Modeling Light Power. Modeling lights give you a good idea of how the light will fall on your subject. A lot of photographers have come to rely on modeling lights because they make the process of lighting close to WYSIWYG. With AC-powered flash units, modeling lights aren't a big problem. But with battery-powered units, they add significantly to the power drain. Therefore, one needs to be more judicious with the modeling light and be aware that, in some cases, battery-powered monolights don't call for modeling light usage at all.
Light Modifiers. One of the big advantages of studio-type flash is the range of excellent light modifiers available—parabolic reflectors, umbrellas, light boxes, snoots, grids, beauty dishes, barn doors and more. Many units accept standard "S" modifiers. This is one of the most important advantages monolights have over smaller, hot-shoe-type flashes. Although the overall power output is less than a studio strobe pack and head outfit, you can use most, if not all, of the same modifiers. Check to see what's offered for each unit you're considering to make sure what you need is available.
Size. Portable means you're going to be carrying it so consider dimensions and weight. Battery-powered monolights are more portable than studio strobe packs and heads, and they're more bulky than shoe-mount flash units. Everything in life is a trade-off, and when it comes to portablility, monolights aren't perfect, but the trade-off is attractive for many location photographers, in particular.
Price. Higher-end monolights generally cost more than shoe-mount flash units, low-end monolights less than high-end shoe-mount units. You have to weigh the benefits versus the cost, as with everything in photography. Monolights can do things shoe-mount flash can't; if you need those features, you need a monolight.
ProfotoProfoto's battery-powered monolight is the B1 500 AirTTL, a self-contained cordless model with an onboard, exchangeable, integrated, lithium-ion battery, so you don't have two pieces to deal with. The unit also offers TTL exposure control with Canon DSLRs (Nikon compatibility is expected in 2014). Just plug the Air Remote TTL unit to your camera's hot-shoe, and the off-camera B1 unit will automatically adjust its output for correct exposure. Power can be adjusted from 2 to 500 W-s in 1/10-stop increments (a nine-stop range), recycling times range from 0.1 to 1.9 seconds (the unit can fire up to 20 bursts per second at lower power settings), and durations can be as brief as 1/19,000 in Freeze mode.
Powerpack & Lighthead Options
|While this article has focused on the benefits of monolights that can use a battery pack or plug into the wall, there are also battery-powered studio strobe-type units available. These tend to be very powerful and give you maximum flexibility/control and all of the advantages of a large studio system. On the downside, these systems are heavy, bulky and costly. If you need maximum power and you need it without being connected to an AC outlet or a portable generator, a battery-powered studio strobe pack and heads is the answer. In this category are such systems as the Broncolor Move 1200, Elinchrom Ranger RX, RX Speed AS and Quadra RX, Hensel Porty L and Premium Plus, Paul C. Buff Zeus, and Profoto Acute B2, Pro-B3 AirS and Pro-B4.|