Photography FAQ Pt. 4
Do long lenses compress perspective?
There's been some discussion if not indeed argument on this with some photographers saying a long lens will compress perspective and others saying not. The thing is they're both kinda right.
If you're not sure what I mean by compress perspective please watch Focal Length Explained Pt.1 first then come back here.
I regard focal length as a creative tool to aid composition and change the look and feel of the image. Focal length and composition are best mates and help each other out all the time - as good friends should.
I prefer to teach in a "Do this and it'll look like that" kinda way however physics are a part of all photography and I know some of you will want to know why a thing does what it does.
It's not the actual focal length which compresses perspective - it's the distance between the camera and subject which gives this effect. There are however downsides to ignoring the long focal length aspect of compressing perspective because you'll reduce image quality and throw away a lot of very expensive mega pixels in the process.
Do Long lenses Compress Perspective? is a basic explanation but if you'd like to know more about how it works here's some links to some excellent articles on the subject.
- The Focal Length and Perspective Myth - by PixelPix
- Understanding Perspective and Focal Length - by PhotoNaturalist
- Myths About Lens Compression - by Scott Bideau
So what is actually happening is this. As you extend the focal length of the lens you have to move further away from your subject to maintain the composition you want and compensate for increased magnification. As your subject to camera distance increases the compression of perspective effect becomes more pronounced.
As to the physics graphs and angles - I leave that to the guys linked to above. Knowing I can create my images looking the way I want to by increasing / decreasing my focal length is enough for me...