For Nikon and Sony, lens length settings need to be multiplied by what factor for digital focal length equivalent?

The correct answer for Nikon and Sony is 1.5. This factor is known as the crop factor, which converts the focal length of lenses used on cameras with an APS-C sensor size to their full-frame equivalent.

Nikon and Sony both utilize APS-C sensors that have a crop factor of approximately 1.5, meaning that if you have a lens of a specific focal length, you can multiply that focal length by 1.5 to obtain the equivalent focal length when compared to a full-frame (35mm) camera. For instance, a 50mm lens on an APS-C Nikon or Sony camera will give an equivalent field of view of about 75mm, as 50mm multiplied by 1.5 is 75mm.

Understanding this concept is crucial for photographers who aim to utilize their equipment effectively and achieve the desired framing and depth of field in their images. It allows for more precise planning when selecting lenses for particular shooting scenarios, especially when transitioning from one camera body to another with different sensor sizes.