Find a subject in front of a background with depth. Take a close viewpoint and zoom in; you’ll need to be aware of the minimum focusing distance of your lens. Focus on the subject and take a single shot. Then, without changing the focal length, set the focus to infinity and take a second shot.
The closer you are to the subject, the shallower depth of field; the further from the subject, the deeper the depth of field. That’s why macro shots taken from very close viewpoints have extremely shallow depth of field, and if you set the focus at infinity everything beyond a certain distance will be in focus.
As you review the two shots, how does the point of focus structure the composition? With a shallow depth of field the point of focus naturally draws the eye, which goes first to the subject that is sharp. It generally feels more comfortable if the point of focus is in the foreground, although there is nothing wrong with placing the point of focus in the background.
Your eye is naturally drawn to the sharpest part of the image, however adding the out of focus element to the frame can give a feel of voyeurism to some of the images, it seems to place you in the image. The first two images are interesting as they have created a frame so although the focal point / sharpness is different they feel equally as strong. The middle image is the least interesting as the rose is centred to the frame therefore the only successful picture is when the rose is in focus. In the last two images the out of focus flowers are to the corner of the frame and all four images could be successful depending on the assignment they would be attributed too. They have a strong sense of voyeurism and being part of the frame.