The V600-D is the perfect match for demanding professional wedding/portrait photography and has the power for many commercial photography projects, too. With the variable power control, a typical f-stop can be adjusted from 5.6.5 to 22.2, with a standard head ten feet from the subject. Since professional photographers love 2103-FC bare tube heads, with their 250 watt modeling lamps. The V600D is designed to handle a full 1000 watts with its own breaker. This pack is compatible with most of the low sync voltage digital cameras.