Full-frame vs Crop-sensor comparison :  Depth-of-field & Perspective

When the differences between full-frame and crop-sensor cameras are discussed, there is an inevitable question about whether the crop sensor multiplies the focal length. Whether a 50mm lens on a crop-sensor acts like a 75mm lens (on a 1.5x crop sensor) or 80mm lens (on a 1.6x crop sensor). The answers given on the photography forums are confusing - yes, the focal length effectively increases. No, it doesn't. Two answers that are polar opposites. The discussion (which tend to devolve into arguments) are  Read more inside...