Eric Stoner
Eric Stoner

Eric's professional photographic career spans over 25 years specializing in portraits, weddings and commercial photography using everything from simple lighting to very complex.

Lens Compression & Perspective: How they affect portraits

June 03, 2014

As a portrait photographer, I’m a big fan of larger focal length lenses for many reasons. Some of them include the ability to isolate my subject from extraneous clutter, shoot with shallow depth of field and compress the background. What do I mean by “compress”? Take a look at the following images, one taken at 50mm at f/5.6 and the other at 180mm also at f/5.6. You’ll notice that the background in the first image is a bit more distracting, wouldn’t you agree? Also, take a look at the second photo and you’ll notice it’s more difficult to tell how far away the brick wall is from the subject. This is an effect of compression, making the background appear larger and cleaner especially at wider apertures. The larger the focal length of the lens you’re using, the more compression you’ll notice in the image.

Shot at 50mm and f/5.6
Photo by Eric Stoner

 

Shot at 180mm and f/5.6
Photo by Eric Stoner

 

Many get confused between lens compression and depth of field. They are different phenomenon. The simple answer is that depth of field is a zone (deep or shallow) of sharpness around an object you focused on. Compression (using telephoto lenses) forces the background to appear closer or further away (using wide angle lenses) from your subject. Take another look at the images above and you’ll notice that in the shot taken at 180mm, it is more difficult to figure out the distance from the subject to the background. Why is this important? For me, I can photograph a subject effectively by cutting out distracting objects in the background AND by using a wider aperture in combination with a telephoto lens, I can shoot at just about the worst possible location you can imagine and make it look great! Telephoto lenses have a narrower field of view, but they also allow for more distance between you and your subject as seen in the diagram below.

Looking at the two images below, notice the subject composition is relatively the same (from the waist up) however, do you notice anything that’s different? You see more of the background, don’t you? AND the details in the background are more defined, aren’t they? There is a perspective issue at play here. Even though they were both taken at an aperture of f/5.6, the first image was shot using a 24mm lens and the second at 85mm. In order to fit the model in the same relative composition, I had to move closer to her while using the 24mm (refer to diagram above). I’m not saying one is right or wrong, just different, and depending on your taste, you may gravitate toward one or the other.

Shot at 24mm and f/5.6
Photo by Eric Stoner

 

Shot at 85mm and f/5.6
Photo by Eric Stoner

 

One note on lenses . . . no matter what conventional lens you use, the closer you get to your subject, the more out of focus the background will appear, even using small lens apertures like f/11 or f/16. Try it!

A good exercise for getting familiar with these concepts is to put them into practice. Photograph a subject at varying distances, as well as different focal lengths, and run through the entire aperture range at each distance. Make prints to see your results and you’ll know which lens to use, based on your testing, BEFORE you start!

For me, telephoto lenses are tools I can’t live without because of the concepts I’ve described in this article. I’ve been known to give my subjects two-way radios for communication because they were too far away from me to direct from my camera position while using a 500mm lens to photograph them!

Until next time, stay focused!

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