Is My Image Sharp?

This is a question I've seen come up often on Reddit — and the answers are sometimes more revealing than expected.

Many of the images posted under that question were blurry. But looking at the unedited originals, it became clear why: a tiny portion of the image — sometimes as little as 5% — had been cropped out and enlarged several times beyond its natural size. At that point, the blurriness wasn't a mystery at all.

So how do you actually check sharpness?

These days, modern digital cameras often have higher resolutions than computer screens, which means you do need to zoom in to check for sharpness. But how much is the right amount?

The answer is 100%. Open your image on a good-sized monitor and zoom to 100%, where every pixel on your screen represents exactly one pixel in the image. At that level, an image is sharp if the point of focus — wherever you aimed the camera — looks crisp and clear.

If you want more of the scene to appear sharp, consider using a smaller aperture (higher f-number), which increases depth of field and brings a wider area into focus.

And if you zoom beyond 100%? Then multiple screen pixels are being used to represent a single image pixel, and the image will look soft or blurry no matter how good your camera or monitor is. That's not a sharpness problem — that's just the nature of digital images.