Crop factor is a term used in photography to describe the ratio of a camera's sensor size compared to a standard 35mm film frame. It helps photographers understand how the field of view changes when using different sensor sizes. A smaller sensor, like those found in many DSLR and mirrorless cameras, will have a higher crop factor, which effectively multiplies the focal length of a lens. For example, if a camera has a crop factor of 1.5, a 50mm lens will behave like a 75mm lens in terms of field of view. This means that the image will appear more zoomed in compared to using the same lens on a full-frame camera. Understanding crop factor is essential for photographers to achieve the desired composition in their images.