TO BE WRITTEN
The large electronic flash units that are designed for use in photographic studios can be very useful for both close-up and macro photography. They provide plenty of power, and so still provide lots of light even when bounced from an umbrella or directed through a large diffuser to prevent dark shadows. The better units have variable power, either at fixed intervals or continuous, from full power to 1/16th or even less, allowing you to choose from several apertures. Variable power also allows you to use small apertures over a range of magnifications.