The Northrup video (thanks KarimNassar for posting) got me thinking about the following math to match a crop sensor to an FF sensor camera (this was also helpful: http://www.josephjamesphotography.com/equivalence/#introduction ): Multiply the focal length by the crop factor Multiply the f-stop by the crop factor Divide the ISO by the square of the crop factor The first two equations deal with the difference in scale. The physical aperture (light opening, "entrance pupil") will be exactly the