I have a NEX-6 with a number of legacy lenses and the two NEX "kit" lenses. If I fit the 16-50 kit lens, setting it to 50mm, and view the image through the viewfinder, noting the width of the image, and then fit a Minolta 50mm lens on an MD-NEX adapter I note that the fov appears the same and the width of the image is the same as on the kit lens. Why is this? The other legacy lenses seem to behave in the same way.
Why is this? And why not? 50mm is 50mm and the adapter does not change anything (unless it is one of the very special adapters containing additional optics, like Metabones Speedbooster)