Selective Focus and Bokeh

Pine Needles and Dew

For macro photographers, these two concepts are very important.

Selective Focus
The use of limited depth of field to focus sharply on a specific object in the scene – while other parts are clearly out-of-focus – is called selective focus.

In macro photography, depth of field (or focus) is often quite small due to the closeness of the lens to the subject. Then, selective focus becomes a necessity, and selecting where to focus is your key decision.

In the pine needle photo, I picked two dew drops that acted as lenses to bring other pine needles into focus (click on the pic to see it larger).

Bokeh
The out-of-focus parts of the subject are, for me, what makes this photo interesting. At the least, the quality of the out-of-focus parts are critical to this shot. The way a lens renders out-of-focus areas is called its bokeh (pronounced bow-kay), from the Japanese word for blur or haze.

Multiple Exposure

Click to enlarge.

My Nikon DSLR and many other cameras offer an in-camera method of making multiple exposures. You set the number of shots and your meter calculates the exposure such that you won't overexpose. Without this feature - and in the old film days - you would need to underexpose each shot so that the combination resulted in a proper exposure.

This shot is War Eagle Mill in Rogers, Arkansas. While making the multiple exposures, I panned with the water wheel, attempting to freeze it enough to be a recognizable subject while letting the side walls blur and the water do whatever it did.

Multiple exposures are used most often for an expressionistic look. Try moving your camera in the direction of the pattern (for example, vertically with a tree trunk). A little goes a long way, so at first try smaller movements in between shots.

Photographing The Moon

At the last class, several of you were asking about photographing the moon. Good timing, since we are right at Full Moon Aug. 1st. (While you are out, notice how much light is present and attempt a few shots of earthly objects. You can even try the "ghost" image shot we discussed or some light painting)
Basics to remember:

• To fill the frame with the moon you will need a very long telephoto lens 600mm +. But it is still worth trying a moon shot for inclusion in other types of shots. (See Ansel Adams' Moonrise, Hernandez, New Mexico, 1941)
• The moon is very bright. Some suggest the "sunny 16" rule for exposure: f/16 at same shutter speed as ISO. Example: ISO = 100 f stop = f/16 Shutter speed =100. There is a "loony 11" rule which uses the same idea but at f/11.
• Keep in mind that atmospheric conditions can make a difference so exposure is something of a trial & error effort. Check and see if your camera will automatically bracket exposure re. - take one normal and one over and one under exposed. if not this is a good time to practice doing this manually as it can be used for most all of your photography.
• Stability is important so use a tripod and hopefully a remote release - and since the moon is moving, OK the earth, check your framing.