The Varieties of Flash: Part II

Continued from The Varieties of Flash: Part I

Thyristor Circuitry

“A drain is a terrible thing to waste.”

Automatic flash units also offer the advantage of thyristor circuitry. The normal operation of a flash unit involves the use of capacitors and a transformer which discharge a high voltage charge through a xenon gas filled tube, thus emitting a bright and very momentary flash of light. In a normal manual flash, the capacitors would fully discharge, taking another full charge cycle until the flash is ready again. With thyristor circuitry, any remaining charge is saved, thus reducing the charge cycle time providing a faster recovery and extending battery life.

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Dedicated Flash Units

“I really want a flash that is monogamous.”

A dedicated flash unit offers advanced features that are specific to a camera brand. From the simplest feature, the dedicated flash can set your shutter speed to your cameraís flash sync speed and inform you when the flash is fully charged with an indicator in the viewfinder. To a more complex interaction with your camera which allows such features as setting the flash by adjusting your aperture, measuring the flash through the lens (TTL) instead of the flash sensor, setting fill flash by balancing ambient light exposure with flash exposure, and even offering a focus assist beam for auto focus SLRs.

As the features will vary by camera, I cannot give a rundown of dedicated flash functions; however, your manual will provide you with that information. If you do not have a manual, you can find features by experimentation. Support features will also vary by the make of the dedicated flash unit. Your manufacturerís flash will offer full functionality while an independent brand of dedicated flash for you camera may offer full functionality or have some features which are limited. With an independent make of flash, you need to check with your local dealer or the maker of the flash for which features are supported with your camera. The manual included with the flash should contain that information.

Flash Softly

“And carry a big stick”

As direct flash can be harsh such as producing a hotspot on your subject, it may be advisable to use a device to soften the output. This can be in the form of a diffuser which fits to the front of the flash lens and helps to spread the light giving a slightly softer light as well a wider angle of coverage. A more effective, but lossier method is to bounce the flash. With a bounce head flash, the head can be tilted up with a bounce card attached, which redirects the light forward and slightly down. Using a diffuser will reduce your effective available flash by 1 stop, and the bounce card will reduce it by1 Ω to 2 stops.

For bouncing the flash off a ceiling, there are two prerequisites: the ceiling has to be low; and the ceiling has to be white. To calculate the exposure for bouncing the flash, add the distance from the flash to the ceiling and from the ceiling to the subject to the distance the camera is from the subject. Set the flash for the correct range, providing you are using an automatic flash, and open the lens by one stop. If using manual mode, just open the lens one more stop than is indicated by the flash. It is best to tilt the head of the flash unit straight up when bouncing off of a ceiling, otherwise the bounced light may fall too far behind your subject. When bouncing off a ceiling, have your subject no closer than twice the distance between the flash unit and the ceiling. If you have to work closer than that, try using a reflector to bounce some light back onto your subject from the front. If the ceilings are over 10 high, forget it unless you have a powerful enough flash unit. An advantage of using ceiling bounce is that it can throw light into the background keeping it from being dark.

Since there are a variety of bounce options you can get for your flash, variations in light loss as well options for combining frontal and ceiling bounce will offer different effects. As such, you should become familiar with the device you use as most of them should come with an instruction sheet informing you of the most common amount of light loss to be applied. There are also a variety of diffusion options available from diffusion filters to soft boxes for your portable flash.

Take It Off

“Take it all off… booga… booga.”

For a more flattering light on your subject, the flash unit can be removed from the camera, provided you have a PC cord or a dedicated flash cord. If you do not have a PC connector on your camera, you can purchase a hotshoe adapter which slides into your hotshoe and provides a PC connector.

The most basic method of off camera flash is holding the unit in your hand at arms length, slightly off to the side. It does take practice to get used to aiming the flash at your subject. One method is to forget that the flash is in your hand, and, instead, focus holding your palm in the subjectís direction. If you are using direct flash, you can lay your index and middle fingers over the top of the flash and use them as pointers to keep from aiming the flash too high or too low.

Using a flash bracket, such as those manufactured by Stroboframe, is a handy way to move the flash several inches off the camera while maintaining the use of your hands. Some of the better brackets allow the flash to reside directly above the lens and permit the camera to be switched from a horizontal to a vertical position while maintaining the flash in a position directly above the lens. This helps to reduce shadows and eliminate redeye. Combined with a diffuser or bouncer, the flash bracket can provide many benefits in a compact package.

Using a light stand for your flash unit can provide another method of taking the flash off the camera. With this method, you can position the flash where you want it in relation to the camera. Using this method can provide contrast within your subject which may be flattened by the more even lighting provided when the flash is directly above the camera. Use of a pop-out reflector with off camera flash increases the choices of lighting which you have by providing light to give detail to your subject yet filling in shadows to give a softer effect.

A slave flash unit, which allows one flash to be triggered by another flash, can be used to combine the effects of two flash units. One effective and simpler method of using a slaved flash is to use a trigger flash mounted on your camera and a slaved flash on a light stand off to the side of the camera (having the slave flash placed at a 30 degree angle in relation to your subject is effective for this purpose, but you can experiment with an angle of 30 to 45 degrees). If your camera mounted flash has a guide number in the range of 72-93 and your slaved flash has a guide number of 120, this will provide a, roughly, one stop difference between the units, using the on camera flash as a fill.

Rather than using manual flash units, you can use two automatic flash units. Set the on camera flash unit for one stop less exposure than the off camera flash unit. Although conventional wisdom will tell you not to do this because the two units may interfere with each otherís sensors, with this method, they will not interfere.

Ambient Light

“Ahhh have seen the light!!”

Ambient light is simply the amount of available light within a scene. When using flash, we can end up exposing for the flash only and end up with a well exposed subject against an underexposed background. To adjust for this, we can measure the available light in the scene and expose for that. Then we can set our flash at a complimentary range for the set aperture or slightly above the set aperture (1/2 to 1 stop) to properly expose the scene while highlighting our subject. We can do this because the light a flash emits is at a set value and is not affected by the shutter speed as the duration of the flash is roughly around 1/1000 of a second or higher.

A technique that is used in wedding photography is setting the aperture to match the flash output (usually F8) and shooting with a shutter speed of 1/30 of a second. This allows the capture of ambient light in a higher percentage of shots. This is only used with a normal or wide angle lens as a longer lens or a zoom may cause too much shake. Although the subjects will be stable, since the flash freezes the motion, with a longer lens, background objects may be blurred or ghosted (double images). This technique is commonly referred to as ëdragging the shutterí.

Many of todayís cameras have built in features which automate the use of flash with ambient light. The Slow Sync flash mode of some models sets the exposure for the background and sets the flash to highlight the foreground. Having the feature built in can free up the photographer from having to make calculations, while offering the novice an additional tool for a technique they have yet to learn. Slow Sync flash can be used for special effects as well. By using the mode with a moving subject against a background which requires a slow shutter speed, you can freeze the motion of the subject while giving a streaking blur to the background emphasizing motion. The Slow Sync flash mode is most often used the same as exposing for ambient light; the camera exposes for a dark background while highlighting the foreground with flash.

When using the flash as a fill to reduce harsh contrast in a brightly lit scene, such as daylight, it is advisable to set the flash for one stop less exposure than the ambient light. If you cannot shoot at a slow enough shutter speed to maintain flash sync in a bright outdoor situation, you can use Neutral Density filters to bring down the shutter speed.

The Mystery Camera

“That car still doesnít belong.”

In a move, which was poorly orchestrated, my Anscoflex rig was included in a group of items sold to a flea market dealer, without my knowledge. I was not longing for my missing camera, however. Many years later, I was watching an episode of Cheers, I believe it was Carlaís wedding, as Cliff was running around with a camera; it was my camera. I cannot say that it was specifically my camera, but, what is the chance that someone took the same model camera (and old one at that), flash, and bracket; then rigged the flash in the same manner. It just seemed odd.

The Wrap Up

“Put a bow on it.”

The information which I have provided is a combination of learned knowledge, experience, and very probably some bad habits, which I like to call rules of thumb since it makes it sound better. This is not a comprehensive coverage of electronic flash, just an introduction to some equipment, concepts, and confusables. There are various sources of information on advanced flash techniques available with which the knowledge can enhance your photographic skills. As well, the manual included with your flash will provide information about the features offered by your flash and specific operating instructions. I have at least attempted to provide a very basic introduction and hope it has been successful in that regard.