> I always understood that for a telephoto lens you wanted the f-stop number to be higher, I suspect you are confusing f-stop (ratio of aperture diameter to fo

> I always understood that for a telephoto lens you wanted the f-stop number to be higher, I suspect you are confusing f-stop (ratio of aperture diameter to focal length) and focal length ("zoom"). Also the f-stop marketing is annoying to me - the f/2.4 aperture on an iPhone lens is probably equivalent to like f/22 on an FF lens for most purposes.