Sunday, March 23, 2008

Life is a blur

It’s funny how you can go about your job and take simple things for granted. In photography one of the key elements is focus. I know it is important but what I overlook and took for granted is the part of the picture that is out of focus, that everyday blur in an image.

I was reading David Busch’s book “Canon Eos 40D Guide to Digital Photography” when I stumbled across a few interesting entries. While most of the book is describing the various features and multiple menus the cameras has to offer it also gave some general descriptions of photography and lenses. Among those descriptions were two photography properties I never heard of but use every day when I take pictures: Bokeh and circles of confusion. What are they? Simply put they are blurring.

Blur, or more aptly put the out of focus areas of an image has a technical name, bokeh. It’s not the blur of two slow of a shutter speed to freeze the action but the areas of a image that are rendered out of focus, either partially or completely. As photographers we can use selective focus to improve the composition of a photo by decreasing the amount of image area in sharp detail to make a part of the image standout or emphasize a portion of the image to the reader. For example I used selective focus to emphasize the pitcher facing off against the batter at the plate at the picture at top.

Different focal length lens produce different amounts of depth of field, the amount of area that looks in sharp focus. Generally the longer the focal length of the lens and the wider open the aperture the less depth of filed and the more bokeh an image will have.

While you might think a circle of confusion might describe my life at work these days it is the description of the focusing point of a ray of light. When a point of light is out of focus its edges become indistinct and soft. When the point of light becomes large enough our eyes see a disk of light with no sharp and distinct edges.

Lots of things affect the shape of these circles of confusion from the type of glass used in the camera lens element to the styles of blades used to build the lens aperture. These disks can be either pleasing patterns of light in an out of focus background or distracting globs of light.

It was odd that after almost 30 years of picture taking dating back to my high school days I discover a name for some of the basic elements of photography. It just proves that it is never too late to learn something new


Safari Mom said...

Wow that is a great blog and a fantastic way to explain some Tecky terms in Photography. Always enjoy your shots.

Anonymous said...

Yep, I think I pretty much understood all of it this time ;) Lovely illustrations, by the way.