mikerae

I have used the 800 f5.6 since August 08 and the 500 f4 for three years and can give you my opinion on the two lenses I use. The image quality from the 500 is really excellent, however, the 800 is better. The best way I can describe the difference is that the RAW images from the 800 look as if they have been sharpened when compared side by side with the 500 images. The difference is small but still obvious to my eye. I was using the 500 with a lot with a canon 1.4 converter and the 800 image quality is very obviously much better than the 500 + 1.4.

Apart from the step up in image quality with the 800 it also has much improved Image Stabilization that has allowed me to get usable images that I would have found almost impossible with the 500. It is possible to get sharp images from the 800 at ridiculously slow shutter speeds (much slower than 100/sec) when hand holding or resting the lens on a car door etc. Hand held example

http://www.mikerae.com/life-in-the-landscape/52/otters-west-coast-scotland-and-hebrides#image173

resting on hide window example
http://www.mikerae.com/life-in-the-landscape/56/life-and-landscape-in-east-anglia#image181