(c) Rob Sheppard
I love close-ups. They truly bring you into a different world that we normally don't see. And I am not talking about super close work, either. Any time we get in close to a natural subject, we are looking more deeply at the world around us in a way we usually don't do. In a way, the act of close-up photography gets us to pause and observe details that we might otherwise pass on by.
One challenge that comes from close photography is the focus point. When you are close, depth of field is very narrow, no matter what f-stop you use, so the actual point of focus becomes very, very important. This is even more critical when you play with extremely shallow depth of field as I often like to do.
(c) Rob Sheppard
Autofocus can be really challenging when you are up close. I will usually shoot manual focus when I am doing any close-up work with any lens. The challenge the camera has is that depth of field is always very limited (and gets less and less the closer you get). Yet there are many points where the camera can focus and it will "choose" its focus point rather arbitrarily - often visually the wrong point for the subject and the composition.
My preference is this:
1. Change the camera/lens to manual focus
2. Roughly focus on the subject to get a basic distance
3. Then without changing the lens' focus, move the camera toward and away from the subject until the right point is in focus
4. Take the picture
5. You can be careful as you do this so you do not have camera movement during exposure that will make the image soft.
Both of these close-ups are from the redwoods. The first is in the Dicentra or bleeding heart genus and is often called squirrel corn when it is so white. The second is a redwoods sorel flower.