Canon's 600mm F4 IS super telephoto lens is the ultimate tool for sports and wildlife photography. A quiet micro ultrasonic motor powers the world's fastest autofocus that gives the user the option of manual override, recalling a preset focus position or limiting focus distance to prevent hunting out of range. Ultra low dispersion glass and fluorite elements create high definition images with excellent contrast. Fast f/4 maximum aperture allows high shutter speeds in less than ideal lighting and facilitates the use of teleconverters. Optical image stabilization designed specifically for this lens operates in two user selected modes. Dust and moisture resistant construction make it ideal for the outdoors.

This lens has approximately 12 times magnification when used with Canon's full frame 5D DSLR, approximately 16 times magnification when used with EOS 1D Mark II or Mark III, and approximately 20 times magnification when used with Canon's 20D or 30D bodies. At Amazon's current price, this lens plus a Canon DSLR body costs less than other brand's 600 F4 lens that sadly is not equipped with VR.

Increditable images. Forget the 600mm's, the images from this lens are very impressive, better than my other two Canon L lens - the f/2.8, 28-70mm zoom and the f/4, 300mm.
Before getting this lens in my hands, I thought I would be able to handhold shots using image stabilization. While this is possible, to get the full use from this lens a high quality tripod with Wimberley Mount is really a requirement. I have found this lens is really just too big to reasonably handheld. So unless you know a machinist, expect to spend another $1400. This adds not only to the price, but also to the equipment that you will need to carry to your shooting location, which brings up my next point.
In my research before getting this lens, numerous writers were complaining about carrying this lens to location. In my personal experience (I'm a 62-year-old retiree) I have not found this to be a problem. Yes it is heavy, but easily carried by the handle or inside a Lowes backpack if going a greater distance.
It should be noted that once you have all this equipment carried to a location, you are pretty much restricted to just taking pictures with your 600mm lens. Carrying this lens is a full time job requiring all your attention.
And taking about attention, you will attract a lot of it. Everyone, yes everyone will take notice of you, which as far as I am concerned is never a good thing, especially if you find yourself isolated along with some bad guys who realize the value of the equipment you are carrying.