Lens Compression & Depth of Field

By | 2016-12-18T17:01:12+00:00 April 20th, 2011|7 Comments

One thing that I do frequently with my photographs is I use a combination of a wide aperture and a long focal length to decrease the depth of field (DOF) in my images to add more compression to the background, making it soft and out of focus. When photographing this cake pop I thought I would create some photos that show how different aperture settings can affect the background of an image.

The photos above show the final photograph along with a behind-the-scenes image. (For the final image I actually merged two files together … one at ƒ/4 to get a soft background, and another at ƒ/11 to get sharper focusing on the cake, since I wasn’t happy with the focus quality on the cake at ƒ/4). For this setup I used window light, bounced onto the subject with white foam board. For the background I used Christmas-tree lights in front of a soft yellow-ish cloth-covered piece of foam board to add more gold tones to the background, and bounced some light on it to make it a little brighter (that’s the foam board you see attached to the boom stand). The cake pop was about three feet from the background lights, and the camera was on a tripod (that funny-shaped black thing in the image on the right) approximately four feet from the cake pop. The DISTANCE you put between the subject and the background, and the FOCAL LENGTH you use (longer is better) are important if you want to achieve a very soft, out of focus background like I did here in this image.

The photos below show the same setup with different apertures, starting at ƒ/4 and going all the way to ƒ/32. All images were photographed at 200mm on a Canon 7D with no change to anything except the exposure settings. (To see it “in action” I created an animated GIF so you can watch the changes happen quickly.)

BTW, here’s a link to the recipe I used to make this cute little guy. :)

About the Author:

My name is Nicole and I'm a photographer, author, & educator living in Lincoln, Nebraska, USA. When I'm not making photos I'm writing books and tutorials for my online store, Learn more about me and my story here.

7 Comments

  1. Corinna April 20, 2011 at 11:45 am - Reply

    Great comparison and explanation!

  2. tolga April 20, 2011 at 10:01 pm - Reply

    well done Nicole,
    the final image looks stunning.

    you are going to make me buy a 70-200 with these shots :-)

  3. Thanks for including these comparison shots. I wish I would have found your blog when I bought my first DSLR. I love your easy explanations.

  4. Michael Huber AIA LEED AP April 28, 2011 at 1:19 pm - Reply

    Love the simple explanations and examples. Thanks for sharing! I also like hearing you on various podcasts. Enjoy your move to the northwest and a new adventure!

  5. Michael July 29, 2011 at 12:58 am - Reply

    You demonstrated differences in depth of field but didn’t address lens compression at all.

    Longer focal lengths, especially when used with a shallow dof, ‘compress’ the foreground and the background and making objects appear closer together than they actually are.

    An example of lens compression can be found here: http://www.photocrati.com/the-curious-case-of-lens-compression/

    • Nicole July 29, 2011 at 10:23 am - Reply

      I did mention how I achieved lens compression with this image in the post, I just didn’t show any examples.

  6. Oisin Connolly October 7, 2012 at 7:36 am - Reply

    Great tutorial and explanation. I’ve always wanted to know how people get such crisp subjects and yet have a lovely soft focus on the background. I guess it must mainly be post production then?

    Also i’ve always wondered, when you use a longer focal length, does the depth of focus fall off at the same rate as using a shorter one?

    With my 50mm at f1.8 I often find that too little of my subject is in focus for my liking. Would I be better off using a telephoto lens?

    Thanks,
    Oisin

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