I have had the D800 for over a month...and got the D800e a couple weeks ago. I have had zero problems getting sharp images. These cameras require glass that is equally resolute. Unfortunately, I am afraid that is not the case with your glass. Borrow a 70x200 VR F/2.8 II, use a tripod and shoot. I doubt you will find a camera with better detail and sharpness. I am blown away.