Photography and Art

Thursday, November 10, 2011

Telephoto Lens Compression

One of the results of shooting through a telephoto lens that always surprises photographers is the compression effect. Here's an illustration using three photos from a recent shoot. I didn't set out to shoot a comparison of three focal lengths, but it just worked out that way.

Here's a photo taken with a focal length of 100mm. The other side of the lake looks roughly like it does to the naked eye.

Here's the same subject taken with a focal length of 200mm. Not only is the subject cropped as you would expect, but the far shore now is starting to look closer than it does to the naked eye. The distance from the sailboat to the far shore is being compressed.

While this is not the same photo as above, the distance to the far shore is exactly the same and the sand bar in the foreground is the same one as in the first two images. This image was taken with the lens set to 300mm. Note how the lake now starts to look like a river. The compression effect is quite severe and if you were familiar with this view, the compression would strike you as strange and bothersome.

Compression is something to think about when you are composing a scene. It can often be used to your advantage. In the photo below, I deliberately used a wide angle lens (24mm) to make the building in the foreground stand out from the background. Most people who shoot this scene use a medium telephoto lens so that the skyscrapers in the background loom over the smaller flatiron building.

Here's an example of the same scene shot with a longer lens (70mm). The intent of this image was to focus on the reflections in the road and compress the background so that the flatiron building and skyscrapers loom in the distance.

It's pretty amazing how the skyscrapers seem to move and get larger from one image to the other.

The moral of the story is: choose your focal length with care. Bear in mind that longer focal lengths produce a compression effect that may be unwanted. Shorter lenses also spread out the subjects in your photo and can also have unwanted consequences. The naked eye is roughly equivalent to a 50mm focal length, so both shorter and longer lenses have the potential to be disturbing. Often, this can be a good thing, but not if the effect is unintended and distracting.

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