Crop Factor or form factor is a term used in photography . It gives diagonal length ratio between two formats.It is an important factor in Digital Photography. Previously we discussed about various image Sensor Size and Field of View. In case of Digital Photography, Crop Factor is more important and dependent on Sensor size than was in Film Photography.
What is this Crop Factor actually is ?
Since the Sensor Format (practically the size of sensor) and focal length are directly related in Optics, Crop Factor is used to calculate what focal length lens would need to be used to focus an object with different sensor sizes at the same distance.
With DSLR cameras based digital photography world, the format of 24 mm × 36 mm is used as The Standard format. The diagonal length of the photosensitive surface of the image sensor multiplied by Crop Factor is field of image. As it can be guessed, for this Crop Factor, cameras with small sensors will be able to take more zoomed view than with a full sized sensor camera.
Instead of specifying the Crop Factor, we classify the camera lenses based on their angle of view for each format as Wide Angle Lens or Telephoto lens. In this topic of Crop Factor, as a corollary it must be mentioned that a telephoto design affects the angle of view.
Other notes on Crop Factor
The image sensor of a DSLR camera has several established Crop Factor of 1.5 to 1.6 times smaller than the usual film camera’s small format (24 mm × 36 mm), that is 15.7 mm × 23.5 mm (so-called APS-C format). For a lens with 50 mm focal length, the image sensor is able to view only a part due to this crop factor. So, in practical usage, paradoxically comparing to a 9 × 13 inch prints of a photo shot with same lens on a small screen with that from a digital camera, as if a longer focal length lens was used. So, basically for this defect - Crop Factor, we are getting an enlarged image with more details. This Crop Factor is the sole reason why, with a bridge digital camera you can take a kind of Macro photograph.