There’s a common belief that wide-angle lenses cause perspective distortion. That’s where the subject closest to the camera is relatively larger than the subject further from the camera. We’ve all seen the close-up photos of dogs with giant noses taken with wide-angle lenses.
It’s really not the lens at all, though. It’s simply the distance from the camera to the subject. It just happens that when you put on a wide-angle lens fill the frame with the subject, you’re close to the subject. When you fill the frame with a telephoto lens, you’re further from the subject so the perspective effect is less strong.
I set up a little demonstration to get a better sense of what it means for my lenses. I filled the frame with each of the following photos. As each photo used a different focal length lens, the distance to the camera was different for each.
35mm lens. The near corner seems much larger than the far corner and the top sticks forward like an overhang. This makes the image appear front-heavy. The left and right sides also splay out instead of being straight up and down.
50mm lens. This lens is supposed to be similar to the way we see the world. It still seems front-heavy to me, with the near corner appearing larger than I would expect. And the sides do splay out still, but not as much.
100mm lens. This looks like a nice balance between the front and rear corners. The front is a little bulkier, which gives you a clue to it’s three dimensions. And the sides splay out slightly.
135mm lens. This image looks very uniform to me. The front and back corners have about the same bulk. Because of that, it’s mostly the lighting that gives the clue that the box is three dimensional. The sides are about straight up and down. The box seems narrower than in the 35mm lens photo. The greater distance has a slimming effect. Another reason why medium telephotos are used for standard portraits.
The other difference is that the wider the lens, the more of the background you see. This is why the 35mm lens is the classic lens for environmental portraits and travel photos. For this type of photography, the subject needs to be placed in the context of the surroundings. For a portrait where you want to isolate the subject, you usually use a medium telephoto, such as the 100mm or 135mm lens. It cuts out distracting background to the left and right of the subject.
I was expecting that the 135mm lens would give the most natural-looking result because the distance creates the least perspective distortion. But I think there’s too little distortion so you you don’t get all the clues that help make an image look 3D.
You can straighten lines in Photoshop and Lightroom. Here’s what happened when I used Lightroom to make the left and right edges Perpendicular.
Not so great. You’ve really got to get it right in camera.