In photography, we strive to capture a sharp image Overall, this means you want the subject to be in focus with crisp lines, crisp details, and blurring (unintended). It’s a combination of fine focus, a steady camera, and the characteristics of the lens it uses.
One thing to note is that there are two types of sharpness: There’s a formal optical scale (called sharpness) that gets all sorts of fast complications, and there’s a noticeable sharpness, which is what photographers mostly want. We’re dealing with the latter today, although there is some overlap with visual acuity.
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What is the sharpness?
As defined above, a sharp photo is one in which the subject of the photo – or parts of the subject you want – are in perfect focus with every detail crisp and clear. Below, is one of my favorite examples of this.
The main picture “theme” is the cat eyes. She is so sharp that you can see the individual eyelashes even though the focus fades on her face. Just compare the sharpness of her eyes with the slight blurring of her ears and the blurred background. I know I play my trumpet, but it’s a very nice example of a classic ‘vertical look’.
Let’s look at another example, this time from a landscape.
The image here is sharp throughout the frame, from the rocks in the foreground to the lighthouse in the background. Rock motion blur is just an element of long exposure photography.
In both examples above, the sharpness is the result of fine focus, still camera, and lens and its settings. Let’s take them one by one.
Precise focus
Accurate focus is arguably the most important factor in capturing sharp photos. If you lose focus, even a tiny bit, something will appear with your photo and no amount of work in the post will save it. Love the photo below of an old man setting up his fishing gear, but I missed focus.
Although I was a little distant – somewhere in his hands and jacket where focus lies – the image is now largely unusable for anything but teaching people not to miss focus.
Compare the photo to the Cat photo above. Much of that image is blurry but since her eyes are sharp the image works. Here, although the rest of the topic is very much in focus, the face of the hunter is not, and the image does not work.
Use a camera tripod
To get a sharp image, there can be no camera movement in the image. That means one of two things: Either you shoot at a shutter speed enough to freeze action or use a tripod to lock the camera.
The option you use depends on the type of image you are trying to capture. To get a selfie, you’ll need to use a fast shutter speed. For landscapes, you can either use a fast shutter speed or a tripod if you want to use a longer exposure time.
The specifications of the lens you are using
Lenses are much more important than your camera when it comes to image quality. Even the simplest DSLR can take great, sharp images while a bad lens will render the camera useless.
In general, good lenses – meaning more expensive lenses – provide greater clarity throughout an image, and are referred to by photographers as “edge-to-edge sharpness”. Cheaper lenses will likely take pictures where the center of the image is sharp, but the edges are blurred.
Better lenses also have less optical distortion or chromatic aberration. You can see a slight loss of sharpness in the photo at the bottom of a newspaper. The text block is on the left from the center of the image while the block on the right is from the edge. I used a Canon 50mm f / 1.8 for this test.
The lenses don’t have the same quality across their full range, which can make things even more confusing. Most lenses have a “pretty spot” aperture where it’s at its most extreme. It’s usually somewhere between f / 5.6 and f / 16 depending on how the lens is designed.
To get an idea of how sharp your lenses are and when they’re at their best, check out reviews on DxOMark.
So here it is: sharpness is focus plus a suitable lens – as long as you don’t get stuck in the camera while taking the photo.
