In this video I break down crop factor the way it actually works—without turning it into a “full-frame vs crop sensor” debate. Crop factor isn’t some magical property of a crop sensor or a crop-specific lens. It exists because our whole industry uses full-frame (35mm) as the standard, so anything that isn’t full-frame gets compared back to it. That’s it. Most APS-C cameras are around 1.5x (Canon is 1.6x), Micro Four Thirds is about 2x, and even medium format has a “crop factor” (around 0.79) because it’s larger than full-frame. I also clear up the biggest misconception: focal length never changes. A 40mm lens is a 40mm lens no matter what camera you mount it on, because focal length is literally the distance from the lens’s nodal point to the sensor. What does change is your field of view (angle of view). So when people say “40mm becomes 60mm,” what they really mean is that 40mm on APS-C gives you the same field of view as a 60mm on full-frame. Then I get into the part people don’t talk about enough: crop factor and aperture. You only need to think about “equivalent aperture” when you change distance to match framing, because backing up increases depth of field. If you don’t move and you just crop the full-frame shot to match, depth of field and bokeh look the same. And yes—crop factor still applies even with crop-specific lenses, because it’s still about comparing field of view back to the full-frame standard.