In my humble experience, nature macro photography comes down to the factors that “normal” photography typically does. Know your camera and peripheral equipment and know your subject. Lighting and composition. At the risk of oversimplifying, that’s about it. The big challenge or “difference” of macro photography, working with the depth of field, is not even all that peculiar to macro except for the extreme shallowness. That is the fun (and sometimes the “fun”) part, especially as magnification ratios get higher and the razor thin depth of field diminishes further. The photo above features a micro moth — the smallest moth that I myself have photographed — and shows what happens when a tiny subject meets tiny depth of field.
It is an old photo, and one of the unfortunate things about the reverse lens set up is, the camera cannot record certain information. Somebody uninterested in manually recording the info (e.g. focal length and aperture size – which mind you, with a reversed lens won’t be precise, anyway), that somebody will eventually forget particulars. So just call me somebody. That said, my best, relatively confident guess is that the moth was around 4mm in length, give or take, and probably shot at a 3:1 ratio or higher. In this type of scenario, the camera has to be held precisely.
I did fairly well, but I ultimately did not get the shot I wanted. The critter was working against me as it was not exactly stationary. Working with a razor-thin depth of field and a moving target can be impossible at times. In this case I managed to get the lower part of the wings into (mostly) sharp focus, while the head is leading out of the focal plane; if the moth stood still, I probably could have got the job done (though with my shaky hands, you never know).
There’s not a lot to be done in this kind of situation unless you place the moth into a controlled environment, and even then you might have to chill it or take some other measure, with which I’m not familiar, to keep it still. Occasionally I will move or prod an insect into a more amenable place for shooting, usually something like a caterpillar that is easy to replace in its original setting. Typically, however I am not interested in that option. So the biggest help working with moving targets for me has been repetition. For less but still active subjects, like flies or bees feeding on a flower, I have some muscle memory built up and anticipating where they will be has become easier if not easy. If they are moving too quickly or erratically, I’m probably stabbing in the dark and nothing but luck is going to make up for any-sized difference, micro or not.