Why a small aperture isn’t always best
Most lenses have a minimum aperture of f/22, although some (such as macro lenses) offer an even smaller setting of, say, f/32.
But why is the minimum aperture rarely listed alongside the focal length, as its maximum aperture is?
This is because the smallest aperture is rarely recommended to be used, as this setting leads to softer, lower contrast images caused by an optical phenomenon known as diffraction.
Diffraction occurs when light waves entering the lens are ‘bent’ by the hard edges of the aperture blades.
Every aperture setting causes this, but the bending is generally minimal. However, as the apertures get smaller, the effect becomes more significant.
At the smallest aperture, the light waves are bent and spread out so much by the aperture blades that the image appears fuzzy, even though it’s focused correctly.
So, while a lens’s smallest aperture might enable you to maximise the depth of field when you’re photographing landscapes, the resolution will deteriorate.
Try shooting at f/16 instead to improve overall picture quality.
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