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Lynn Scott's
Lepidoptera Index |
Color BalanceModern digital single-lens reflex cameras from Nikon, Olympus, Pentax, Sony, and our Nikon D80 all generally include one form or another of automatic white balance or color temperature compensation. This capability corrects for the effects of excessively warm or cool lighting conditions, which can vary with the light source, making these cameras truly point-and-shoot marvels. However, under some circumstances, such as photographing moths at night, one may have a variety of light sources in use to attract the insects. Some moths are attracted to and seem prefer lighting with a modest amount of UV (ultra-violet) light while others seem to prefer incandescent lighting without the UV. This makes for a variety of color-temperature light sources in the setting for a single image. Under such combinations of lighting, the automatic white balance circuitry can be fooled, occasionally resulting in an image with a reddish, yellowish or bluish cast. To largely overcome this problem situation, we adjusted our lighting as follows:
The combination of these provides lighting that seems to provide good color results when using the Nikon D80 camera as well as the Olympus E20. Similar results can be expected when using SLRs from Sony, Canon, Olympus and Pentax. Note: We do not advocate the use of higher-wattage UV lamps such as mercury vapor or metal arc technologies for macro photography as there are real health hazards from the high-intensity UV emissions — especially skin cancer and cataracts. Getting "up close and personal" for prolonged periods with moths close to the lights means significant UV exposure for the photographer. Finally, be aware that many digital cameras' image sensors are more or less sensitive to both UV and IR (infrared). To prevent undesired photographic effects from our intentional use of UV-rich lighting, we use good quality (Hoya HMC) UV filters mounted on our lenses — they don't attenuate light in the visible spectrum and prevent undesired photographic artifacts. Similarly, if you are photographing subjects bathed in IR to keep them warm, your photos may benefit from the use of an IR-blocking filter. Filters are also inexpensive insurance to protect your expensive lenses from an errant bump or scrape. Another amazing view of nature can be had by exploiting your camera's UV and IR sensitivity — by blocking most of the visible light with suitable filters from Hoya, Tiffin, B+W, Schott or Cokin, plus a few others, and producing some amazing effects! There are some wonderful examples elsewhere on the web. Regrettably, most camera manufacturers don't include a spectral sensitivity curve for their cameras and lenses — so perhaps a test is in order. |
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