When it comes to lighting for photography, a lot of terms are usually thrown around that might create some confusion: strobe lighting, flash units, monolights, speedlights. When do you use a strobe instead of a speedlite? What is the difference between a strobe and a flash? Or a strobe and monolight?
First off photography lights are typically flash units. You can obviously also use continuous lights for photography but flash units are more practical. With continuous lights you have the advantage that you can see what you are getting before taking the picture, can be used with any camera (no need of a remote trigger or sync cord) and can be used for both video or stills. However, when shooting strictly photography indoors, continuous lights burn through more energy than flash units and can create discomfort for a model if they have to be in front of a hot light for several hours. So, in many scenarios, flash units are the way to go for photography. And if you need to see what you’re getting before taking the picture, most strobes use modeling lights to help you expose the right way.
So what are strobe lights? First off, the term “strobe lights”, when used for photography, is actually a misnomer. Strobe is short for “stroboscopic”, which is a device that produces regular flashes of light. So it’s a type of electronic flash light. When used for photography, flash unit and strobe light are basically the same thing. You connect them to your camera with a sync cord or remote trigger and they flash every time you take a photo.
There are a few types of flash units/strobes that are “speedlites” which mount on your camera’s hot shoe, and 2 main types of studio flash units, “power pack flash units”, which have the electronics in a power pack that connects to the wall and onto which you can connect several flash units, and “monolights”, which need to be plugged in directly into the wall and don’t use a power pack.
Speedlites are ideal in situations where you don’t have the time to set up an off camera flash and need to have more mobility. If your subject is already lit by other sources of lights, a speedlite can be used as a fill. However, options of modifiers for speedlites are usually limited and if you’re shooting in a dark environment and the speedlite is your main source of light, it could be hard to control the shadows.
Studio flash units, on the other hand, can add dimensionality to your photos, create separation and allow you to control shadows more effectively with also a wider selection of modifiers including umbrellas, soft boxes and beauty dishes. As mentioned earlier, there’s 2 types of off-camera flash units/strobes:
Power pack flash units - one example are the Profoto D4s flash lights that in order to operate need to be plugged in the Profoto Acute2 2400 power pack. The power pack then connects to the wall. All the electronics, including the capacitor, the intensity controls, sync cord ports, on/off switches are in the power pack and the flash lights pretty much only have the bulbs, modeling light lamp and the reflector. Some of the most powerful lights use this system as the bigger the power pack, the more powerful the light will be. If you’re using multiple flash units at the same time, this system makes it easier running AC cords to outlets as you’ll only need one outlet for the power pack. Ultimately, this option is usually preferred if you need as much power as possible.
Monolights - examples of monolights include the Elinchrome 1200RX and the Profoto B1x. These lights will carry the electronics on the light itself so in general they’ll usually be more limited in terms of power. Ultimately, if you use several flash units that you need to control separately and having to use several outlets is not an issue, monolights will work fine.
To conclude, most of the times the choice between power packs and monolights comes down to individual taste. The capabilities and features overlap considerably. In general, if you need the greatest possible power from a single flash head and mobility is not an issue, you get that with power pack units. If you need the greatest amount of compactness and separation of multiple heads, you get that from monolights.