Summary: Well, I must start by sayingt hat this lens is amazing. I havent had the chance to compare it to the newer mark II but it takes really good images. I use it on a H sensor camera and the speed and lens combo is perfect. I get the 390mm at f 2.8 and there is no reason to use a higher f stop number. It is havy and i use it as a carry arowned lens for sports and wildlife. it works fine for me beeing an x triathlete but it gets to the heavy point at some times.
Great experience buying the lens on Ebay, just as advertised & had EBay ins
11 December 2011
Summary: I had read about the sharpness of pictures with this lens, as well as the overall quality and did lots of studying before making such a large lens purchase. I can tell you, it is well worth it. I primarily photograph wildlife, and it is unsurpassed in my estimation. It is light enough to use without a tripod, and I've gotten some great pics of birds flying with it, as well as quick point & shoot opportunities.
Summary: This lens is everything that they say it is. It does take a little getting used to, although I have to admit most of my blown shots are in low light and/or using a 2x teleconverter. The one day (so far) I went out with lens only and bright sun, autofocus was over 90%. I did a test shot with the 2x tele and a tripod. Had to lock the mirror up even though I have a good tripod. Seems that even the expensive lens mounts have some vibration in them.