Landscape = f/large
Details = f/small
I do lots of experiment with the aperture when it comes to taking landscape pictures. For an amateur photographer like me, it can be hard to tell the difference whether the picture was taken with large or small aperture. But here are a couple of examples why aperture may matter.
|f/18, 1/25, ISO 400|
|f/4.5, 1/320, ISO 400|
Noticed how the f/4.5 picture looks more "washed-out" than the first one? Also the color and details on the rocks are more distinct on the first picture.
|f/5, 1/800, ISO 400|
|f/22, 1/40, ISO 400|
On the other hand, with f/small, the larger lens opening = more light enters in. In this situation f/5 allowed more light and hence made the picture look brighter than f/22. A small aperture (f/large) is more ideal for sunny days. Again, photography is a balance. Keeping up with all the photography terminology is already hard, needless to say remembering what number to use and when to use. So back to my old saying, practice, practice, practice!