Hobbies And Interests
Closeup Filters
The first and most practical approach to specialized bug photography, especially for those on a budget, may be the use of closeup filters or "diopters," which are attached to the front of an existing lens, and allow the lens to focus more closely. Typically, these are purchased in groups of three or four, with each one having a slightly different "power," or focus-altering strength. A collection of closeup filters costs less than $100, so this can be a good choice for someone who photographs insects only once in a while. The quality you'll experience should be quite good, though perhaps not quite up to that required by a professional.
Extension Tubes
Another option, though a bit more costly, might be the use of "extension tubes." As the term implies, these are simple hollow tubes. They attach between the lens and the camera body to extend the distance to the image plane, which allows the camera to focus closer to an object. Theoretically there should be no degradation of the image because the tubes contain no glass. However, because so much distance is placed between the lens and the image plane, the amount of light actually falling on the sensor will significantly decrease. That in turn will cause your image to appear darker in the viewer, and you may require larger aperture settings.
Macro Lenses
If you're a dedicated insect professional, and need the finest lenses available, you'll settle on some type of "macro" lens. These are the finest, most highly-tuned and sharpest lenses in the arsenal of any lens maker. They are also the most expensive. Macro lenses have the ability to focus very closely as a normal part of their function. Where portrait photographers might have little or no use for a macro, they are the favorite of most serious "bug shooters."
Focal Length
Your final consideration may fall on "focal length." Focal length is the distance from the center of the lens to the film or digital sensor in the camera body. In effect, the greater that distance (measured in millimeters), the larger the image will appear on the film or sensor. The "longer" lenses -- the ones with the greatest focal lengths -- will allow the photographer to be farther away from the insects he photographs. Typically, they will also be heavier and more expensive.