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What is Depth of Field & How to Use it
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What is Depth of Field & How to Use it

If you are anything like me, understanding depth of field (DOF) was one of the biggest hurdles you had to overcome when learning the technical aspects of photography and shooting in manual mode. I would read explanations online, see links to calculators, hear it described as “shallow” or “deep” and couldn’t make sense of it all.

One day it just clicked. I’m not sure where or when, but I have a much better grasp on it now. I love using that knowledge to positively impact my own personal art as well as the art I create for my clients. My goal with this article is to explain DOF in a way that will make it “click” for you, if it hasn’t already.

Explaining depth of field starts with defining certain terms and moves to describing some things that affect depth of field.

What is depth of field?

Range of distances on either side of the focal plane that are “acceptably sharp.” (“Acceptably sharp” is where the confusion begins.) Another way to state this would be: the area behind and in front of your focus point that is in focus as well. Even though every photograph is two-dimensional, it portrays a three-dimensional world. The distance between the camera and the subject and the distance behind the subject to the “end” of the photo is the “depth” of the photo. The amount of depth that is in focus is the depth of field.

In the photo below, the whole “in focus” area is the depth of field.

What is a Focal Plane?

Distance from the camera at which the sharpest focus is attained

In the photo below, the exact location of the focal plane is obvious.

Depth of field by Cinnamon Wolfe via Click it Up a Notch

What Affects Depth of Field (DOF)?

Aperture:

In my opinion, this has by far has the greatest impact on DOF
Distance from subject: How far you are standing away from what you want to focus on. Although seemingly obvious, it is easy to underestimate the effect of distance on your DOF.

Depth of field by Cinnamon Wolfe via Click it Up a Notch

Depth of field by Cinnamon Wolfe via Click it Up a Notch

In each of the photos above, I stood increasingly farther back. You can easily see the corresponding increasing depth of focus.

All of the above photos were taken with my Sigma Art 35mm 1.4 at the following settings: f/1.4 | ISO 400 | ss 1/200

Focal length:

Some research indicates that focal length does not affect DOF, and to an extent I agree. But for practicality sake focal length does appear to have an effect on DOF so I will briefly discuss that here as well.

Sensor Size:

I believe this has the least impact on depth of field, primarily because most photographers don’t routinely switch (alternate) between crop sensor and full frame. Changes in DOF depend on whether you use a crop or full frame; but if you use only one sensor most of the time, it will not greatly affect your work.

Understanding how aperture affected my DOF was relatively easy for me to grasp. Standing in the same place, using the same lens, with my subject the same distance from me, it was easy to see how much of my image would be in focus if I switched between f/1.4 and f/5.6. However, changing my distance to subject or throwing a different focal length into the mix left my head spinning.

Examples of different depth of field

Here are some good examples of how changing your distance to subject can affect your depth of field.

In this first photo (of my handsome, always willing-to-model-for-me husband) I moved in really close and focused on his eye. As you can clearly “see” (pun definitely intended!), his eye is the only thing in focus in this image. That’s because I was shooting at f/1.4 while standing very close to him. (One of my favorite things to do!!) Since my DOF is wafer thin and his face has a lot of “depth,” only his eye is in focus. Everything else in the photo is either in front of or behind that focus point and thus blurred.

Depth of field by Cinnamon Wolfe via Click it Up a Notch

For this second image, I took two steps back and kept my camera settings essentially the same. I focused on his far eye in this image. Notice how more of the image appears in focus. However, since I had him at an angle and was shooting at such a wide aperture, my DOF is still pretty thin. Because of the angle, his front eye is not sharply focused.

Other areas, like his hair and ear and neck/shoulder line, are in focus. Those are all on the same focal plane with his eye. When looking at the photo, however, his face should be the main focus. Because of the varying depths involved and my wide aperture, the image does not appear pleasantly sharp. If he had stood directly parallel to me, both eyes might have been in focus. If I had increased my DOF by closing my aperture to f/2.5, his whole face might have been in much sharper focus.

Depth of field by Cinnamon Wolfe via Click it Up a Notch

For this final image I took a couple of steps back from my subject. You can readily see that my DOF is much greater at this distance. Almost all of his entire (studly) body is in really good shape (er…make that sharp) focus. The rest of the image blurs away beautifully to create a really pleasing separation of subject from background.

Depth of field by Cinnamon Wolfe via Click it Up a Notch

I shot all of these images with my Sigma Art 35mm 1.4 lens at these settings: f/1.4 | ISO 640 | ss 1/100

If I had taken the same shots, with the same settings, standing in the same places with a 50mm lens or an 85mm lens, the DOF would appear shallower (thinner) for each of the images.

Hopefully these examples have helped you unlock the mystery of depth of field and create more of the images you love!

Cinnamon Wolfe – Guest Post
I am a natural light photography junkie living in the middle of the high desert of California. Wife to an energetic Army husband, stepmom to an awesome teenager and pet mom to two silly pups, my days are never the same in the best way possible. When not behind a camera, I occupy my time by laughing, asking deep questions, drinking coffee and reading books. I will never turn down dark chocolate or stinky cheese.
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5 Comments
  • December 10, 2014 at 9:21 AM

    Merci,

    That was great explanation of DOF. As a beginner, this was tremendously helpful, especially with the examples.

    again, thanks!

  • December 10, 2014 at 1:00 PM

    Hi! wonderful article today. Is there any chance you could post the same pics of your “studly” husband with the 50 mm and 85 mm with the same camera settings, to see the difference? Can you tell I’m an an amateur? LOL

  • December 10, 2014 at 1:27 PM

    Hi Cinnamon Wolfe,

    Seriously nice write up on DOF!

    I know a lot of people who initially struggle with getting a grasp on aperture and depth of field especially when starting and and you have laid out it nicely in this article.

    I’m not really sure what James (the above commenter) is talking about as he really doesn’t elaborate what he takes issues with in regards to this article.

    The only thing that confuses me is the area where you talk about sensor sizes where it seems that you may be contradicting your own argument by stating:

    Sensor Size: “I believe this has the least impact on depth of field” and then you state “Changes in DOF depend on whether you use a crop or full frame;”

    It could be that I’m just reading it wrong though?

    Either way your article is still nicely written!

    • December 10, 2014 at 2:12 PM

      Hey Adam! Thanks for the comment. To clarify sensor size does affect depth of field, but since most people use one camera consistently (and thus one sensor size) I didn’t want to go into too much detail about how changing sensor size affects DOF. That subject could be a whole article on its own but since most readers of this particular blog probably don’t switch between full frame and crop, I felt it was the least important factor to discuss. Hope that makes more sense! Thanks for asking!

  • Jacqueline
    January 6, 2015 at 12:28 PM

    Sweet commentary on the hubs in between the technical info!

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