If you are really serious about close-up photography, and really want to take creative control, invest in a ring light, sometimes called a ring flash. A ring light fits on a macro lens and can provide ratio (1:1, 1:2, etc.) as well as shadowless lighting. You control the light by turning on and off, and by adjusting, the power output of the two flash tubes that circle the lens.
In addition, you can use the ring light’s Flash Exposure control, the +/- settings, to fine-tune your exposure, and to take a daylight fill-in flash picture.
The light from a ring light also adds contrast to a picture, making it look sharper than a natural light photograph. I used a Canon Marco Right Light MR-14EX on my 50mm macro lens for this close-up picture of red-eye tree frog,
You cannot use a ring light on a wide-angle lens. If you do, you’ll get a hot spot in the center of the frame.
Ring lights are wonderful accessories for close-up photography. There is, however, one problem when using them when photographing reflective objects, such as the eyes of the red-eye tree frog. As you can see in the bottom image (cropped from the original top image), the reflections of the flash tubes show up in the animal’s eyes. There is no way around that when taking this type of picture.
Therefore, you need to clone out the reflections in the digital darkroom. For best results, zoom in on the photo on your monitor so that the eyes (in a case like this) almost fill the monitor. Then select a small, soft-edge brush and carefully clone out the reflections. As is most often the case, the smaller the brush size the better.