Use a Flash in Digital Macro Photography
The battery-operated flash is an ideal artificial light source for macro and close-up photography because it’s lightweight, small, and lets you control how much light it emits.
In some cases, without using artificial light, you just don’t have enough light in your scene to accommodate the aperture and shutter speed settings of your choice without resorting to a very high ISO (and therefore a lot of digital noise).
Rather than changing your exposure settings to meet the needs of a certain scene and its level of brightness, you can select the exposure settings that work best to convey your message, and then illuminate the scene in the proper amount to work with your exposure settings.
Having control of the flash’s level of brightness is important; this feature enables you to add just enough light to a scene to manage a perfect exposure at the aperture, shutter speed, and ISO of your choice. To do this, you need to become familiar with your battery-operated flash. Refer to your owner’s manual to find out how to increase and decrease its level of brightness.
If you use a TTL sync cord (an accessory that enables your flash to automatically emit the proper amount of light based on your camera’s settings and the flash’s distance to the subject) to synchronize your camera and flash, you don’t have to set the power levels manually.
Your camera, flash, and TTL sync cord must be designed to work together. Otherwise, the flash’s ability to read the camera’s settings is disabled.
If you don’t own a TTL cord, you can synchronize the camera and flash with an ordinary sync cord, or with wireless transceivers. In this case, you’re responsible for setting the flash’s power levels manually. You can do so with a light meter by testing the output of the flash and adjusting its power to match the aperture of your choice.
If you don’t have a light meter, you can use the trial and error method to create a perfect exposure. To do so, set up your flash, sync it to the camera, take a shot, analyze the results on your camera’s LCD display, and determine whether you need to raise or lower the power of your flash. Repeat this process until you get the results you prefer.
Your aperture (and not your shutter speed) determines the effect a flash has in an image. A larger aperture lets in more light and requires a less intense flash than a smaller aperture. After using your equipment a few times you should become familiar with which flash settings work best for a particular aperture setting.