Join Tim Grey for an in-depth discussion in this video What is focus?, part of Learn Photography: Autofocus.
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- As we start to delve into the topics related to focus in photography, one of the first questions, of course, is what is focus? Well, that's easy. Focus is focus. We all know what focus is, we know what a blurred image looks like. But how do we actually define focus for a photographic image? In general you can think of focus as representing relative contrast, or texture, or detail in the scene. Let's take a look at an example here so that we can get a better sense of exactly what that focus looks like, and start to recognize what focus versus not in focus looks like.
I'm going to enable the live view display of my camera here, so we can take a lot at the LCD. And at the moment it might almost look like this image is in focus, that's it's sharp. That the scene, the camera that I'm photographing here, actually looks appropriate. But if I zoom in a little bit we'll quickly see that we do not have good focus. In fact, the focus is rather poor in this case. We see the contrast edges are blurred, we have a transition from the stripes, for example. I think that's a really easy area to see focus versus not in focus.
And the edge of the stripe transitions across a relatively large distance. So we're going from silver stripe into the brownish-black color of the body of the camera, and the distance of that transition is relatively large, all things considered. And as we adjust our focus, if we go more out of focus the transition starts to blur even more, so we're transitioning across an even larger distance, we're seeing less contrast, less texture, less detail. But as we start to come in to sharp focus, we see that we have nice, crisp contrast.
The edges where we transition with strong contrast are very crisp, transitioning over a very short distance. Of course, in many cases, the camera is taking care of focus for us relatively automatically, or in some cases entirely automatically. That can make our job as a photographer a little bit easier. But it's still critically important to recognize what good focus looks like, what a blurred image or a non-focused image looks like so that we can evaluate the scene, evaluate our photographic images, and more importantly, achieve exactly the focus that we're looking for in our images.
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