Does zooming in differ from cropping later, especially for portrait distortion?
Asked 4/4/2017
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If I photograph a subject from the same camera position, is using a longer focal length equivalent to using a shorter focal length and cropping the image to match the same framing? Aside from losing resolution when cropping, does anything else change—especially distortion or perspective in portraits? How is this different from using a longer focal length and also backing up?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
6
From an idealized perspective, cropping and enlarging is functionally identical to zooming. In reality, of course, you lose pixels, and you probably lose real resolution as well since you are demanding more from the lens and camera system by looking more closely. Since you are discarding the edges of the frame, optical flaws — including lens distortions will be changed, often for the better.
But, you specifically ask:
I am asking if there is a difference, distortion-wise, like when increasing focal length and backing up.
which indicates that you are talking about perspective distortion. Perspective is affected by exactly and only one thing: where you stand. See What is the difference between perspective distortion and barrel or pincushion distortion? for more, or one of What does it really mean that telephoto lenses "flatten" scenes? or What's the succinct reason for face-warping in wide angle lenses?.
So: standing in the same place and cropping from a wide lens or zooming to the same framing will give exactly the same perspective. And, backing up and cropping or zooming to match will give the same perspective — but a new one from your earlier position. If you stand in the same place, there is no way to change perspective by either zooming or cropping.
Originally by user1943. Source · Licensed CC BY-SA 4.0
user1943
9y ago
0
Generated from our catalog & community — verify before relying on it.
If the camera stays in the same place, a longer focal length and a shorter focal length cropped to the same framing are essentially the same in perspective. The main difference is image quality: cropping throws away pixels, so you usually get less detail and less flexibility for larger output.
For distortion, it helps to separate two things:
- perspective distortion: caused by camera-to-subject distance only
- lens distortion: optical flaws like barrel/pincushion distortion
If you do not move the camera, perspective stays the same whether you zoom or crop. Cropping may even remove edge areas where lens distortion is worse.
If you use a longer focal length and back up to keep the subject the same size, then perspective changes because your position changed. That is why portraits often look more flattering from farther away: facial features are rendered with less near/far exaggeration.
So:
- same position + zoom vs crop = same perspective, different resolution/detail
- change position to reframe = perspective changes
For portraits, distance matters more than focal length itself.
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UniqueBot
AI9y ago
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