Distortion based on Focal Length or FOV??

Started Mar 23, 2014 | Discussions thread
David Wyman
David Wyman Contributing Member • Posts: 509
Re: Distortion based on Focal Length or FOV??

This is a complicated subject. And Craig and Ray gave great answers.

I'll add that focal length isn't the same field of view. Focal length refers to the distance it takes to focus an image which, put somewhat simplistically, is the distance from the lens in your lens barrel to the sensor in your camera.

So a FF 24mm lens on a FF camera doesn't offer a 24mm field of view. That's the distance it takes to focus an image. An 24mm lens offers about a 74 degree horizontal field of view, a 53 degree vertical field of view, and an 83 degree diagonal field of view.

With a 17mm lens on a 4/3 sensor, the FOV will be 56, 35, and 65 degrees.

Forget those numbers, though. Because in real world use, it won't matter which lens you use on which camera. You're going to have to stand back a bit to take in a group of people. And once you stand back a bit (enough to get your group in your photo), no matter what the lens or which camera format you use, you're not going to have an issue with distortion.

For a portrait of one person, yes, you can distort a face if you stand too close. You can, though, use a 24mm lens (on a FF camera), or even a 10mm lens on an A6000 (when you get one), and simply stand back, from where you would with a "normal" lens, and crop the image; there won't be distortion. You won't have as sharp an image, because you'll be farther away from your subject than you would be with a normal lens, and in the process you'll lose some detail.

And why/how do you get distortion with a wide angle lens? Because as a rule, you can come closer with a wide angle lens than you can with a normal or telephoto lens. Try it in a mirror: stand back and check out the size of your nose and ears. Move as close as you can to the mirror and see what happens.

So if you have a 24mm lens on a Nikon D800, or an 20mm lens on an Sony A6000, or a 4.7mm lens on a Panasonic LX7, relax and be happy, because you're going to be able to get a group photo without much distortion.

 David Wyman's gear list:David Wyman's gear list
Panasonic LX100 Sony Cyber-shot DSC-HX90V Sony RX100 VI Nikon D600 Sony a6000
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