Does holding a camera farther from your face change focal length or field of view?
Asked 11/23/2011
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I’m moving from a Nikon APS-C DSLR used at the viewfinder to a Micro Four Thirds camera that I often frame with the rear LCD. I also switched from a 35mm lens on APS-C (about 52.5mm full-frame equivalent) to a 14mm lens on Micro Four Thirds (about 28mm equivalent).
Because I’m now holding the camera several inches farther away from my face instead of against my eye, I’m wondering whether that changes how the image behaves relative to my own viewpoint. Does the lens effectively act less wide because it is physically farther in front of me? More generally, how do focal length, angle of view, perspective, and camera position relate to each other?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
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The focal length and sensor dimensions form a triangle (or, rather, a pyramid, but horizontally or vertically a triangle), the angle of which is the angle of view. When you move the camera, you're not changing the angle of view, but you are changing the perspective.
That will change the framing, and will be the case that certain different framings line up with the angle of view provided by other focal lengths from different positions — but the perspective is simply a function of where you (or the camera) are located. This is what people mean when they say "you can't zoom with your feet". Changing location inevitably changes perspective in a way that changing focal length does not.
Originally by user1943. Source · Licensed CC BY-SA 4.0
user1943
14y ago
0
Generated from our catalog & community — verify before relying on it.
Holding the camera farther from your face does not change the lens’s focal length or the camera’s angle of view. Those are determined by the actual focal length and the sensor size.
What does change when you move the camera is perspective. Moving the camera forward, backward, or sideways changes the apparent spatial relationship between near and far objects. That can make framing look different, but it is not the same as changing focal length.
This is why people say you can’t truly “zoom with your feet”: walking changes perspective, while zooming or changing lenses changes angle of view from the same position.
So your 14mm on Micro Four Thirds still gives the angle of view of roughly a 28mm-equivalent lens, regardless of whether you hold it to your eye or out on the LCD. If you move the camera to recompose the subject, the framing may resemble what another focal length would give from a different position, but the perspective will be different.
In short: focal length + sensor size set field of view; camera position sets perspective.
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