How do SLR photos show the illusory effect of clear background?

1. Adjust the aperture to a smaller value (such as F3.5). In this way, the background blur will be high;

2. Use a longer focal length (such as 18- 135 lens, and choose 135 end to shoot), so that the background blur is high;

3. Bring the camera closer to the subject (the photographer is close to the subject). In this way, the background blur is high.

As long as you make good use of these three points (single use and mixed use), you can shoot the blur effect you need.