Why phones use equivalent focal lengths
Phone sensors are much smaller than a 35mm full-frame sensor. A short physical lens can therefore produce a familiar wide, normal or telephoto field of view. Equivalent focal length provides one shared reference for comparing those different sensor formats.
Equivalent does not mean identical
Two cameras with the same equivalent focal length can differ in perspective handling, depth of field, image quality, stabilization and processing. Perspective itself depends on camera position, while the equivalent number mainly describes framing.
Using crop factor correctly
- Multiply actual focal length by crop factor for the equivalent focal length.
- Use values from the same rear or front camera module.
- Remember that digital zoom applies an additional crop after capture.