Problems with using small aperture settings
Using a smaller aperture means that less light can pass through the lens and a longer exposure is required. This can introduce blur if the subject moves during the exposure.
If there’s not enough light you can create some by turning on a lamp, using a studio light, turning on your flashgun or activating your camera’s pop-up flash.
Alternatively, use a higher sensitivity (ISO) setting. Some photographers worry that using high sensitivity settings will mean that they produce noisy images, but modern digital cameras produce remarkably clean images at settings we would have only dreamed about a few years ago.
Any involuntary movement of the camera during an exposure will introduce blur and the longer the exposure the more likely you are to move the camera when it is handheld.
Although you can use a higher sensitivity setting to allow a faster shutter speed if your subject in stationary you don’t need a short exposure to freeze its movement and a better solution that enables you to produce the highest quality result is to support the camera on a tripod so it is rock-steady.
For the best results you should use a remote release or the camera’s self timer to avoid introducing any wobble by pressing the shutter release.
In addition, SLR users should consider using the mirror lock-up facility. This turns shooting into a two step process.
The first press of the remote shutter release triggers the mirror to lift (the viewfinder will go black), while the second, which is made after you are sure any vibrations caused by the the mirror lifting have died, trips the shutter.
As compact system cameras (CSCs) don’t have a mirror, CSC users don’t need to worry about mirror lock-up!
Although using a small aperture ensures that there’s lots of depth of field, if you don’t use it properly you can still wind up with a soft foreground.
As depth of field extends twice as far behind the focus point as it does in front, if you focus on the horizon or towards the farthest point of the scene, much of the depth of field is wasted.
Instead you need to focus towards the front of the scene so that more of it is within the sharp zone created by the lens’ depth of field.
Hyperfocal distance focusing is usually mentioned at this point, but using it requires using tables or a lens depth of field scale.
Rather than getting bogged down with this, a far better rule of thumb is to focus about one third of the way into the scene.
Although using a small aperture setting results in lots of depth of field, another rule of physics means that the sharpest part of the image isn’t as sharp as in an image taken using a slightly wider aperture.
This is because of something called diffraction, the impact of which becomes more noticeable as the aperture is closed down. Put simply, diffraction is the bending of light rays as they pass by the edge of the aperture.
Using a smaller aperture means that a greater proportion of the light waves are bent and as a result the image is softened more significantly.
The only way to avoid diffraction from spoiling your images is to use a larger aperture, even one stop may be enough.
So next time you are shooting a landscape, don’t set the smallest aperture possible, open up a stop or so.
And for the best results, use a mid-range aperture setting and focus stack as described earlier.
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