Not sure why they stopped making this, sure it looks big and chunky, but so does the Sigmortar-launcher and they sell.
If only I knew how good the IQ was, it might make a really good birding-lens (mounted on the back of a truck, of course).
Still, it's cheaper than a second-hand 200/2 or 400/4DO.
http://www.ebay.com.au/itm/230698425121
http://www.canon.com/camera-museum/c...0~600_56l.html