I’ve had a lot of questions over the last couple of months regarding the “best” aperture to use for scenics and landscapes. Tradition holds that you should use the smallest lens aperture for your scenic and landscape photos. The purpose of using small apertures like f/22 is to maximize your depth. In other words, you want everything from the foreground to the background to appear in sharp focus.
However, there is one important thing to remember about your lens. They are sharpest (i.e. resolve the most information) between an aperture of about f/8 to f/11. When you use smaller apertures such as f/22 or f/32, then the image quality of your lens tends to degrade ever so slightly due to light diffraction. It isn’t a huge amount of degradation, but sometimes it can be enough to make you think twice.
So, what’s a photographer who wants the highest image quality to do? Some photographers say that the depth of field you lose at f/11 is not such a big deal because the sharpness you lose from diffraction at f/22 is worse. My recommendation and my general practice is to shoot landscapes between f/11 and f/16 as a way to get the best of both worlds. Good depth of field with minimal diffraction.
However, try experimenting with other apertures as well. For every rule, there is a photo that shows how/why it can be broken. Take the above photo for example. I shot it at f2.8 with the purpose of bringing more attention to the small foot bridge in the foreground. Although the “best” or “sharpest” image would have been made at f/11 – f/16, I think f2.8 brings a different dimension to the image.