Monolights, as I wrote about last week, combine power supply and flash head into a single unit. Another approach is used by power packs & heads systems that offer components as individual units that can be mixed and matched in different lighting set-ups.
Because there’s no internal power supply, flash heads can be smaller and some are downright tiny allowing you to place them in locations where larger monolights might not fit. Because these heads are smaller than a monolight, there’s room for cooling fans without the head size getting too large or the fan too big and noisy.
Another advantage is the power supply can control more than one head. Usually the output for each flash is controlled separately in either symmetric or asymmetric configurations. The power supply itself can be larger because the design needn’t be concerned as much about heat buildup affecting the flash head allowing more flash heads to be connected. Sometime you can get by with just one light as this set-up demonstrates.
The image at left was made using only a single Broncolor Litos head with 28-inch lightbank placed at camera left with no reflectors, as you see it above. The final image was made with a Canon EOS ID Mark IIN and EF 135mm f/2.8 SF lens with an Exposure of 1/60 sec at f/10 and ISO 100.
When using any studio flash system you’re eventually going to encounter a buzzword: lighting ratio. Lighting ratio is the difference in the brightness of light falling on your subject between the main or key and the fill light but there can also be tertiary lights that serve other purposes such as adding highlights to the subject’s hair or illuminating the background. Understanding this concept can be important with power packs that offer asymmetric controls that can be set for different output intensities.
A lighting ratio of 3:1 is considered “normal” for color photography but photographers can be flexible in applying this rule and to tell the truth I seldom worry about hitting a specific ratio.
For more on studio lighting techniques, please purchase up a copy of my book, “Studio Lighting Anywhere” for yourself or a friend. It’s is available from your favorite book or camera stores as well as including Amazon.com.