How digital zoom affects image detail
Digital zoom usually crops the center of the camera image and enlarges that crop. In this simplified model, effective width and height are divided by the zoom factor. Because image area uses both dimensions, effective megapixels fall by the square of the zoom factor.
Digital zoom and optical zoom are different
Optical zoom changes the image reaching the sensor through physical lenses. Digital zoom works after the sensor has captured the scene. A phone may combine telephoto lenses, sensor cropping and processing, so real results can be better or worse than a single crop calculation.
Use the result as a planning estimate
- Start from the native dimensions of the camera you plan to use.
- Compare moderate and extreme zoom levels before shooting.
- Use better light and steadier support when the estimated source detail becomes small.