The overall power of a strobe is offered as watts per second (Ws, also known as a joule), with 1000 Ws and above largely aimed at more professional use, while 300 Ws or above provides enough light output for most basic photography needs. This is a general measure, however, and light output can change even between each burst of light, so keep this number in mind only as a general estimate.
A studio monolight will provide a lot more output than camera flashes, as well as faster bursts of light for higher sync speeds. When used with a power pack, monolights can be taken out on the road, and top-of-the-line power packs even will allow you to control attached lights directly from the power pack without making changes to lights individually, which can save a lot of time and won’t slow down the creative flow while shooting."
Though most models include a continuous modeling light, the downside to working with monolights and strobes is that the effects won’t be seen until the image has been taken. With exposure histograms and instant LCD previews, this isn’t the problem it was in the days of film, and most practiced photographers will develop a sense of what changes will look like without needing to see the image anyway. For photographers who aren’t interested in working with video, strobes are also much more affordable (and more powerful) than the relatively new technology of LEDs.
DYNALITE UNI400JRG MONOLIGHT
400 Ws | 3.6 pounds | 1/675 second (full power) | 1.5- to 4.0-seconds recycling (AC power vs. Jackrabbitpack II)
With a flash consistency of a 1/10 ƒ-stop between bursts, the Uni400JRg with a seven-inch reflector provides up to 150 full-power bursts when used with the optional Jackrabbitpack II nickel metal-hydride battery. The light provides a four ƒ-stop power range with full, 1/2, 1/4 and 1/8 power settings. The range is adjustable in 1/3-stop steps, and a maximum sync speed of 1/2200-second is available when using 1/8 power. The incredibly portable Jackrabbitpack II has very compact dimensions of only 5.0×2.0x3.5 inches and weighs only 2.3 pounds. It includes a multivoltage charger (120-240V) that will restore the unit to full charge in three hours. It also offers dual flash outlets for powering Canon, Metz, Minolta, Nikon, Sunpak and Vivitar flashes with the separate purchase of a dedicated adapter cord, which costs around $40 street. The head and battery are also available in several kit options. Estimated Street Price: $680 (Uni400JRg Monolight); $459 (Dynalite Jackrabbitpack II).
ELINCHROM ZOOM ACTION HEAD
3000 Ws | 5 pounds | Sync speed and recycle time varies by power pack
The twin-pole Action flash tube of the Elinchrom Zoom Action offers an estimated 40% to 45% shorter duration than standard horseshoe-type bulbs. The Intelligent Flash Cooling system optimizes the burst rate by electronically controlling the temperature and fan, and the Zoom Action is capable of firing off 20 serial bursts before a cool-down session is needed. The built-in reflector produces a 90º light distribution, ideal for softbox use. There’s also a zoom function for achieving harder or softer light with a control dial located on both sides of the head. Also available from Elinchrom are the almost identical Zoom Pro, which offers a more standard, regular-use quartz lamp, and the Zoom Pro HD, for up to 50 rapid-fire shots thanks to a special "HD" heavy-duty, high-quality quartz lamp. All three lamp heads are compatible with all Elinchrom reflectors made since 1974 and all 110V or 230V EL Elinchrom power packs produced since 1981. Estimated Street Price: $799 (Zoom Pro Head); $899 (Zoom Action Head); $1,225 (Zoom Pro HD Head).