Lens compression (Perspective Distortion)

Lens compression is a peculiar effect that occurs when you change the focal length of the lens.

There are two effects of changing your focal length (either by zooming in and out with your telephoto, and/or changing to a different lens size on your SLR camera).

The first effect is the potential distortion of your subject at a small focal length, such as at 16mm, or a flattering perspective at a larger focal length (such as at 200mm).

The second effect is the relative size of background objects in relation to your subject.

Let’s take a look at these two effects in an example.

When you look at these images, if you haven’t seen this effect before, it can be quite astonishing. There’s no trickery here – we didn’t move the trees or the model or the vehicles in the background. This is all done by changing the focal length of the lens and repositioning the camera either further or closer to the subject (the model).

Focal length of 86mm

In the first image, note how flattering the capture of the model is. There is no distortion of the appearance of her body.

Also note how close the black truck and the background tree appear to be in relation to the foreground tree and model.

Focal Length of 70mm

Focal Length of 70mm

Note in this next image, we reduce the focal length to 70mm, and the black truck seems to get farther away.

The perspective on the model is still pleasing, with an unnoticeable perspective change.


Focal length 48mm

The next two images you will see the black truck seem to get farther away, and subtly, the perspective on the model becomes less flattering.

Focal length 24mm

Focal length 11mm

In this image, the black truck and farthest tree are almost too small to see.

The model’s appearance is distorted, and could be interpreted as unflattering (or creative). Had we taken a higher or lower position for the camera, it would have been even more distorted (making her legs or head look bigger, depending on the camera height).

So as you can see, the focal length of your lens not only controls how far away you can shoot (how much you can zoom), but can also impact the appearance of the perspective of the image. This could be used for creative benefit, but can also be used at the subject / client’s expense.

Use this information wisely!

4 comments on “Lens compression (Perspective Distortion)
  1. Paddy says:

    Nice post 🙂

    If I were to take a photo with a 50mm lens, and then one from the same distance with a 28mm lens, and then cropped the 28mm so that it had the same field of view as the 50mm, would they both have the same perspective compression? Would the 50mm one still look more compressed?

  2. admin says:

    That’s a great question. I believe it would have the same compression, but obviously you would lose detail through cropping (you would have less pixels of information when you crop down). But I will have to test this theory out and follow up with an update post!

  3. Paddy says:

    Had some free time today so I answered the question: seems that other than differences in lens distortion (barrelling, pincushioning) you get pretty much the same image

    http://www.flickr.com/photos/pskillen/5320417908/
    http://www.flickr.com/photos/pskillen/5320418272/

  4. admin says:

    Excellent! Thanks for the update and the research time you put in.