A crop sensor is the hardware: a smaller sensor that takes a smaller rectangle out of the lens projection. A crop mode is a setting on a larger sensor that reads only part of it, and the cost is pixels rather than field of view.
Both words describe keeping the middle of an image circle. One is a sensor, the other a setting.
The sensor
A physical size, and the size names are published per maker rather than by any organisation. Twelve titles here print APS-C and seven the full-frame equivalent. A smaller sensor sees less of the same projection, so framing narrows for a given engraved focal length.
The mode
A setting on a larger sensor that reads a smaller area of it. The field of view narrows exactly as it would on the smaller sensor, and the file comes out with fewer pixels because fewer were read.
Where the distinction bites
Lens coverage. A lens built for the smaller format on a larger body illuminates only part of the frame; the mode is the maker’s answer to that, and it is published per body rather than implied by the mount.
Pixel count. The sensor costs you nothing in pixels — it has what it has. The mode costs you the part it does not read, and how much is stated in the body’s own documentation.
What neither changes
The engraved focal length of the lens, which is the same number in every case; and the f-number, which is a ratio and does not move with format or mode.
What people ask before they commit
Why would a full-frame camera offer a crop mode at all?
So that a lens built for the smaller format can be used without dark corners, and sometimes to gain frame rate by reading less of the sensor. Both are published per body, and the price in each case is the pixel count of the resulting file.
Is a crop mode the same as cropping afterwards?
Optically yes, in that both keep the middle and discard the rest. The differences are practical: the mode shows you the frame you are keeping while you shoot, and it writes a smaller file. Cropping later keeps every option open at the cost of doing the work twice.
Last reviewed 12 September 2026