Why Size Matters - Lens Compression at 400mm

Most the time when I am out doing landscape photography, I have a Canon EF 16-35mm f/4L IS and Canon EF 70-200mm f/4L IS with me. On roadtrips, I try to bring my Canon EF 100-400mm f/4.5-5.6L IS II - it’s a fantastic lens with great image stabilization and impressive image quality. Unfortunately, it is a bit too big and heavy for me to bring out more often!

On a recent trip through the Canadian Rockies, I had this special lens with me. I knew of this tree in Banff National Park and knew I wanted to photograph it. While originally a typical portrait (vertical orientation) photograph, I later switched into landscape orientation and took a vertical panorama (8 individual images), yielding me a larger perspective and much higher resolution.

Now, this tree could have been photographed with my 16-35, or even my 70-200 - but to be able to shoot it at 400mm with my 100-400 lens yields far different and unique results. Thankfully, this specific area afforded me the ability to step back further from the tree, but by zooming in I was emphasizing the lens compression you get when you shoot at longer focal lengths.

What Is Lens Compression?

Lens compression (although it has more to do with a given focal length and nothing to do with the lens itself) works because we’re able to get further away from our subject, but still zoom in as if we were much closer. As a result, it creates the appearance that the background has been pulled in closer, distorting it to be larger than it is. This in turns has a bit of a flattening effect on the scene, making subjects throughout the depth of the scene appear far closer to each other than in actuality. The inverse happens with wide angle lenses, as we will stand closer to our subject it appears larger proportionally to the background.

The (almost) same scene shot at multiple focal lengths from 20mm to 400mm

The (almost) same scene shot at multiple focal lengths from 20mm to 400mm

In the example above, at both 20mm and 35mm, we can clearly see the space around the tree - we can see lots of foreground and background trees, and the trees along the side of the road also appear further away from our tree in the middle. At 20mm, we cannot get close enough (without tilting the camera too far upwards and distorting the photograph in a different way), and as a result it looks small in the scene.

As we get out to 70mm and beyond, we start to see the lens compression phenomenon kick in. As we step back and increase our focal length, the scene gets flatter and flatter where once we reach 400mm we’ve included far more trees along the road, the trees behind our main subject appear to sit almost right behind it, and we lose the ability to sense that in fact there is about 100m (300 feet) of tree-lined road in front of the main tree (or more!).

Lens compression is often talked about in portrait photography for the same principles. Longer focal lengths give us the ability to increase distance from our subject which gives us the effect of creating a more flat, less distorted face.

Photographing the Tree

I shot this video when I was photographing the tree, so you can see first-hand the area and get a better idea of the area I was photographing in as well as just how far away I was from my subject when shooting at 400mm.

Your Turn

If you haven’t already, take a chance to go out and give the technique a try! I’d love to see some examples of how you have utilized compression in your photos!