what all can I do to affect it?
What is Depth of Field (DOF)?
When you use a single focal point to focus your camera, there will be an area that stretches before and after that point that will also appear in focus. This range of area is called the depth of field. Depth of field, simply put, is the amount of the image that is in focus. The focal plane is another term for the slice of the image that is in focus. It can be measured, and is precisely the distance between the first point of focus and the last point that is in focus. A shallow depth of field has very little in focus. A deep depth of field (like what is used in landscapes) can have the entire image in focus. The image below is an example of shallow DOF.
What Affects Depth of Field (DOF)?
A few of factors come into play when speaking of DOF. It can never be just simple, right? The distance from the photographer to the subject affects the DOF. The focal length of the lens affects DOF, and as I talked about in Shooting in Manual Mode : Aperture, aperture affects the DOF. Oh, and one more thing, the sensor size on your camera affects DOF.
I love a shallow depth of field, so it makes me happy that there are so many ways that I can control it! Photography becomes art when you take over control and really own your settings, the composition, the light….everything that contributes to making your photo.
Distance to the Subject
The closer the photographer is to the subject, the more shallow the DOF will be at a given aperture. And vice versa. If you are standing farther away, the DOF will be deeper. This means the background will be blurrier if you are closer to your subject than if you take a few steps back and zoom in to the same crop. In these images, I used my Nikon 35mm 1.4 lens and just took a step back for each of the three images. If I had taken 10 steps back, the difference in depth of field would be much more drastic.
Same aperture, a wide lens vs. a telephoto lens, the telephoto will have a more shallow depth of field. And vice versa, if you are using a wider lens (zoomed out to show more of the environment), your DOF will be deeper. So, in these images, I stood in the same place, used the same ap and just changed out the focal length with my lenses. Notice the difference between the DOF of the 35mm versus the 200mm. Also take note of the background. That’s bokeh, y’all. <3
Yep, you heard it here first. Size matters. Ha! When it comes to the sensor anyway. Just kidding!!! The size of the sensor does affect the depth of field though. With a larger sensor, more information can be packed into each image, and more of the actual scene is captured. When you hear the terms “Full Frame” and “Crop Sensor” both are referring to the size of the sensor in the camera. Where a full frame will capture the entire 35mm scene, a crop sensor essentially crops the image in the center and you get what will look like a someone took an image with a 50mm lens. So, to take the same image with a full frame camera as with a crop sensor camera, the person with the full frame will need to step in a few steps closer to the subject, which shortens the distance to the subject which decreases the DOF. This is the number one reason that I shoot with a full frame camera. I LOVE a shallow DOF.
Sorry I don’t have an example! I have a crop sensor Fuji XT-2 but I don’t have an equivalent lens to use on my full frame Nikon D750. The difference in DOF is due to the DISTANCE between framing say a 35mm lens image and then one using a 50mm. So, look above at the difference in the “distance to subject” paragraph, and that will be about the difference between a FF and a crop when it comes to DOF. 🙂
I hope I have answered your question “What is Depth of Field”! Check out this post about shooting in manual mode to learn more about taking control of your camera!