Simon97: On a proper gimbal mount, the mass of the lens helps with vibration. Should be similar in weight to a 600 f/4. I rather have a 600 f/4 because the 800mm lens can be too long in some cases. f/4 is faster and can be matched up with a quality 1.4x TC for 840mm/5.6
If I had my druthers I would like to see the 800mm made in a f/4 but I understand that would increase the weight about 5-7 pounds just in glass, LOL oh well I guess the f/5.6 will be just fine?
RBudding: VR? Who would want to hand hold that thing? It belongs on a gimbal head.
I changed out my Nikkor 600mm lens mount with a Really Right Stuff replacement and use there Telephoto support and it has corrected a lot of vibration in high winds even with using the Carbon Fiber lens hood mounted in 35-45mph gusts shooting waves crashing onto light houses as low as 1/60th with no issues
Apewithacamera: Just imagine how hot that lens will get outdoors under the sun. Yeeeouch!
Actually both Canon and Nikon have done studies on molecular shifting of the materials used under extreme temp change and that's one reason they are made out of a high tech alloy where steel would change shape to much just in 30 degree F differences but the change in these alloys are so subtle in 100 degree changes that image quality is not a concern and you should acclimate any lens to the temp changes gradually before using it for long periods of time and if your out doors shooting it will adapt with changing temps.
FTW: Well, it are good and clean pictures, but at 600$ for the place at the Olympics and an estimated ( I put the bar low) 12000$ for the lens, the pictures can be good. There is not much more stuff in an 800 mm lens than in a 300, so what makes the price of it then. You might say the low amount sold. But, if it is at reasonable price, they will sell more too. On the other end, just a few need that and many would like to have it, but can't afford it. If all on this planet was worth the price you pay for ....
As well in that these lenses are hand assembled and meet more tighter tolerances than a Nikkor DX lens, also the cost of Optical glass and coating procedures are not like just going down to your local glass supplier and buying a chunk of glass and grinding the correct contours, every lens has to meet specific quality control checks and inspections, the housing must be machined true and square to very tight specs, and this doesn't happen on a production line scale, I think Nikon, Canon have done very well in these monster telephoto lenses in quality and performance, and it takes years to develop the optics and to produce the outcome of the glass quality, if was that easy then why isn't everyone making them? and if anyone thinks it is easy then I welcome all the critiques to invest there Millions to invest in the property, building and machinery and employees to operate them and support them and lets not for get the side money you have to invest in having a business to make it.