It's not easy, with 70 year old eyes, focusing a dog that is subject to move a lot using 105/2.5 Ai-S mounted on a D200. In fact, I don't think I want to try it again, and haven't since! I like the lens well enough, and the camera body, but the combination is way more difficult than I'm up for. As the thread title says, I was lucky to get anything.
