Landscape Photography - Maximizing Depth of Field and Sharpness

[Hugh Weaver]

Maximizing depth of field and sharpness when you're shooting
landscapes is not the black art that many people seem to
think. There is a lot of confusion, misleading information and
incorrect assumptions being made on the Internet when it comes to f-
stops and focusing distance.
Common Mistakes
One common and misleading assumption is that to get maximum depth of
field you simply choose an aperture of f16 or above and focus about
one third of the way into the scene. This method may work to a degree,
but you are not getting the maximum depth of field or maximum
sharpness from your lens, particularly if you are using an ultra wide
lens in the 10 to 24mm range.
Maximizing Depth of Field
If you look at any depth of field table, which incidentally are freely
available on the Internet, you will notice that the depth of field
increases as focal length shortens, which means that a lens with a
focal length of 50mm will have less depth of field than a lens with a
focal length of 17mm at the same f-stop. I highly recommend you to
check your own focal length against these tables to get the
approximate hyperfocal distance for your lens.
For wide and ultra wide lenses you will want to set your focus point
to roughly four feet into the scene, as this is approximately where
the hyperfocal distance will be for these type of lenses. This will
mean that everything from about two feet in front of the subject to
everything behind the subject will be in sharp focus. Remember, as you
increase the focus distance you actually decrease the amount of
sharpness in front of the subject.
Maximizing Sharpness
If you want to maximize sharpness, especially if you are planning on
doing large prints then you need to ensure that you are using
appropriate apertures. A common misconception is that setting the
aperture to f22 will make everything sharp. Not true! All lenses, even
the most expensive pro models suffer from diffraction. It has nothing
to do with build quality but rather the law of physics! Diffracted
light is light that is reflected off the edge of the aperture blades.
At large apertures it is not a problem but at small apertures the
amount of diffracted light increases to the point of affecting image
sharpness quite noticeably. Therefore I would not recommend using
anything beyond f16.
If you are doing very large prints at A2 and above then I would not
recommend using even f16 but instead using f11. Obviously if you do
use f11 you will not get the same range of depth of field  as you
would with f16 but what you can do in this instance is take two
exposures. Take one exposure at the hyperfocal distance then take
another at infinity. This will ensure you have maximum sharpness
across the two. You can then blend them both together in Photoshop for
a super sharp image.