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Studio flash

A primer on what's available


A self-contained studio flash unit (a
A self-contained studio flash unit (a "mono-light") has power pack and flash head built into one unit that can be attached to a light stand. This particular light's controls are located on a back panel. Some are located on the sides.

There are two basic types of electronic flash systems for the studio:

  • Self-contained flash heads or "mono-lights" (flash head and power supply combined in one unit), and
  • Separate power pack systems (flash head and power supply are different units). Photographers may refer to flash heads and power supply units simply as "heads" and "packs."

SELF-CONTAINED FLASH HEAD

The self-contained flash head's main advantages are simplicity and compactness. Its relatively-small size and light weight make it ideal for taking on location with the minimum fuss. However, its power output is usually less than that of a separate power pack system, with levels of illumination measured in the range of 100 watt-seconds to 1,000 watt-seconds. Some self-contained flash heads can be operated from batteries, but most require connection to normal household current.

The unit's operating controls are generally located on a rear panel, but could also be placed on the side. The entire fixture is typically attached to a light stand. Various reflectors and shades can usually be affixed directly to the unit. The self-contained flash head is generally less-expensive and less powerful than systems that employ a separate power pack.


SEPARATE POWER PACK FLASH SYSTEM

The flash head and power supply units are connected to one another by electrical cable. Operating controls are located on the power pack, although the flash head may contain a simple on/off switch for its modeling light.

Some power packs are fairly small, weighing as little as five pounds, and therefore easily-portable, making them useful away from as well as inside the studio. Others are quite large and cumbersome. The heavier units are usually placed on a rack or dolly equipped with casters in order to move them more easily. Power packs may deliver levels of illumination measured in the range of 500 to 20,000 watt-seconds.

Most power supply units have a number of outlets for connecting more than one flash head. The operating controls may permit the photographer to select different power output settings for each flash head or for groups of flash heads, thereby controlling lighting ratios without having to move the lights closer to or further from the subject to increase or decrease their illumination levels.

A power pack has plug-in sockets to attach leads to the flash heads. This unit has four such sockets, for four flash heads, although only two are connected. Note the number of controls for varying the intensity of the light from the flash heads.
A power pack has plug-in sockets to attach leads to the flash heads. This unit has four such sockets, for four flash heads, although only two are connected. Note the number of controls for varying the intensity of the light from the flash heads.

The modeling light for this self-contained flash head (with its reflector removed) is the large central bulb. The actual flash tube is circular, and surrounds the modeling light.
The modeling light for this self-contained flash head (with its reflector removed) is the large central bulb. The actual flash tube is circular, and surrounds the modeling light.

MODELING LIGHTS

Flash heads used in either system may have a built-in modeling light, which does not provide flash illumination. A modeling light is a second lamp, generally a tungsten or quartz bulb, that provides continuous illumination of the subject, enabling the photographer not only to accurately focus, but also to view the direction of the light that will be produced by the flash.

High-quality flash heads have modeling lights of variable illumination levels, enabling the photographer to set lighting levels for each unit's modeling light that compare with the ratio of the much brighter output from the flash heads. Pre-judging the intensity of each flash head's output is useful in evaluating the effect on the subject of a particular lighting set-up, enabling the photographer to fine-tune highlight and shadow illumination.


OPERATION

Although studio flash systems may at first seem complicated, they are generally simplicity itself to operate. You don't need a specialist's certificate, by any means, although there is a good deal of artistry associated with the use of a flash system in making beautifully-lit photographs.

In the simplest scenario,

  • the flash head is mounted on a stand and aimed at the subject, or at a reflector that is aimed at the subject,
  • it is connected to a power supply (an electrical outlet, if it is a self-contained flash head, or a separate power pack, which itself is then connected to an electrical outlet),
  • a sync cord connected to the camera is attached to the flash head's or the power pack's sync terminal,
  • the power switch is turned on, which causes the flash head's modeling light to light up,
  • a ready light on either the power pack or on the flash head comes on, usually accompanied by an audible signal - a beep that tells you the flash is at 100% readiness and can now be set off,
  • the camera's shutter is depressed, sending an electrical charge through the sync cord that triggers the flash.

    That's it. It is that easy. Within a short delay, typically around a second or so, the flash unit's ready light will come on and you will hear the beep that tells you the unit has recycled and there is sufficient power to operate the flash again.

  • This flash head is in ready mode. Its modeling light (the bright bulb in the center) is illuminated, giving you sufficient light to see what the flash will illuminate and to focus. As soon as you trip the shutter, the round flash tube will ignite.
    This flash head is in ready mode. Its modeling light (the bright bulb in the center) is illuminated, giving you sufficient light to see what the flash will illuminate and to focus. As soon as you trip the shutter, the round flash tube will ignite.

    This flash head was ignited without a direct sync cord connection to the camera. It has a built-in slave detector that senses when another flash has gone off, causing it to go off, too.
    This flash head was ignited without a direct sync cord connection to the camera. It has a built-in slave detector that senses when another flash has gone off, causing it to go off, too.

    MORE THAN ONE FLASH HEAD

    You may wonder how, when using a self-contained flash head system, you trigger a second or third flash head when there is only one sync cable connected to the camera.

    There is more than one way to trigger a flash head (or even a power pack) than just using a sync cable connection. The most popular is to use a photo cell that senses the light from the first flash and instantly triggers the second flash. Most good quality, modern flash heads and power packs have such photo cells ("slave eyes") built in, and contain a switch that determines whether they are to be triggered by a sync cord or from the photo cell. The slave eye is sensitive to electronic flash and may also receive and activate from an infrared transmission.

    You can, in fact, even do away with the sync cord altogether by connecting a small flash unit to the camera and using its burst of light to trigger the studio flash via the system's photo cell(s), provided the illumination from the camera-mounted flash is significantly weaker than the studio system's. You can also attach a small infrared transmitter to your camera's hot shoe and an infrared receiver to the flash head or power pack to trigger the system.

    You can also trigger most studio flash units manually by pressing the ready-light switch.


    Further information...

    Exposure using studio flash

    Studio lighting accessories
    Related topics...

    Flash-to-subject distance