When using a digital camera, if the chip is smaller than the film, the focal length of the lens will seem longer than those with a chip the same size of film.

• A. True
• B. False
• C. Not sure
• D. It depends on the lens

Answer: (A)

When the sensor is smaller than the film, the camera records a smaller portion of the image, narrowing the field of view. That cropping makes the scene look as if a longer focal length was used, even though the lens’s actual focal length hasn’t changed. In other words, the lens doesn’t physically become longer; the smaller sensor creates the appearance of a longer lens by reducing how much of the scene it captures. For example, on a typical APS-C sensor with about a 1.5x crop factor, a 50mm lens gives a field of view similar to around 75mm on a full-frame sensor. So the focal length appears longer because of the crop factor, not because the lens is different. If the sensor were the same size as the film, there would be no such effect and the focal length would match the actual lens specification.