Saturday, May 28, 2011

Up Close and Personal, Part 1

Life-size. 1:1 magnification. In other words, when the image projected on the sensor is the actual size (or larger) of the subject being photographed, you're about to discover a whole new visual world -- the art of macro photography.

You wouldn't know it by the weather (at least here in Oregon!) but it's spring and that's the perfect time to journey outdoors to photograph the explosion of life around us. And there's no better way to do just that but Up Close and Personal! The least expensive and most effective method to get started is with extension tubes.

Extension tubes are hollow metal or plastic spacers that simply increase the distance between your lens and the camera sensor which increases magnification. They're available in varying lengths (e.g., 12mm, 20mm, 36mm) and can be used individually or stacked together to further increase a len's magnification (i.e., the more extension, the greater the magnification). Extension tubes house no glass so there's no optical degradation and most are made with the electronic couplings required to maintain TTL functions between your body and lens. A handy formula to remember is if the extension is equal to the lens focal length, then you will get true life-size magnification.

In macro photography with extension tubes, the further the lens is moved from the sensor: the closer the focusing distance; the greater the magnification; and the greater the loss of light. Moving the aperture further from the sensor results in the inverse-square law of light falloff and a fainter image without exposure compensation (e.g., when shooting life-size, you lose 2 full stops of light!). Moreover, depth of field is miniscule, even stopped down at apertures like f16, so longer exposure times are necessary. (Note: specific techniques involving extension tubes in macro photography will be addressed in next month's post).

Considering the challenges macro photography presents to a beginner, I decided the Keizer Iris Festival with its rainbow of plants was the ideal place to take my Chemeketa Community College Nature Photography class for their first attempt at close-up work. Their assignment was to de-contextualize a flower - take it out of its context - or to investigate the art, pure form, and elements of design it displayed. These images were my examples for the class to review. Next month, we'll take a look at the animal kingdom . . . Up Close and Personal, too!