ultra sharp wildlife pics

[BackdoorArts]

I agree that there's a bit of movement blur, but it doesn't mean it's not fixable.

For this one instead of using Adjust AI I used Topaz Sharpen AI with the "Stabilize" function. Photoshop has Shake Reduction in the Sharpening menu, but I couldn't replicate it. The rest is Camera Raw and added blur to smooth out some of the background.

 

[STM]

There are any number of reasons. You can have subject or camera movement (which is a biggie if you are using a long lens), the AF choosing a different focus spot rather than the one you want, misalignment inside the lens itself, choosing a high ISO to get a high shutter speed, etc. I suggest you use a tripod and a gimbal head for your shots using a long lens, especially a 600mm one. If not a tripod, at least a monopod. My 600mm f/4 AIS Nikkor is my go-to lens for nature photography, but at 14 pounds (lens alone) and over 2 feet long, it is just not hand holdable, especially since it is manual focus. But put it on a sturdy tripod with a gimbal head and it is a dream to use!