nikon has had a 800/5.6 lens out for a while, canon just joined them with their release. i am curious to know how they justify offering it...it especially for so much..? not trying to say they are irrational, or that everything needs to be, i have toys, i enjoy toys, i buy them often... i have a canon 600/4 and with a 1.4x i get an 840 5.6 that still has great optics. many pros, especially bird and wildlife photos have tele-converters, so it seems like it would be hard to sell the 800mm lens.
thanks