Another option at a similar price is the Sigma 120-300 f2.8, this is supposed to have near identical AF speed and IQ to the 300 f2.8 prime, but with the flexability of a zoom. I do know someone who tested both a felt that the IQ of the zoom was better than the prime, it was sharper wide open!

Zooms have come a long way, I have heard that the Sigma 300-800 f/5.6 zoom is sharper than the Sigma 800 f/5.6 prime. Don't know why, a zoom has more elements making it more complicated.

I can only guess that new manufacturing methods (computer controlled griding, and polishing), new kinds of glass, and aspherics mean that modern zooms perform to a level never before imagined and yet can be produced at an affordable price.

It could be that the 800 prime is simply an older design, and were it to be redone, it would beat the zoom. Just look at wide angle primes. Most are old designs from the 80's (in the case of Nikon anyway) whereas wide angle zooms are usually from the past decade.

I will have a look at the 120-300mm. Other people have mentioned to me the Bigma but for me thats out the game due to it being relatively slow.

Ollie,

I would have thought VR would be the name of the game in aviation photography. Having looked at the exifs in Foxys pics he has gone down to 1/125 sec at 300mm + to achieve prop blurr.

Don

Yes VR would be usefull. I cant see any mention of Nikons F4 having VR though.

It does not, but 80-400 does.

It is just a thought as I do not know how you hand hold a 300mm at speeds of 1/200 sec and lower and get sharp pics. I certainly cannot.

Before someone jumps on this, by sharp, I mean fine detail is sharp when viewed at 100%.

Don

I have thought about the 80-400 but im not to sure about it. Again its not a fast lens and at times last year i could have done with a faster lens.

I second Bigma F2.8
Not having one myself but have heard a lot of good about it.
Even after a year of use, you should be able to salvage a good portion of your investment on ebay when disposing it.
I have Bigma 50-500mm and the only difference I see in comparison to Canon's top of the line L series, is the better color render with Canon's glass. Sharpness is equally good on both.