The rumored Canon second generation of 100-400mm f/4.5-5.6L IS USM II lens announced today, the major physical difference between the old and the new Zoom lens is use old / traditional rotating zoom ring and the push and pull zoom lens gone, If we look inside the Canon is giving Hybrid Image stabilization mode inside the new lens, that includes standard, panning, and during exposure only — and will give you approx 4-stops of stabilization.
Canon added One Fluorite and one Super UD element to insure super sharp images even when viewed at 100%, other noticeable improvement includes is the reduction of minimum focusing difference from 6.5 feet to 3.2 feet, 9 -blade circular aperture Electro-Magnetic Diaphragm for circular bokeh.
The old lens will cost you approx $1700 but the new lens with advance core specification will cost you approx $2200.
Pre-order this lens from B&H Store
