Week 6 – Depth of Field.

Tweet This week we tackle depth of field, which describes how much of your photo appears to be in focus, from the front of the image to the distant background.The above photo of a girl boogie boarding has a relatively narrow depth of field, with the girl and her board appearing sharp, and most of […]

A girl boogie boarding at Popham Beach State Park in Phippsburg, Maine.

This week we tackle depth of field, which describes how much of your photo appears to be in focus, from the front of the image to the distant background.The above photo of a girl boogie boarding has a relatively narrow depth of field, with the girl and her board appearing sharp, and most of the water in front of and behind her being out of focus. The below photo has a lot of depth of field and is basically sharp from the snowshoes in the foreground, only a couple of feet away, to the field and bluffs in the background (infinity).

Snowshoes on a bluff overlooking the Merrimack River in Canterbury, New Hampshire.

Now how is it possible that the same camera can create images with such different depth of field? In the video, I explain how depth of field is determined by three factors: focal length, camera to subject distance, and aperture. Wider focal lengths give you more depth of field than longer focal lengths, while the closer you are to your subject, the less depth of field you’ll be able to achieve. That’s why macro photos and photos shot with those big wildlife lenses (like 500mm) tend to have very shallow depths of field. When it comes to aperture, the bigger your aperture, the less depth of field you get. So F16 has more depth of field than F4.

A smaller aperture (larger F-number) creates more depth of field than a larger aperture.

As you can see in the above photo, shot at two different apertures, different depths of field can have a significant impact on how your photo looks, so please get in the habit of choosing your own F-stop by shooting in aperture priority or manual exposure mode. Don’t shoot in program mode and let the camera make this decision for you – it’s too important! Sometimes you want a narrow depth of field – portraits, and flower close-ups are perfect examples – and you can usually achieve this by getting closer to your subject, using a longer focal length and/or using a large aperture (I like F2.8 or F4.) Sometimes you want a very large depth of field, like in the classic Ansel Adams-style big landscape shot. For these shots you can go the quick and dirty route by setting your aperture to F16 or F22, focusing about a third of the way into the scene and shooting. To be more precise, you need to calculate the hyperfocal distance for the shot. This is the distance from the camera that you can focus at to achieve maximum depth of field, from a point half way between the camera and the hyperfocal distance to infinity. This handy distance to know used to be printed right on the lens barrel of many lenses, but no more. Today, you need to calculate it yourself. You can find depth of field calculators online – here’s a good one: http://www.dofmaster.com/dofjs.html – or if you want to have one with you in the field you can use the iPhone app, PhotoCalc (in the video, I said there is an Android version, but alas I was wrong – I’m sure you can find something similar out there in app world.) Below is a chart I created using a depth of field calculator for select wide angle focal lengths.

Depth of Field Chart for Wide Angle Lenses

Focal Length

F8

F11

F16

F22

12mm

1, 2, ∞

0.7, 1.4, ∞

0.5, 1, ∞

0.35, 0.7, ∞

14mm

1.35, 2.7, ∞

.95, 1.9, ∞

.65, 1.3, ∞

.5, 1.0, ∞

17mm

2, 4, ∞

1.45, 2.9, ∞

1, 2, ∞

.7, 1.4 ∞

20mm

2.75, 5.5, ∞

2, 4, ∞

1.35, 2.7, ∞

1, 2, ∞

24mm

3.95, 7.9, ∞

2.85, 5.7, ∞

1.95, 3.9, ∞

1.45, 2.9, ∞

28mm

5.35, 10.7, ∞

3.9, 7.8, ∞

2.7, 5.4, ∞

1.95, 3.9, ∞

35mm

8.35, 16.7, ∞

6.1, 12.2, ∞

4.2, 8.4, ∞

3.05, 6.1, ∞

Measurements are in feet.  By focusing at the middle number (the hyperfocal distance,) the image will be sharp from the first number to infinity.

This chart is only accurate for a camera with a full frame sensor. If your camera uses a smaller sensor size, you will actually get more depth of field than what is shown here.

 Here’s your assignment for the week:

1) Watch the video to learn more about depth of field.

2) Get out and shoot. Shoot the same scene at different f-stops to see the difference in depth of field. Make some photos where you maximize depth of field by using hyperfocal distance, and make some photos where you minimize depth of field by using a large aperture and/or a long lens. Try to get a feel for how to use depth of field with your photographic style.

3) Post one or more photos to our on-line Flickr Group before Wednesday, March 28th. At least one photo with a shallow depth of field and one with a large depth of field would be great (they don’t have to be of the same subject.)

On Thursday, March 29th, I’ll select one photo to critique and mail a copy of The AMC Guide to Outdoor Digital Photography to the photographer.

On a side note,  the early-bird deadline for my May 26-28 Acadia Workshop is March 26th. Sign up before then to save $50.00.

Thanks for watching, and have fun!

-Jerry

4 Responses to “Week 6 – Depth of Field.”

  1. David Pinkhnam says:

    I love the opening and closing music. However, now I can’t get the tune out of my head. I may not complete this weeks assignment. I’m dealing with bronchitis – and I’m not the best of patients – and I’m going to DC tomorrow for the Photoshop convention. First time!

  2. Ratul says:

    I always keep getting confused about hyperfocal distance. My question is if I shoot at f/16, where should I focus (at about 4- 5 feet) away if there is no foreground object or if I use distance scale on the lens, again what should I focus on ? Thanks.

  3. Ratul – it depends on the focal length of your lens. If you want to maximize depth of field from infinity to a point close to the camera, you need to focus at the hyperfocal distance. For example, if you look at the chart above and you’re shooting at F16 with a 24mm lens, that distance is 3.9 feet. By focusing there you will get from 1.95 feet to infinity in relatively sharp focus.

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