If you want to get more from your DSLR cameras and take beautiful shots that will have your friends asking you for help, you need to learn about “Bokeh,” the Japanese word for photos with a nice, blurry background. The secret to leveraging your digital SLR cameras for this and other effects starts with rotating your function knob away from the AUTO setting and never looking back.
The aperture setting on your camera controls how big the aperture itself, which is the iris opening that allows in light, opens when you depress the shutter button. So it’s primary effect is helping control your shot’s exposure in conjunction with the shutter speed, and its overall brightness in conjunction with film speed as well.
But the f/ stop, the unit used to measure specific aperture opening amounts, also controls depth of field, which is the distance between the nearest and farthest object in a shoot that appear sharp, in focus. To achieve good bokeh, you need to create shallow depth of field so only your subject is in focus and everything in the background is blurry.
Fortunately, most decent DSLR cameras have the option to choose “Aperture Priority,” usually indicated on the function wheel but a capitol “A” or “AV.” This function directs your camera to set focus, shutter speed, and other settings in order to create the best shot based on the aperture setting you select.
Getting good bokeh is pretty simple at this point; the lower the aperture number the more open the iris and the more shallow the depth of field. So once you’re out shooting and ready to try, just set your aperture as low as it goes. Standard kit lenses go down to f/4.0. Then you need to set your ISO to keep your shutter speed high enough. Most decent DSLR cameras maintain image quality easily up to 800 before they start to show noise. If you see your shutter speed dropping to slower than 1/60 or 1/80, you need to increase your ISO to prevent image blur.
The last ingredient is practice. It takes some experience to figure out the right angle of light and composition to create the right portraits and still-life shots even with great use of aperture. So just spending a bunch of time with angles and then reviewing your shots can do a lot to move you from an absolute beginner to an “experienced” Bokeh beginner.
And that’s it. From absolute DSLR camera beginner to blurred background novitiate.