I'm really into landscape photography but I can't get my pictures to look sharp. They look boring and dull. I focused to infinity by using the infinity symbol on my lens and by manually focusing using an app which calculates the DOF. According to the app if I set my aperture to f/5.6 and zoom all the way out to 10mm, I should have a DOF of infinity when focusing on something that is 3m away. I tried different apertures but the higher I go the blurrier it gets. Is the lens just not good? I saw some reviews and they weren't as good as I was hoping. They all found that the lens is not sharp and when looking at example pictures on Google that were taken with the same lens, they all look unsharp. Should I get a different lens or am I doing something wrong?
EDIT: Before I asked this question, I already did all the things mentioned in the question, http://photo.stackexchange.com/questions/50006/why-are-my-photos-not-crisp
I tried manually focusing at the furthest subject to really make sure it's within infinity and it's still not sharp. Even if I take a picture of a subject that is just a few cm away, and focus so that it looks crisp in the display, it doesn't turn out crisp on the computer. I can see a difference between f/5.6 and f/3.5 in sharpness but if that is the best I can get out of that lens I'll be very disappointed.
Here is one picture I took of the field next to our house. I took it when I got home. I increased the exposure a little with camera raw. It looked really bright on the camera display but on the computer it was underexposed. I focused to infinity and put it on a tripod and set up auto shutter release. This is the terrible outcome:
For example, this picture here was taken with the kit lens before I started getting into photography, meaning before I knew anything about aperture, DOF, etc. and it's really sharp compared to the 'better' new lens. So I must be doing something wrong with the new lens because the old picture shows that I'm able of taken sharper pictures. Generally, all I the pictures I took with the kit lens are way sharper.