Friday Five: Depth of Field
This week we’ll be talking about depth of field (DOF) and taking a look at 5 (or so) images that’ll help us understand this vital aspect of photography. Don’t forget, these photos and more are available to you in all their high resolution glory in the OU Image Library. Just shoot Morgan (firstname.lastname@example.org) an email about which photo you want along with its intended use and she will likely be able to send you the high-res version.
First, what is “depth of field”?
Depth of field is the term used to describe the range of distance that is acceptably sharp in an image. Basically, it’s that part of the photo that looks clear and in focus. Let’s take a look at our first image to get a better idea.
No.1 South Oval Fountain
When it comes to taking pictures, photographers have an infinite number of variables to consider. Whether it’s choosing between a high or low shutter speed, setting the sensor sensitivity, or choosing the best lens for a job, the possibilities are endless. One of the biggest factors though is figuring out where your focus is going to be. For instance, the picture above has a very obvious focus point, right? When you look at the picture, you should naturally be inclined to look at the fountain. Why is that? Because, relative to everything else in the picture, the fountain is most focused. Or, in photo-jargon, it’s “sharp.” This sharpness is a result of two things: One, I placed the fountain in the center of the camera’s depth of field, and two, I made that depth of field very shallow by changing the aperture. Now, we won’t get into all the technical details regarding aperture but just know that “aperture” changes how shallow or wide that field of focus is. If you’re interested in learning more, check out this neat camera simulation site that Canon put together.
Confused? Don’t worry. It’s a bit tricky. Let me show you a real life example of what I’m talking about. Below are two identical pictures with the only difference being the change in aperture, or the depth of field.
The image on the left has a very shallow DOF. I made sure to focus on the pig-suit guy and I set the aperture to a low number, which means that DOF got very narrow. The only thing in focus was the first Lego man. In the second image you’ll notice that both Lego characters are in focus. This is because the DOF is much wider which included both characters in that acceptably sharp distance.
No. 2 The Day Lilly’s of Carpenter Hall
One of the best reasons for using shallow DOF is to highlight small details. The picture above could have been just as easily shot with a wide DOF. If I had done that, Carpenter Hall would be less blurry and the entire picture would have been filled with a more detail of both the flowers in the foreground and the building in the back. However, more detail isn’t always what is best. Because the background is blurry, it’s much easier to look at the details on the flowers.
Now, let’s talk for a moment about the cons of using a shallow DOF. While this photo isn’t terrible, it does suffer from a slight bit of blow out. Looking at the petals, you’ll notice the sunlight is causing a bit of overexposure, or blowout. Basically, in that tiny area of the image, there is just too much light coming in, and as a result, the yellow petals look white in a few places. Now, this isn’t big deal, but it’s something that you might run into when shooting at wide depths of field.
No. 3 #ShareACoke with Boomer & Sooner
A lot of the time, I need my background to be out of focus while still maintaining a distinct sharpness to the main subject. Again, how I choose to set the exposure and take an image will depend on a lot of variables. How far away am I from the subject? How big is the subject? How much distinction do I want there to be between the subject and the background? In the picture above, the priority was getting those coke bottles as sharp as possible (they need to be readable). However, too narrow of a DOF would have made the mascots too blurry. But, had I shot it at a super wide DOF (like at F/11-22), I would have made the trees in the background just as clear as the bottles. All these things are factors in how you want your image to turn out. I ended up blurring out the background as much as I could before the OU sign in the background was unrecognizable.
No. 4 Bizzell Memorial Library
We’ve talked mainly about shallow DOF. It’s most commonly used when taking pictures where you need to isolate your subject from the surroundings. But what about when you don’t need to do that? For example, landscape photography, or really any photography where you’re trying to capture a scene, story or large structure. For things like that, you’ll want to use a much wider DOF (like F/7-22) that will allow you to capture a much broader picture. One that details the whole scene, not just a particular subject. In fact, some photographers even call those higher aperture numbers the “storytelling apertures.” The picture above was taken with an aperture of 7.1, which allowed for everything you see in the picture to be caught within sharp focus.
No. 5 Carnegie Building Flora
The last picture was taken in one of my favorite locations on campus. Covering the entire north side of Carnegie Building you’ll find thousands of vines that seem to defy gravity. I’ve taken many photos of this wall, and while the one I’ve featured above isn’t my favorite, it’s a great representation of how DOF can impact the composition of your image.
Next time you’re out shooting, try to use your focus in new and interesting ways. Mess around with that aperture. Take every photo with both a wide and shallow DOF. Who knows, maybe you’ll end up with a jaw-dropping image like THIS.
See ya next Friday,