In photography, bokeh is an aesthetic quality of a blurred out-of-focused portion of an image. In photographic terms, bokeh is described as “how the camera renders out-of-focus areas”. Focalization is the process of selecting a focal point and, usually, a wide-angle lens, in order to capture a certain area. Distortion caused by lens distortion is corrected by using the right lens.
The main reason behind bokeh is that the images captured with a wide angle lens tend to have higher contrast, because the focal length is longer than the focal length of shorter lenses. In photographic terms, bokeh is “how the camera renders out-of-focus areas”. Focal curves specify how the lens varies its field of view depending on the selected apertures. Distortion caused by lens distortion and aberration is called bokeh.
The term “bokeh” (in Japanese) means blurred out in pictures. To some extent, this describes out-of-focal view in landscape and portrait photography. The Japanese perceive bokeh as an important aspect of fine art photography. Some Japanese photographers use bokeh to emphasize a subject’s silhouette or to soften a harsh edge. In photography, bokeh (sometimes also referred to as “lens noise”) is what causes the out-of-focused background in your photo to appear blurry bokeh.
In general, when taking photographs with a wide-angle lens, it is better to use a smaller aperture. This holds true even if you are using a relatively flat plane. That said, there is no reason why you cannot use a larger aperture with your wide Angle lens, and sometimes it can be desirable to use a smaller one for portraits because it creates a soft effect out of the focal point. Your personal taste may dictate whether or not you prefer a small aperture priority mode with your digital camera, so experiment to see what suits your situation best.
One of the reasons that bokeh can become noticeable is when you are photographing a subject that is at an angle that causes the depth of field to be extremely shallow. The depth of field happens when the foreground is the entire subject, but the middle is blurred because of the position of the camera lens. For instance, if the subject is in the foreground and the focus is on the center of the frame, the depth of field will be severe because the center is already in focus, and the out of focus background will be completely out of focus. Even though it is easy to notice when you are photographing with a fast lens, it is very difficult to correct for this situation when using a lens of a different focal length. Because of this, it is important that you are aware of and understand bokeh when you are preparing to take photographs of people with a wide angle lens.
It is also very easy to develop bokeh problems with your camera when the lenses are not well set up. Focal length, aperture, and lighting can cause the bokeh to appear out of focus when the photographer is trying to capture a specific area of the background. The best way to avoid this situation is to prepare each lens before you leave the studio, and practice a great deal before taking the photos. Make sure that the aperture settings on both lenses are the same, and that there is plenty of light on the subject so that they do not get underexposed when you are photographing the background.
Most photographers do not realize that there exists a much simpler way to avoid bokeh issues with digital SLR cameras. It is called for focus stacking and it is extremely easy to execute. Instead of focusing on one particular area like most people do when taking portraits, why not stack your focal length lenses on top of each other? By doing this, you will have two equally powerful and focal points. This method can be easily executed when shooting portraits in portrait mode, or outdoors.
The key to perfect bokeh in portraits is in focusing on your subject and not on the background. Focus on the subject so that the background is out of focus and blurry. If you are in portrait mode, simply switch off the image sensor and take the photo as normal. Once you have the focus set just right, then bring the focus back in and notice how much more blurring the background has. By doing this over, you will find that you are getting a nice blurred background, but no out of focus areas, just like when using wide aperture photography.