For the first time yesterday, I used the Nikkor 50mm prime f/1.8, which doesn`t autofocus on my D40. There are a lot of stray cats in my area and I stumbled on a couple of them chilling out in a pine tree that afternoon. Here are a couple sample photos with a few questions. 1/200sec, f/1.8 The face of the cat on the left is is seems pretty sharp, but the one on the right isn`t. It was probably four inches further away from the camera. Is the depth of field that shallow on f/1.8? Or did I just accidentally leave a few inches of air in front on the cats in focus too? ----- 1/80sec, f/3.5 Here, I`ve gotten things the other way round: it`s now the cat on the left that`s out of focus (after it decided to stick its head forward an extra two or three inches). But the aperture is now down to f/3.5. Presumably that means a much bigger depth of field, which means I`d left a fair bit of empty space behind the cats in focus, right? Generally speaking, is there a guide about how great a depth of field I`ll have with each f-stop? Is there a table that says how many centimeters/meters you`ll have in focus on each f-stop? How much does this vary between lenses? Does anyone have any tips, beyond just practicing a lot, for learning to get sharp manual focus? I`m not sure what this could be, but maybe someone can recommend some useful exercises. Oh, and I also took some photos that are just slightly fuzzy round the edges and I think it creates a dreamlike quality. If you want an out-of-focus photo like this, does it make a difference whether you do it in camera or on the computer later?