A monolight (a.k.a. monobloc to our European friends) is a self-contained studio flash, typically but not always powered by an AC power source, which allows the fitting of light modification attachments, such as umbrellas. It consists of a power source and a light head, all contained within a single, compact housing.
Monolights usually have variable output settings for full, half, quarter power; some go down to 1/32 power. One of a monolight's most valuable features is a modeling light that allows you to preview the effect of the flash and whose output can be varied to match the flash setting output.
Monolights have input for a PC (Prontor-Computer, not a computer) cable, allowing it to be directly triggered when connected to your camera's corresponding PC outlet. Alas, not all digital SLRs have a PC connection (especially starter DSLRs), and so most monolights also have an optical "slave," which can be set to trip the flash when it sees another flash go off.
These days, radio-controlled slaves are a popular option that allows a monolight to be wirelessly triggered without a flash or cable.
Adorama's Flashpoint II 320M is a 150 Wat Second monolight that, at $100, easily fits within the budget of photographers who need lighting equipment for a home studio or location shooting. The reflector is metal and can handle umbrellas with poles that have diameters of 8-10mm; this is a good fit for 32 to 45-inch umbrellas.
Most times, power for a monolight is provided by AC current. You can plug it into a wall and start shooting! But there are times when you're out in a field or on location where an AC outlet may not be so conveniently located. There's a whole new breed of monolights that offer a DC option that connect to battery power packs available from the monolight manufacturer, or third parties such as Quantum Instruments.
Photogenic's battery-powered AKC160B StudioMax III "B" units (right) work on either AC power, Photogenic's AKB-1 battery, or by models from other manufacturers. A fully charged battery pack will provide 200 full-power flashes. When the lights are DC-powered, the modeling light circuit is disabled to conserve battery energy.
Power to the Monolight
To understand monolights and studio lighting hardware in general, you'll need to learn a new set of photographic buzzwords.
Let's start with the most important: Output power is measured in Watt-Seconds (WS). Watt Seconds are simply a measurement of the power and discharge capacity of an electronic flash's power supply measure of an electronic flash unit's power (think automobile horsepower) but does not indicate the total amount of light that can be produced by a given electronic flash unit.
Some monolights include a rating for a Guide Number (GN), which is a number that relates the output of flash. Guide Numbers are quoted in feet or meters (depending on where you live in the world) and are valid for a specific ISO speed. The higher the guide number, the greater the light output. Guide numbers serve as a way to calculate aperture when shooting flash in manual exposure mode. To determine the correct aperture, you divide the guide number by the distance of the flash--not the camera--to the subject.
Other important considerations when evaluating different monolights are flash duration and recycle time. Flash Duration is exactly what it sounds like and is the amount of time elapsed after triggering the electronic flash tube in the flash head. It is usually short--it's measured in fractions of a second. Recycle Time is the time it takes after the electronic flash has fired until the monolight is fully charged and able to deliver another full amount of light. This can be a big variable and can be a determining factor in selecting one monolight over another. Until the flash has recycles, you have to wait.
> Can you make a portrait with just one monolight? You sure can, as I did with this portrait of my wife, Mary, which was made with a single FlashPoint II monolight placed at camera right. Some of the shadows on the other side were filled with a Flashpoint 5-in-1 Collapsible Disc Reflector. Camera was a Canon EOS 20D with Canon 85mm f/1.4 lens. Exposure was 1/60 sec at f/18 in Manual mode and ISO 100.
A Monolight Shopping List
Here are a few things to keep in mind when considering a monolight. As in all photography, this involves a series of trade-offs between functionality, ease-of-use, and cost. You'll need to carefully juggle your budget with your want list.
Continuously variable output: Most monolights have individual power settings of 1/4, 1/2, 3/4, and full, which is good because sometimes when working with a single-portrait subject you don't want to blast them with enough light for an exposure of f/64...but sometimes you need more control. Continuously variable output allows you to fine-tune the exposure to get precisely the aperture and depth-of-field that you want.
The Flashpoint II Monolights, such as the Model 1220A
Proportional modeling light: Less expensive monolights simply provide an on-off modeling light to give you some idea of what the final lighting effect will be. Those with proportional settings allow the modeling light to vary with flash output.
Keep in mind that although the modeling light may be bright it is not as bright as the flash and when you set a low power setting the effect of the modeling light may be difficult to see if the ambient light is high. So, when possible, dim ambient light while working with modeling lights.
The Norman ML-600 600 Watt Second Monolight ($636.95, right) has a 250-watt modeling lamp with Full, (Proportional) Ratio and Off settings. (It's also available with a built-in radio slave for approx. $860.95.)
Fan cooling: Placing the modeling light, power supply, and flash tube (that's the glass tube that produces the flash from a capacitor filled with energy from the power supply) inside a single housing creates heat. A fan-cooled monolight is better than an air-cooled model but will make the monolight bigger, heavier, noisier, and more expensive. Is it worth it? That's up to you and your bank account.
Portability: To many photographers the ability to have the power supply and light head in a single package makes for simple set up and greater portability. That's why lots of companies offer packages consisting of monolights, umbrellas, light stands, and even a case for a single ready-to-go package.
Light modifiers: Raw light from monolights is seldom useable as-is. To make a portrait or shoot a product, you're going to have to modify the quality of that light. Does the monolight have a shaft to allow attachment of an umbrella? If so what size is it? Umbrellas come in various sizes with the shafts of European models different than others. What about attachments such as reflectors, light banks, or accessories such as snoots? Are any available or will third-party accessories fit?
The entire Bowens monolight system, is compatible with one of the worlds most diverse selections of reflector (S-Type Bayonet) systems and light control accessories.
You're also going to need a handheld light meter that can read flash output. Since most meters these days include a flash function that's not as bad as you might think, but because most cameras have built-in meters you may not own a separate meter. Welcome to the world of studio lighting! The meter is just the beginning of the other accessories you're going to need.
Why get a dedicated flash meter when you can use a multi-function meter such as Sekonic's L-758DR (right)? With a turn of a knob the L-758DR changes from an incident meter to a reflective spot meter for both ambient and flash measurements, all in one rugged, compact, all-weather housing
Joe Farace is the author of a new book called "Getting Started in Digital Imaging" published by Focal Press (ISBN 024080838X). It's available in all the best bookstores as well as Amazon.com.