Finally, the maximum aperture of your lens plays a big role in macro work. Creatively, a large maximum aperture allows you to limit depth of field for soft backgrounds that accentuate your subject. It also gives you the most latitude working with natural light and getting the fastest shutter speed possible when photographing moving subjects like insects.
Ring lights are a popular solution for macro photography because they provide very even lighting for objects close to the lens.
For portable outdoor use, consider a battery-powered ring flash like the Sigma EM-140, which is available in five variations to provide TTL metering for Canon, Nikon, Pentax, Sigma and Sony DSLR systems. Estimated Street Price: $379.
Or, if you already have a compatible Canon or Nikon speedlight, you might opt for the Ray Flash from ExpoImaging, which will convert your existing flash to work as a ring light. Estimated Street Price: $199.
A studio ring flash offers some advantages over portable units. Their larger light sources provide softer, less focused light. And because they're more powerful than smaller portable units, they will provide better illumination if you're working farther from your subject with a longer focal-length macro lens. If you're working indoors, consider using a studio ring flash like the AlienBees ABR800, which has a 6-stop adjustable output. Estimated Street Price: $399.