Join Tim Grey for an in-depth discussion in this video Employing autofocus one shot vs. continuous, part of Learning Photography: Autofocus.
- Naturally, in most cases at least, it's relatively important to establish good focus for the subject that you're photographing. And the most convenient way, I would say, to accomplish that is through autofocus, letting the camera do as much of the work as possible. That's especially helpful or important when we have a moving subject, a more complicated photography scenario. But even when we're photographing a stand-alone still subject that's not going anywhere it can be very helpful to use autofocus, at least to establish your initial focus.
And it's certainly convenient to employ autofocus. But there are a couple of issues that you'll want to take into account when it comes to autofocus. First off, I'm going to enable autofocus so you could see that my image was not in focus in terms of the camera setting itself. And so, I'll go ahead and enable continuous autofocus because that is helpful for situations where I have a moving subject, not the case here, but let's consider continuous autofocus in the role that it might play in your autofocus when you're establishing focus for a subject.
With continuous autofocus, you can see I'm right now focusing on the lens of this camera in front of me. You can see the focusing point. And as I move my camera, so I'm adjusting the direction that I'm pointing the camera, going off into the background here. And you can see I'm establishing focus onto that background, but now the camera is completely out of focus. But as I come back into that camera, getting the camera back into my focusing point, you can see that the camera is adjusting that focus automatically. That's very convenient for situations where I have a moving subject and I want the camera to adjust the focus based on the moving subject, based on the relative distance to that subject as the subject maybe moves back and forth, closer and further away from my lens.
But in a situation like this, continuous autofocus can be a challenge. I have a subject that is not going anywhere and I might want to actually set my focus and then recompose. So let's go ahead and disable my continuous autofocus so that I'm taking advantage of what's called one shot autofocus. In other words, I'm establishing my focus and then leaving it where it is so I can now recompose. So I'll go ahead and establish that focus right on the front of the camera here.
And now, as I move the camera around, my camera around in this case, you'll see that I am not adjusting the focus. So I have established my one shot autofocus. I've set my focus to a specific distance. And now, no matter how much I move my camera around, I'm not changing the distance at which I'm focusing. That enables me to establish focus and then recompose. So I've established my focus on the front of that camera. And now, maybe I want to just recompose the scene a little bit, maybe something like that, for example.
Of course, there is an important caveat here. I set my focus based on a specific distance to the subject. If I change that relationship, if I move the subject or if the subject itself moves, or if I move my camera further away or closer to that subject, that's going to change the relationship. It's going to change whether or not the subject I actually focused on is going to remain in focus. And so, you need to pay attention to your distance to the subject. As I'm recomposing, it's perfectly fine to adjust the angle at which I'm pointing my camera, for example, as long as I'm not going too far, depending on how much depth of field I have.
But I do not want to change my position. I would not want to back away from the subject or move closer to the subject unless I'm then going to adjust my focus setting, because again, that focus is based on a specific distance from your lens to the subject. So there are some limitations obviously to take into account when we're establishing focus, establishing depth of field. But the key thing is to keep in mind that we can use autofocus to our advantage. We'll want to choose between continuous autofocus versus one shot autofocus, depending on the nature of the subject that we're focusing on.
Photographer and educator Tim Grey explores these questions and more in this exploration of focus and autofocus. And because sharpness isn't everything, Tim also details scenarios where blur can have more impact.
- What is focus?
- Calculating depth of field
- Looking at focus limitations
- Employing autofocus one shot vs. continuous
- Using manual focus
- Setting and choosing focus points
- Controlling depth of field
- Using intentional blur and bokeh
- Finding focus while panning