What Is Important Here?

I think this photo nicely illustrates the idea I want to highlight in this post.

Focus of interest.

There are a number of techniques that can be used to concentrate interest and attention on certain aspects in a picture. Many of them are well known such as compositional techniques like placing items on the intersections of "thirds". Leading lines can be employed and, of course, we are always somewhat drawn to what is in the centre of the frame. Focus, however, can also be a powerful tool for channeling the viewer's attention.

Here the plane of focus has highlighted the rag, the bolt, the writing on the door and the pattern in the footplate. All of these were in focus at once because the plane of focus and the plane of the side of the digger intersect at a diagonal from this viewpoint.

Keep this tool in mind.