For a modest $11,599 + tax B+H is willing to sell you a Canon EF 800mm f5.6L IS
Despite the price tag it's quite a tempting lens. For one thing it's also a lot lighter than the 600mm f4L IS lens, while being around the same size (9.9 lbs vs 11.8 lbs), has an intrinsic focal length close to the 600mm + 1.4x teleconverter, and will be shockingly sharp without the converter or be an 1,040mm f8 lens with it.
Downside ? The minimum focus distance is 19.7 ft, so that's an 0.14x magnification at the closest range. The values for the 600mm f4 are 18.2 ft and 0.12x. So while you get a little extra magnification at closest distance you need to step back about a foot and a half. Of course, if you never get to within 20 feet of your subject this point is largely moot and the 800mm looks like an excellent option, modulo the price.
See Canon's own comparison between 500/4, 600/4 and 800/5.6.
Despite the price tag it's quite a tempting lens. For one thing it's also a lot lighter than the 600mm f4L IS lens, while being around the same size (9.9 lbs vs 11.8 lbs), has an intrinsic focal length close to the 600mm + 1.4x teleconverter, and will be shockingly sharp without the converter or be an 1,040mm f8 lens with it.
Downside ? The minimum focus distance is 19.7 ft, so that's an 0.14x magnification at the closest range. The values for the 600mm f4 are 18.2 ft and 0.12x. So while you get a little extra magnification at closest distance you need to step back about a foot and a half. Of course, if you never get to within 20 feet of your subject this point is largely moot and the 800mm looks like an excellent option, modulo the price.
See Canon's own comparison between 500/4, 600/4 and 800/5.6.