Basics 3: Clarity and Focus

Now that we know how aperture manages the light coming into the camera, we need to step away from the exposure triangle for a moment and talk about clarity and focus, two closely related concepts which are often used interchangeably. Choosing what to focus on will drive many of the artistic decisions in our image. Our our audience’s attention will naturally be drawn to the clearest parts of the image, by adjusting focus (the camera control) we can determine which parts of the image are the most clear, and draw the viewer’s focus (attention) to part of our picture’s story.

Our goal is to make a clear image… usually. When we chose our subject we decided what we wanted to draw attention to. We set aperture to blur the background (or not) to emphasize our subect. We set exposure, either automatically based on the Aperture, or manually, to have enough light to capture our subject. The third element of drawing attention is making a clear image.

Focus fine-tunes the lens elements to get a sharp image on the camera sensir or film. Manual focus is adjusted with a ring on the lens. Autofocus is achieved by the camera when the body and lens support it. We won’t get into how it does that in this lesson. An in-focus subject will look natural and will have clearly defined details. Control over manual focus is entirely up to the photographer. Adjusting the focus ring, or physically moving forward or backward will affect the focus. With autofocus, the camera will provide one or more points that it will evaluate and move the lens focus for us.

We also talk about clarity in this lesson, becuase focus settings only get us hakf-way to a clear image. An out of focus lens will yield a blurry result, but even with perfect focus settings, we can still get blur from motion. Either the subject is moving, or the camera is (and we might not even notice). There is a third cause of blur from diffraction – that is an advanced topic for another post.

Clarity refers to an image wher the subject has clear details. They might also be described as having “hard” edges, or “sharp”. Our eyes and brains recognize details by detecting differences in color or texture. A set of black and white lines appear clear when the edges are clearly defined. When the edges are fuzzy, there is not a harsh transition from the black to the white. Images that are not clear may be described as “blurry”, or “soft”. Those qualities are not always negative. A softer focus might enhance a beauty portrait or it can emphasize the speed of a moving subject.

To restate, we get a clear image with a steady camera, a steady subject, and clear focus. Focus is controlled in camera. Outside the camera, focus is influenced by distance – macro photography is especially sensitive to small variations in distance. Motion blur can be managed by either stopping the motion of the subejct (not always in our control), stopping motion of the camera (using a tripod and a remote trigger, or

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