neuroanatomist is correct – the incident light per square centimeter @ the image plane is identical regardless of sensor type used.


Collar mount a 70-200 ƒ2.8 IS on a sturdy tripod ~ 25 feet from a quantitative test subject ( i.e. ruler @ 60° ). Now take following three test shots using the same shutter speed, aperture, and iso…


1. ~200mm on a 5D ( should have a ~0.8 ft * 2 range on your ruler)


2. ~153mm ( 200 / 1.3 ) on a 1D ( ~1.0 * 2 )


3. ~125mm ( 200 / 1.6 ) on a 7D ( ~1.3 ft * 2 )


human and camera induced variability aside, the result should be nearly identical framing and exposure across all three shots with significant differences in subject DOF, Bokeh.