Focal length calculation – how does it work?
Focal length affects the magnification, field of view and depth of field. Although a long focal length means high magnification, it also means a smaller field of view and a shallower depth of field. To determine the equivalent focal length for a digital camera compared to a 35 mm camera, you need to carry out a few calculations. Each digital camera has a 35 mm equivalent figure. For the Nikon P-6000, for example, the 35 mm equivalent figure is 28 – 112 mm. Since the Nikon p-6000 has a digital focal length of 6 – 24 mm, this results in a factor of 4.66 (28 mm divided by 6 mm). This factor or the 35mm equivalent focal length is usually stated in the camera’s user manual. In this case, the equivalent focal length is the adjusted focal length of the digital camera multiplied by the factor 4.66. Example: The Nikon P-6000 is set to a focal length of 14 mm. 14 mm x 4.66 = 65.2 mm focal length equivalent for a 35 mm camera. To obtain the entire 35 mm equivalent focal length from your digiscopi
