Thank you for your feedback, I can't afford more than the 400mm f5.6 in terms of price and also weight/size, I cant imagine carrying anything bigger than this. I am in no way pro or near to pro wildlife shooter. I have been using it for over 1 month, satisfied with it so far. Most of the times I attach it with my 1.4x II for small birds or animals at far distance, the results are satisfactory. I will post some birds shot soon. Recently I have been trying something out of my comfort zone (landscapes) and I am enjoying it. Thanks once again.