Photography is a two-dimensional platform where photograph itself is a flat piece of paper, or in this age, an image on a screen.
Although, most of us would not be able to see a piece of photograph as such, we still perceive depths within the photograph. To put it bluntly, it is actually our brain that was fooled and learned to believe that there is depth! (unnecessary exclamation mark that just wants to capture your attention further)
Photograph has certain “visual cues” that photographers use to create ‘depth and perception’. One of them is a “Depth of Field” effect.
You may have come across photos that has a blurred backgrounds, sometimes the foregrounds while the subject remains focused like the photo above, this is a “Shallow/Narrow Depth of Field”. The blurred backgrounds and foregrounds create the illusion that there is depth between the subject in focus against its backgrounds and sometimes the foregrounds.
To achieve this effect, the photographer will need to set the aperture or the f-stops of his lens to the smallest possible number. This will change the size of lens aperture diaphragm to the widest possible.
One main caution with this setting is that your point of focus is quite narrow and even extremely narrow when your aperture is f1.8 or less. If there is movement in your subject or your camera handling is not steady or the shutter speed is not fast enough, chances are that your focus is off pretty easily. My advice, is to try to find a strong surface to lean on or use a tripod to help steady your camera while taking the shot.
