When shooting Landscape, or anything else for that matter, you usually want what you have in focus to be sharp. That's why people spend thousands of dollars on quality lenses rather than using some plastic kit lens.
I find it very common when talking to people on my Photo Workshops that they often confuse sharpness with Focus. You see, even if something is in focus it isn´t necessarily sharp and by using your equipment wrong you will actually start to lose the sharpness you paid all the money for!
Here I explain how you can achieve maximum sharpness with your lens, and what to avoid. I explain what Diffraction is and how to get rid of it.
Getting better photos is not about getting better stuff, it's about learning your craft and here is one piece in the puzzle.