Landscape Photography Mistake No. 10: Soft details
Although using a small aperture increases depth of field, the zone of acceptable sharpness within an image, it also increases the impact of diffraction, the bending of light as it passes over the aperture blades.
Bending the light means that it isn’t focused on the sensor and consequently the image is softened.
The smaller the aperture, the greater the proportion of bent light rays and the softer the image, so that even the point of focus is softer than it is at a larger aperture.
The worst effects of diffraction can be avoided by using an aperture setting that’s a stop or two larger than the minimum value available.
However, it’s worth experimenting with your lens to find out what its optimum aperture is.
This can be done by shooting a series of images of the same subject taking shots at every aperture setting.
Then, check the sharpness of the focus point in each image to can find the sharpest one which was taken at your lens’s optimum aperture.
Focus stacking allows you to use your lenses optimum aperture and still create an image that is sharp from front to back.
All you need to do this shoot a sequence of images at the optimum aperture, but with the focus set to a different distance in each.
Start with the focus on the near foreground and gradually adjust the focus for each shot until you take one with the focus on the horizon.
It’s essential that the camera doesn’t move while the sequence is shot, so use a solid tripod.
The last stage is to merge the images, fortunately this can then be done automatically using Photoshop’s Photo Merge tools.