Whoops! I should have read his post more carefully; I missed the "EF-S" part.
Would having a 400mm made for 1.6 crop sensors really save any appreciable size or weight? I thought those advantages were pretty much negated with the longer focal lengths.
In the olden days there was a big difference in size of lenses for 35mm vs 120 format, so I'm just assuming the same would be the case for APS-C and FF. I note that the EF-S 24mm/2.8 is less than half the weight of the EF 24mm/2.8.
It would be wonderful to have a lighter 400mm with perhaps even a larger aperture just for APS-C bodies.













