Getting sharp images: every photo technique you need to know starting out

jmeyer | Photography Tips | 15/01/2013 11:30am

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Best Ways To Get Sharp Images: Diffraction

One of the first things that most people learn about photography is that using a small aperture creates more depth of field so more of the image is sharp. This is true, but at very small apertures the impact of a phenomenon called diffraction becomes apparent.

Diffraction is the bending of light rays as they pass over the edge of the aperture. The smaller the aperture, the greater the proportion of light rays being bent.

Bent light rays don’t focus at the right point (on the sensor) and this means that this part of the image will not be sharp. The greater the proportion of unfocused light, the softer the image will be.

Even though the depth of field gets more extensive as the aperture is closed down to a very small size, the sharpest part of the image is not as sharp as it is in an image taken at a moderate aperture setting.

You can find your lens’s optimum aperture by shooting an object with lots of detail at every available aperture with the focus set to the same point.

Then examine each image at 100% on screen and find the image in which the focus point is sharpest. You will notice that the image focal point gets sharper as the the aperture is closed down from maximum before it starts to get softer again.

In many cases a mid-range aperture of f/8, f/11 or even f/16 produces appreciably better images.

$Best Ways To Get Sharp Images: Diffraction$

f/8 at 100%

$Best Ways To Get Sharp Images: Diffraction$

f/16 at 100%

$Best Ways To Get Sharp Images: Diffraction$

f/36 at 100%

Once you have discovered your lens’ optimum aperture, use this wherever possible and focus carefully to make maximum use of the depth of field available. The hyperfocal distance focusing technique can help with this.

If you need more of the image to be sharp then you could try focus stacking. This technique involves shooting two or more images taken at the optimum aperture, but with different focus points. These images can then be combined to create a single image that is sharp throughout. See here for more about focus stacking.

PAGE 1: Best ways to get sharp images – Focus
PAGE 2: Best ways to get sharp images – Freeze the subject
PAGE 3: Best ways to get sharp images – Keep the camera still
PAGE 4: Best ways to get sharp images – steady the tripod
PAGE 5: Best ways to get sharp images – get a remote release
PAGE 6: Best ways to get sharp images – mirror lock-up
PAGE 7: Best ways to get sharp images – diffraction