Which statement correctly describes how a crop conversion factor affects focal length?

• A. The conversion factor multiplies the focal length to yield the new focal length.
• B. The conversion factor adds to the focal length to yield the new focal length.
• C. The conversion factor divides the focal length to yield the new focal length.
• D. The conversion factor has no effect on focal length.

Answer: (A)

Crop conversion factor is a way to compare how sensor size changes the angle of view relative to a 35mm full-frame camera. To find the equivalent focal length on full-frame, you multiply the lens’s actual focal length by the crop factor. For example, with a 50mm lens on a sensor with a 1.5x crop, the field of view is like a 75mm lens on full-frame. The conversion factor doesn’t physically change the lens or its focal length; it’s a scale used to express how the view will differ between sensor sizes. Multiplication is the correct relationship because you’re scaling the real focal length to match the smaller sensor’s field of view. Adding, dividing, or claiming there’s no effect wouldn’t correctly describe how the view changes with sensor size.