In article , Ron C
wrote:

As I see it, the problem is that the [consumer] interchangeable
lens industry focused on the 35mm format rather than a field
angle format. Vast numbers of users of that [35mm] format
equated focal length with wide/normal/(etc.) perspective lenses.

which is why they're using 35mm lenses as a reference point. it's what
people know.

~~
Thing is, that 135mm normal angle lens on my 4x5 camera produces
the same perspective as a 135 telephoto lens on my 35mm camera
when cropped equivalently. Thus, each 36x24mm segment of my
4x5 will be the same as a frame from the 35mm camera.

perspective is based on the position of the camera, not the lens used.

~~
With so many sensor formats these days, maybe the industry needs
to begin defining lenses by field of view rather than 35mm focal
length equivalents.

having so many sensor formats is exactly why they *can't* do that.