How to Use the Camera Field of View Calculator
The same 50mm lens frames a noticeably different field of view on a full-frame camera versus a crop-sensor camera. This calculator takes your sensor size and lens focal length, then computes the real horizontal field of view, the 35mm-equivalent focal length, and the resulting compression tendency.
The smaller a sensor is compared to full frame, the more the edges of the lens's projected image get cropped out, narrowing the field of view — similar to using a longer lens. This is expressed as a crop factor: APS-C sensors are typically 1.5x-1.6x, and Micro Four Thirds is about 2x. A 50mm lens on APS-C, for example, frames roughly like a 75-80mm lens would on full frame.
The longer the equivalent focal length, the stronger the perspective compression. Under 35mm, the wide field of view exaggerates perspective; around 70mm looks close to natural human vision; and beyond 135mm, the background appears to sit closer to the subject — a compression effect widely favored in portrait photography.
Frequently Asked Questions
A sensor smaller than full-frame only captures the center portion of the image the lens projects, so the effective field of view narrows — similar to what you'd get from a longer lens. That's what the equivalent focal length represents.
It's the effect where a telephoto lens shot from farther away makes the background look closer to the subject than it really is. The longer the equivalent focal length (roughly 135mm+), the stronger this effect, which is popular in portraits for a flattering, compressed background.