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What does it mean when a photo is "sharp"?



In photography we try to take "sharp" photos. In general, this means that the subject should be in focus, with clean lines, sharp details, and no (unintentional) blur. It is a combination of precise focusing, a static camera and the characteristics of the lens used.

One thing to keep in mind is that there are two types of sharpness: There is an official optical measure (it is called acutance) that gets all kinds of complicated fast, and there is a perceived sharpness that photographers mostly want , The latter is addressed today, although there are some overlaps with the optical sharpness.

So, let us in.

What is sharpness?

As defined above, the subject is a sharp image of the image ̵

1; or the parts of the subject you want – with every detail sharp and clean in focus. Below is one of my favorite examples.

The main theme of the photo is Kat's eyes; They are so sharp that you can see the individual eyelashes, even if the focus on her face wears off. Just compare the sharpness of her eyes with the slight blurring of her ears and the blurry background. I know that I pull with my own horn, but it's a pretty good example of the classic "portrait look".

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Here the image is sharp throughout the frame, from the rocks in the foreground to the lighthouse in the background , The motion blur in the rocks is just one element of long exposure photography.

RELATED: How to Take Good Long Exposure Photos

In both examples above, sharpness is the result of accurate focusing, a static camera, and the lens and its settings. Let's take them one after another.

Precise focus

Accurate focusing is probably the most important factor for taking sharp pictures. If you miss the focus on a small scale, it will affect your image and not save a lot of work in the mailbox. I love the photo of an old man putting up his fishing gear, but I missed the focus.

Even though I was just a little bit away – somewhere between his hands and his sweater it's focus is resting – the photo is now pretty much useless for anything other than teaching people to not focus to miss. Much more of this picture is blurry, but because her eyes are sharp, the picture works. Although the rest of the subject is quite in focus, the fisherman's face is not and the photo does not work.

A static camera

There is no camera movement for a sharp image. This means one of two things: Either you shoot with a slow shutter speed to freeze the movement, or you use a tripod to lock the camera.

Which option you use depends on the type of photo taken. You need a fast shutter speed for a portrait. For a landscape, you can choose either a fast shutter speed or a tripod if you want to use a longer shutter speed.

The features of the lens used

Lenses are far more important than your camera It depends on image quality. Even the simplest SLRs can take great, sharp photos, while a bad lens makes the camera worthless by ten.

In general, good lenses – that is, expensive lenses – provide a higher sharpness throughout the image that photographers refer to than "edge-to-edge sharpness." With cheaper lenses, images are likely to be taken where the center of the image is sharp but the edges are out of focus.

Better lenses also have less optical distortion or chromatic aberration. You can see a small loss of edge sharpness in the image below of a newspaper. The text block on the left is in the center of the image, while the block on the right comes from the edge. I used a Canon 50mm 1: 1.8 for this review.

Lenses do not have the same quality throughout, which can add to the confusion. Most lenses have a "sweet-spot" surface, which is the sharpest. Normally the value is between f / 5.6 and f / 16, depending on how the lens is designed.

To get an idea of ​​how sharp the lenses are and when they are with you. Look at the reviews on DxOMark.


So you have it: Sharpness is sharp and a decent lens – as long as you do not fumble the camera while recording.


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