New Series: Getting It Right In the Camera – Managing Depth of Field

We have a new guest author joining us. Ted Dayton (teddaytonphotography.com) has decades of experience as a commercial photographer, shooting celebrities, fashion, stock, product, architectural, and others with great success.

 He is one of the best photographers I know, producing work that is distinctive and meticulously crafted. He is also President of the Santa Clarita Photographer’s Association, and a graduate of Brooks Institute of Santa Barbara.

 In this article, Ted discusses Depth of Field, one of the key issues surrounding the topic of “Getting It Right In the Camera”.

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Popular Myths About Camera Lenses and Depth of Field

There is a myth that wide-angle lenses provide more depth of field than long lenses.

I would like to set things straight, as some readers may still be believers. We tend to use wide lenses and long lenses very differently and our perception of their relative Depth of Field properties is affected accordingly.

Wide lenses seem to have more Depth of Field because we tend to use them in ways that do in fact provide a lot of depth of field. We tend to back away from our subjects so we can see a wide view of things. This distance-to-subject dynamic affects Depth of Field as much as aperture setting does.

The lens is focused closer to infinity than for close-ups, and all lenses and all aperture settings provide greater Depth of Field as the plane of focus approaches infinity. We also tend to stop down when using short lenses in order to include as much information (sharpness) as possible in support of our wide view of things. So, we think of wide lenses as providing the greatest amount of Depth of Field.

With long lenses, we tend to shoot closer to a wide-open aperture for many reasons. Stopping down requires longer shutter speeds, which lead to shaky pictures if taken hand-held. Long lenses are harder to hold still and faster shutter speeds that are accessible when shooting closer to wide-open solve the problem.

And, long lenses are great for isolating distant subjects from other elements, especially if we use them, ahem, wide open. And so we think of long lenses as producing less Depth of Field than shorter lenses because most long lens photos we take do have shallow Depth of Field.

But it isn’t so!

Try this exercise on your own: put some common object like a basketball on the table in the backyard and take pictures of it with lenses of all focal lengths. Shoot all of these pictures at the very same aperture and fill the frame the same amount with the ball in every single frame.

Look closely when you edit and you will see the same amount of Depth of Field in every frame regardless of focal length, because of two things: the aperture setting didn’t change and the size of the ball in the frame didn’t change. This test is easier to understand if you use a fairly large aperture, like f/4. If you focus on the nearest part of the ball with a 28mm or a 200mm, the rest of the ball behind the plane of focus will be equally out of focus no matter which lens you use! (note: we did not provide an image example because we feel it is important for readers to perform this exercise and see this for themselves – David)

Summary

Depth of Field is a function of aperture setting PLUS the distance from the camera to the subject. You will soon discover that aperture setting is not the only reason why backgrounds are nice and soft or too much in focus.

The relationship of the distance from:

  • camera-to-subject
  • camera-to-background
  • subject-to-background

 ALL affect how in- or out- of focus the background appears.

 Backgrounds far away when the subject is close to the camera will be very out of focus and backgrounds close to the subject will be much more in focus.

 Said another way, the closer you get to the subject, the more you must stop down the aperture in order to see a given amount of Depth of Field. 

The farther the camera is from the subject in focus, the closer to wide-open you can shoot while still getting deep Depth of Field. As I said before, distance-to-subject has about the same effect on Depth of Field as aperture setting. How we use our lenses creates our perception that they don’t all behave the same way, but the laws of optics and 35 years of experience say that they do!

Ted Dayton, Valencia, CA

NOTE: NEW PHOTOSHOP WORKSHOPS TAUGHT BY DAVID SAFFIR – First session is Turbo Portrait Retouching, July 19, Santa Clarita, California. For more info, go here.

8 thoughts on “New Series: Getting It Right In the Camera – Managing Depth of Field

  1. Lets make another experiment, place a camera on a tripod, put a lens, say a 24mm set at f/4, focus on a subject say 15 ft away, take a shot. Remove the 24mm lens and replace with a 200mm, with everything else being equal, take another shot. Now compare the dof of the two shots. Since everything remained the same except for the lenses, I submit that the shorter focal length lens have more dof (along with more fov).

    • sounds interesting. Do you have images to show this? Please keep in mind the subject-distance criteria outlined in the post. I’m pretty sure that Ted’s go this right – but do a rigorous experiment and show us the results.

      Thanks,

      David

  2. David,

    That is the whole point, I feel that Ted’s experiment is not scientific in that it does not isolate the change to the focal length. In his experiment, changing focal lengths also required changing subject distance. To see the effect of changing one criteria, everything else needs to remain constant.

  3. You missed an important point. The subject AT THE SAME SIZE in the viewfinder. From 15′ away the subject is not going to be the same size on a 24mm vs 200mm lens.

    • Mike,

      I did not miss that, in fact it is the basis of my whole argument. Look, I’m not saying Ted doesn’t know his stuff, he clearly has the technical stuff down pat, but his experiment does not prove his hypothesis which is “There is a myth that wide-angle lenses provide more depth of field than long lenses”. If anything, his experiment proves that different focal length lenses can be set so that they all have the same dof. The reason i say this is that he is changing two variables in between readings (taking a shot), if you want to find out what is the effect of changing a one variable (focal length in our case), then everything else must remain the same. But enough about talking about it, try the experiment I outlined, and in comparing the two shots, does the shorter focal length shot have more dof? Of-course, and it also has more field-of-view, of-course again, because those are the effects of using a shorter focal length. =Þ

      call-in

  4. Pingback: Tutorial/Tips/Photographers Watch (July 8, 2009) at Imaging Insider

  5. I continue to get comments and questions on this topic – to summarize, a shorter lens will provide the same depth of field as a longer one – provided the aperture is the same, and the subject is the same size in the frame.

  6. Ted here. I know this is a 3-year-old thread, but I stumbled onto it today and read some arguments. David’s last comment above reminding everyone about two things – consistent subject size in the frame and the same aperture throughout the test – is what it’s all about. This is sort of a pointless argument because few shooters, even pros who know this to be true, really care. But optics are not what’s at the heart of this. Light bending around aperture blades is at the heart of this, making focal length irrelevant. One subject size within the frame, one aperture setting regardless of lens choice = one amount of DOF. When was the last time you used a 300 at f-16 or a 24 at 2.8? I bet you have to think about it. Yes, I know there are exceptions, but for most shooters, me included, those settings with those lenses are the exception rather than the norm. But I do have to admit that with low-noise sensors now allowing high-ISO shooting, using a telephoto hand-held and stopped-down is becoming more common.

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