This is a blended stack of 14 photos of different focus distances to create a greater depth of field (DOF, the parts of the image that are sharp) than could normally be achieved. At 170mm focal length, f/4.5 aperture, and focused on a subject 29 feet away, the DOF is normally about 2.4 feet. By taking many photos while slowly rotating the focus ring, I stepped through the scene from the branch in the foreground to the tree in the background, and stacked the images together later. To get 23 to 39 feet completely in focus in a single shot would have required an f/32 aperture, but then my shutter speed would have been 1/10 sec and it would have been blurry without a tripod. Focus stacking is a neat trick, so long as the exposure is the same on every image and there are no moving subjects (no wind).