A Guide to Perspective Distortion

What it Looks Like

All the photos that I will show here were taken in APS-C size format.

In the next 3 photos the physical size of the arches is the same from front to back.

This photo was taken with a 31mm lens and is what I am going to call my normal lens length. It was taken from about 10-12 feet from the front arch and is about what prospective distortion you would perceive with your own eyes with you standing here.  What you should be looking at is the inside size of the arch in front to the inside size of at the back. As you would expect, the front is bigger and gets smaller as you go back.

This is a 135mm lens from about 30-40 feet back. To get the framing right it should have been a little farther back but I was stopped by some trees. Even though it is not the perfect distance (it would only show the effect more) it is close enough so that you can see the differences. As you can see the arch in front is about the same size as the arch in front in the first photo but the arch in back is much bigger then the arch in back in the first photo. This is an example of far perspective distortion. Far is only relevant to what you are comparing it too, in this case 31mm (the normal) at 10-12 feet.

This is using an 8mm about 3-4 feet from the front arch. As you can see the arch way in the back looks very small now. This is an example of near perspective distortion as referenced to a 31mm (normal) at about 10-12 feet.

Now I need to stress it is not in the lens it is in the distance, which is why I am giving the distance with every photo. If I only gave the distance and not the lens length (assuming you understand perspective distortion) you would totally understand what is happening. In theory I could have taken the photo at 30-40 feet with the 8mm lens and cropped it down to get the same framing and you would see the same thing as the photo using the 135mm lens. The problem with doing that is the camera/lens doesn’t have the resolution to do that. The lens is for framing so decide what perspective distortion you want and pick your point of view then pick your lens to give you your framing (angle of view).