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Lynn Scott's
Lepidoptera Index |
Optimizing Camera Settings for Macro PhotographyAchieving optimal camera settings for macro or close-up photography is a matter of physics, regardless of the kind of camera being used. A few key concepts are crucial:
In other words, things that are very close to the camera are harder to keep in focus than more distant objects, particularly if they move around. The depth of field increases as the aperture (or iris) of the lens is made a smaller diameter (that is, the camera is set for a numerically larger f/ value). As the aperture is made smaller, however, the exposure time must be increased to compensate for the reduced amount of light reaching the image sensor in a given amount of time. For moving objects (even slightly moving objects) the longer exposure time can result in blurring, but using the electronic flash with its extremely short flash duration will mitigate the blurring problem for macro photography of live subjects. Aperture priority is the preferred close-up photographic technique for achieving best image sharpness. This forces the camera always to use the specified aperture setting, say f/16, and to vary other settings to achieve the correct exposure. A modern digital camera can be programmed to automatically adjust these other settings, including one or more of:
As might be expected, there is a complementary shutter priority camera setting that is most often used for sporting events or other high-speed activities. The camera can be set to use a certain shutter speed (like 1/1000th of a second) to give the effect of stopping the motion, and the camera then achieves the correct exposure by one or more of:
For purposes of macro photography, shutter priority should generally be avoided. Although the camera can be programmed to alter the ISO setting automatically when in aperture or shutter priority mode, it is generally better to leave ISO at its lowest fixed value. Increasing the ISO setting can impart noise, or apparent graininess, to the image, especially under low-light conditions. The depth of field needed for acceptable picture focus, especially with a three-dimensional object, will be minimized when the camera and subject are positioned so that the subject and the image sensor (back of the camera) are parallel to each other. This is not always possible in close-up photography of small objects, and our experience has been that small objects shot from an angle may not be entirely in focus. Some cameras, including the Nikon D80, include an optical depth of field preview button that physically stops down the lens to the selected f/ stop setting, showing the actual subject focus in the viewfinder. For active subjects such as live moths, however, its use is rather impractical. |
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