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| Pine Needles and Dew |
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.
A lens with bad bokeh does not have smooth gradations between colors/edges in the out-of-focus areas, it looks choppy, with sharp edges instead of smooth edged blurs. Bad bokeh can also be noticed in specular reflections or points of light. With bad bokeh these will again look choppy or ballon out too much and draw the eye away from where you want to focus. Click here for an example of really bad bokeh.
When investing in a macro lens, pay particular attention to its bokeh. Search the web for examples of shots made with this lens and study its bokeh.
The lens I used in this photo is a Tokina 90mm Macro. I had narrowed my choice between this lens and the Nikon 100mm Micro (Nikon calls macro micro for some reason.)
The price was close enough that it didn't matter. The Nikon has a better build quality and is more rugged. But the purpose of a lens is to render the photograph the way you want it. My choice of the Tokina was based on my judgement that its bokeh was better.
Your choice may have been different; at the high end of quality lenses, good bokeh and better bokeh can be quite subjective.
