Glossary

 
 
  A-TTL
  A trademark for some implementations of Canon's TTL (through the lens) flash metering system. Quantum offers dedicated QTLL adapters that make Qflash compatible with the A-TTL system, while offering more power, in a rugged, heavy-duty package.
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  A/C Mains Adapter
  Plugs into wall outlet, allows flash to operate on a continuous A/C Mains Outlet. Permits all-day operation without need to recharge battery.
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  A/C Mains Outlet
  Wall-outlet power. A/C stands for "alternating current," the type of power available from wall outlets. Varies from country to country, anywhere from 110-240 volts. With the proper adapter, permits operation of flash and/or camera without battery power.
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  A/C Power
  A/C stands for "alternating current," the type of power available from wall outlets. Varies from country to country, anywhere from 110-240 volts. With the proper adapter, permits operation of flash and/or camera without battery power.
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  Aperture-Preferred Mode
  A camera automatic exposure mode. Photographer
chooses the desired, "preferred," lens aperture, camera automatically chooses appropriate shutter speed to provide correct exposure.
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  Auto Fill
  Automatic flash exposure that balances flash illumination with ambient light, and provides the photographer with control of the amount of fill flash. It is available on Quantum Qflash, and works in conjunction with Quantum dedicated QTTL adapters available for most modern cameras. Auto Fill automatically tracks the lens aperture you set, and permits control of the flash fill illumination in 1/3-stop increments.
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  Auto Mode on Flash
  Flash exposure is automatically controlled by a sensor on the flash, as opposed to TTL Flash where the flash exposure is automatically controlled by the camera. Automatic mode provides excellent flash exposure for cameras without TTL Flash, and for some multi-light setups.
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  Auto-Sensing Voltage
  Many Quantum Batteries will provide power to both a flash and to a digital SLR camera. When used with the appropriate cables, Quantum's Auto-Sensing technology will supply the correct voltage to the camera and/or flash.
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  Automatic
  Auto Mode on Flash
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  Automatic
  Flash exposure is automatically controlled by a sensor on the flash, as opposed to TTL Flash where the flash exposure is automatically controlled by the camera. Automatic mode provides excellent flash exposure for cameras without TTL Flash, and for some multi-light setups.
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  Bare Bulb
  Eliminates the normal reflector surrounding the flashtube, allowing light to radiate in all directions, not just in the standard forward direction. Preferred by some photographers for indoor shots, where bare-bulb light bounces off walls and ceiling, creating soft fill illumination, while at the same time achieving brightness on the subject and sparkle in the eyes from the direct light also coming from the flashtube.
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  Battery Memory
  A characteristic of certain types of batteries, notably Nickel- Cadmium ("NiCad"), to deliver less-than-expected power if charged before being fully discharged. Such batteries required a fair amount of attention to achieve optimal results. All Quantum batteries use modern battery technology that eliminates "battery memory" problems. If needed, Quantum Batteries can be charged to "top off" before a big assignment.
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  Blow Out
  The tendency of automatic flash exposure systems to severely overexpose, or "blow out", the subject, particularly when the subject is far from the center of the frame. Quantum's Qflash eliminates this problem - and still provides automatic exposure control - by allowing the photographer to set the approximate flash-to-subject distance with the Sensor Limit feature.
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  Bounce Flash
  Flash is aimed at a wall or ceiling rather than aimed straight-ahead (direct flash). This provides softer light since the "source" of light is now a large diffuse surface. Additionally, the illumination now comes from the side or top, adding realistic texture and three-dimension, a more natural-appearing illumination than direct flash. Aiming the flash into an umbrella or softbox provides similar lighting quality.
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  Channel
  When the connection between camera and flash is wireless, communication is via infrared or radio waves. The particular frequency of waves (like tuning a radio) is called the channel. A wireless system with more than one channel has two advantages: #1) It prevents interference if other photographers in the area are also using wireless systems, and #2) in a multi-flash setup, flash units can be independently controlled and set to turn on or off from the "master" or "commander" flash. Combining a choice of eight channels along with four available zone settings, Quantum's FreeXwire wireless systems offers a total of 256 possible combinations.
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  Charger
  Plugs into a wall outlet and charges Quantum Turbo- and QB-series portable batteries/ power packs. All Quantum batteries come with a standard charger appropriate for country of sale. In addition, optional chargers are available for other countries, as well as vehicle and rapid chargers for many Turbo and QB batteries.
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  Coverage Angle
  The angle of the cone of light put out by a flash. In general, for direct flash, the beam angle of the flash must be at least as wide as the angle of view of the lens being used. For example, a "normal" camera lens typically sees approximately a 45 degree field of view. The normal reflector on a Quantum Qflash puts out a beam of light about 55 degrees wide, more than adequate for most wide-angle lenses. For extreme wide-angle lenses, an optional wide-angle diffuser is available, and for photography using telephoto lenses, there is the optional telephoto reflector.
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  D-TTL
  A trademark for some implementations of Nikon's TTL (through the lens) flash metering system. Quantum offers dedicated QTTL adapters that make Qflash compatible with the D-TTL system, while offering more power, and in a rugged, heavy-duty package.
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  Dedicated Flash
  A flash unit built specifically to read the TTL (Through-The-Lens) Exposure information from a particular camera. Camera and flash operate as a "dedicated" pair, providing proper normal and fill flash exposure, and a range of controls for single-and multiple-flash setups. Quantum's Dedicated QTTL Adapters turn a Quantum Qflash into a dedicated unit for many popular cameras.
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  Dedicated TTL
  A flash unit built specifically to read the TTL (Through-The-Lens) Exposure information from a particular camera. Camera and flash operate as a \"dedicated\" pair, providing proper normal and fill flash exposure, and a range of controls for single-and multiple-flash setups. Quantum\'s Dedicated QTTL Adapters turn a Quantum Qflash into a dedicated unit for many popular cameras.
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  Diffuser
  White translucent material placed in front of the flash head that softens and spreads out the light.
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  Digital SLR
  Also written DSLR and D-SLR. A digital camera incorporating Single Lens Reflex viewing and exposure. Light from the subject goes through the camera lens, reflects off an internal mirror and goes to the eyepiece. At the instant of exposure, the mirror temporarily flips out of the way, allowing light from the lens to go directly to the digital sensor. This provides a very bright viewfinder, and very accurate preview of the final image composition, one that faithfully shows the effect of whatever focal-length lens is chosen.
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  Duty Cycle
  In relation to flash, indicates the number of times a flash may be fired in rapid succession before it overheats, leading to misfiring, or worse. Quantum Qflash are built with the professional photographer in mind and have heavy-duty components throughout. The duty cycle of Qflash far exceeds those of camera manufacturer's flashes. A Qflash can be run non-stop, flash after flash after flash - even at full power- with no adverse effects.
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  E-TTL
  A trademark for some implementations of Canon's TTL (through the lens) flash metering system. Quantum offers dedicated QTTL adapters that make Qflash compatible with the E-TTL system, while offering more power, in a rugged, heavy-duty package.
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  E-TTL2
  A trademark for some implementations of Canon\'s TTL (through the lens) flash metering system. Quantum offers dedicated QTTL adapters that make Qflash compatible with the E-TTL system, while offering more power, in a rugged, heavy-duty package.
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  Electrical Memory
  A characteristic of certain types of batteries, notably Nickel- Cadmium (\"NiCad\"), to deliver less-than-expected power if charged before being fully discharged. Such batteries required a fair amount of attention to achieve optimal results. All Quantum batteries use modern battery technology that eliminates \"battery memory\" problems. If needed, Quantum Batteries can be charged to \"top off\" before a big assignment.
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  Fill Flash
  The style of adding flash illumination to a basic ambient- or natural-light scene. Often used to brighten up a dark foreground, or even out blotchy sunlight on a portrait, or make the subject stand out from the background.
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  First-Curtain Sync
  The electrical trigger signal from the camera that fires, or \"synchronizes,\" the flash at the moment the camera\'s first (or \"front\") shutter curtain opens to expose the entire frame. Shutters on SLR cameras consist of two \"curtains,\" one opens to expose the digital sensor (or film), followed by a second curtain that covers the sensor. When shutter speeds slower than the camera\'s sync speed are used, some cameras allow the flash synchronization to trigger the flash just prior to the second, or rear, curtain beginning to close.

In most situations, there is no difference in appearance. However, when photographing moving objects with slow shutter speeds, say, in sports, second-curtain sync will properly place motion-blur streaks behind the subject, whereas if first-curtain sync is used, the object appear to be going backwards because the motion-blur streaks are now in front of the subject.
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  Flashtube
  The component of a flash unit that produces the actual light (created by an electrical spark in a xenon-gas filled tube). Quantum uses heavy-duty flashtubes, which plug into the reflector, and are easily user-replaceable.
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  Frame Rate
  The number of shots per second. Some professional cameras are capable of frame rates as high as five or more frames per second. Quantum high-voltage Turbo-series of batteries are quite capable of providing bursts of flash shots at these high frame rates, when the flash is in Automatic or TTL mode and at moderate distances and larger apertures.
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  FreeXwire
  Quantum's system for wireless communication and control between camera and one or more flash units (Quantum flash or other brands). More than just a triggering device, it offers TTL control of the relative output of one or more Qflash units. FreeXwire may also be used to remotely trigger cameras.
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  front- and rear-curtain sync
   
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  Front-Curtain Sync
  The electrical trigger signal from the camera that fires, or "synchronizes," the flash at the moment the camera's first (or "front") shutter curtain opens to expose the entire frame. Shutters on SLR cameras consist of two "curtains," one opens to expose the digital sensor (or film), followed by a second curtain that covers the sensor. When shutter speeds slower than the camera's sync speed are used, some cameras allow the flash synchronization to trigger the flash just prior to the second, or rear, curtain beginning to close.

In most situations, there is no difference in appearance. However, when photographing moving objects with slow shutter speeds, say, in sports, second-curtain sync will properly place motion-blur streaks behind the subject, whereas if first-curtain sync is used, the object appear to be going backwards because the motion-blur streaks are now in front of the subject.
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  Fuel Gauge
  LED lights on all Quantum batteries that indicate remaining capacity or battery charging status.
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  Full-Power Flash
  Modern flash units can vary their light intensity, anywhere from maximum "full power" to a small fraction, typically down to 1/32- or 1/64-power. At full power, the flash draws maximum energy from its battery, decreasing the number of shots per battery charge and correspondingly increasing its recycle time. When a flash is used in Automatic or TTL mode, its output power is automatically controlled to ensure proper exposure. For far distances, small lens apertures, bounce flash and/or low ISO settings, full power, or close to full power, is required. However, at moderate or close distances, medium and large lens apertures, and/or high ISO settings, far less flash power is required. When less-than-maximum power is needed, batteries can provide far more flashes per charge, and recycle time decreases considerably. Generally, a battery is rated by the number of full-power flashes it can deliver.
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  Guide Number
  Is an indication of the effective brightness of a flash, and is a number provided in the specifications by the flash manufacturer. Guide numbers are listed for both feet and meters, and usually for ISO 100 (but not always!). To fairly compare two flash units in terms of effective brightness, it is important to know how the manufacturer determined the guide number value: what ISO, what angle of coverage, and evenness of illumination. Small differences in guide numbers are immaterial; two guide numbers would have to differ by about 70% before there would be one full stop exposure difference.

The guide number is also used to determine the f/stop when a flash is used in manual mode. The flash-to-subject distance is simply divided into the guide number, yielding the f/stop. On modern portable flash units, like the Quantum Qflash, the arithmetic has been done for you, with a readout on the LCD screen indicating the proper f/stop for a given distance.
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  Handle-Mount Flash
  A style of flash unit having a flash head attached to a long vertical handle. Many handle-mount flashes will also work with Quantum batteries, which provide much greater capacity and much shorter recycle time.
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  High-speed sync
  The standard sync speed of a camera is the fastest shutter speed allowed for standard flash photography (typically 1/125 - 1/250 for modern cameras - check your camera's instruction manual). Some camera manufacturer's flash/camera combinations can be used for flash photography at speeds higher than the sync speed by emitting a very rapid series of relatively weak flashes. This is usually limited to fairly close distances and/or moderate-to-large apertures.
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  High-Voltage Batteries
  Traditional flash units use low-voltage 1?-volt batteries in clusters of four, providing 6 volts. Since a flashtube requires 325 volts to fire, electrical circuits within the flash unit "step up" the low voltage. This is done using an inverter, which produced the high-pitched whine audible when the flash is recycling, but taking many seconds to do so. Quantum's TURBO line of batteries produce 325 volts, completely bypassing the low-voltage step-up circuit, and leading to recycle times often measured in fractions of a second when the flash is in Automatic and TTL modes.
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  Hot Shoe
  The fitting on top of the camera designed to support a shoe-mounted flash or other accessory. The hot shoe has one or more electrical contacts, which transfers synchronization and/or exposure information to the flash unit or to a TTL adapter. These electrical contacts are called "hot spots," hence the term hot shoe. "Cold shoes" also exist, which are just mechanical supports for the flash.
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  i-TTL
  A trademark for some implementations of Nikon's TTL (through the lens) flash metering system. Quantum offers dedicated TLL adapters that make Qflash compatible with the i-TTL system, while offering more power, in a rugged, heavy-duty package.
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  Infrared Focus Assist
  Camera autofocus systems have difficulty focusing in dim light. Since flash is often used under such conditions, some dedicated flash units emit infrared (invisible) light to assist the camera to focus. Quantum's dedicated QTTL adapters, when used in conjunction with Quantum's Qflash, emit infrared light that responds to the camera's focusing signals.
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  Infrared TTL
  Some camera manufacturers offer flash units that can wirelessly communicate with their identical units in a multi-flash setup. Communication is via an infrared signal, similar to the remote-control for a television. Quantum's QNexus can read these signals from Nikon and Canon flash units, permitting Quantum Qflash to be used as remote satellite units, offering fast recycling, more power and much stronger duty cycle than camera manufacturer's flash

To greatly increase distance and reliability, consider Quantum\'s FreeXwire system, which uses radio-frequency waves rather than infrared, and that can read the TTL signals from many modern cameras.
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  Infrared Wireless
  Infrared TTL
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  ISO
  (International Organization for Standardization ) an internationally-recognized method to rate a film's "speed," its sensitivity to light. Digital cameras have "ISO equivalent" settings. Higher ISO means more sensitivity to light; therefore, under any given condition, you can use higher shutter speeds and/or smaller apertures. With flash, higher ISO also translates into the ability to shoot at farther distances, or to draw less battery power for a particular shot, thereby decreasing recycling time and increasing the number of shot per battery charge.
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  Key Light
  The main light, the principal source of illumination. It is usually the brightest or the one having the greatest overall effect on the scene. By implication, there are also one or more additional lights, used for fill or to create highlights.
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  LCD Screen
  Liquid Crystal Display. Screen on back of flash that displays user information, settings and menu choices. Also refers to the various viewing and information screens on cameras.
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  Light Bank
 
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  Low-Voltage Battery
  Traditional 1?-volt batteries, used in clusters of four to six, providing 6-9 volts to flash units Quantum's QB-series batteries provide this same low-voltage to replace the "AA" or "C" or "D" cells in a flash, but with far greater capacity for more shots and faster recycling time (Quantum's TURBO series of high-voltage batteries, offering even higher capacity and extremely fast recycling time.)
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  Mains A/C Power
  Wall-outlet power.
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  Manual
  With camera operation, refers to setting both shutter speed and f/stop manually by the photographer, rather than using an automatic exposure mode. With flash, refers to the photographer setting the exact power of the flash, or setting the f/stop based on flash-to-subject distance, bypassing any automatic exposure mode. Manual flash exposure is usually used in conjunction with a handheld light meter, or after exposure tests with a digital camera.
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  Manual Mode
  With camera operation, refers to setting both shutter speed and f/stop manually by the photographer, rather than using an automatic exposure mode. With flash, refers to the photographer setting the exact power of the flash, or setting the f/stop based on flash-to-subject distance, bypassing any automatic exposure mode. Manual flash exposure is usually used in conjunction with a handheld light meter, or after exposure tests with a digital camera.
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  Overexpose
  More light than necessary, which creates an image that looks too light, too washed out, with no detail in the skin tones and other light areas. With flash, it can be caused by a scene having a distant background while the main foreground subject is on the periphery of the frame. Automatic and TTL exposure systems tend to "see" the entire area of the frame, and therefore attempt, in this example, to expose for the background, the background needing far more flash power than the foreground. The Sensor Limit feature of Quantum's Qflash used in conjunction with the Automatic mode can prevent this type of overexposure.

Another cause of flash overexposure is being closer than the allowed distance when shooting in automatic or TTL mode. For each chosen f/stop, there is a near-to-far-range that will provide proper exposure (the range is indicated on the LCD panel on the flash). Closing the aperture and/or lowering the ISO will allow the flash to provide proper exposure at close distances.
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  Pre-flash Metering
  A system for TTL flash exposure that sends out a low-brightness flash immediately prior to the main exposure; it happens so rapidly, it is usually unnoticeable. The pre-flash allows the camera's TTL metering system to accurately calculate the correct amount of main flash burst. Pre-flash metering provides excellent results, but is only available on higher-level cameras with appropriate TTL flash metering systems. Quantum offers dedicated QTTL adapters that provide pre-flash metering for all cameras so equipped.
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  Program
  Camera has full control setting the shutter speed and lens opening.
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  Program Mode
  A setting on Quantum Qflash that allows the photographer to preset a group of frequently-used conditions: f/stop, ISO, exposure mode, fill-in flash amount, and manual power setting. Up to eight separate Pre-Sets can be programmed. Then, with a few button presses, any of the programs can be quickly retrieved. (Qflash "Program" mode is distinct from a camera "P" or "Program" mode.)
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  Qflash
  Quantum's line of portable, professional-caliber, high power flashes.
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  Qnexus
  Quantum's wireless system that permits powerful Quantum Qflash to be used in conjunction with a Nikon or Canon flash for an automatic flash exposure system that mimics the multi-flash wireless controls of Nikon and Canon units. The Nikon or Canon flash acts as the "commander" or "master," sending out infrared control signals that are picked up by the QNexus receiver plugged into a Qflash.
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  QTTL
  Quantum's special twist on TTL.
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  QTTL Adapter
  Quantum's QTTL adapter that plugs into the hot shoe of many cameras and reads the TTL (Through-The-Lens) flash exposure signals generated by the camera. This communicates flash exposure information to Quantum's Qflash, allowing the Qflash to mimic the features of the camera manufacturer's flash, but in a much more powerful, versatile and robust package.
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  Radio Trigger
 
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  Ratio Fill-in Flash
  Fill-in flash is the style of adding flash illumination to a basic ambient- or natural-light scene. It is often used to brighten up a dark foreground, or even out blotchy sunlight on a portrait, or make the subject stand out from the background. It is important to be able to vary the relative amount of light - the ratio - between the ambient and the fill-in flash. Quantum's dedicated QTTL adapters, available for most cameras, allow total control of the ratio of natural light to fill-in flash, in 1/3-stop increments, while using the camera's TTL metering system.
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  Ratio Flash
  In multiple-flash setups, ratio flash indicates the relative brightness, or ratio, of each flash. If one flash is set for full power and a second flash to half-power, the ratio would be 1:2. The relative power of multiple Qflash can be set in automatic mode on each unit, or adjusted wirelessly from the camera position using Quantum's FreeXwire or QNexus wireless systems. (QNexus works in conjunction with some Nikon and Canon flash units.)
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  Rear-Curtain Sync
  The electrical trigger signal from the camera that fires, or "synchronizes," the flash at the moment the camera's second (or "rear") shutter curtain opens to expose the entire frame. Shutters on SLR cameras consist of two "curtains," one opens to expose the digital sensor (or film), followed by a second curtain that covers the sensor. Normally (the camera is set to first- or front-curtain sync) the flash fires as soon as the first curtain is fully open. However, when shutter speeds slower than the camera's sync speed are chosen, some cameras allow the flash synchronization to trigger the flash just prior to the second, or rear, curtain beginning to close.

In most situations, there is no difference in appearance. However, when photographing moving objects with slow shutter speeds, say, in sports, rear- or second-curtain sync will properly place motion-blur streaks behind the subject, whereas if first-curtain sync is used, the object appear to be going backwards because the motion-blur streaks are now in front of the subject.
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  Receiver
  A wireless device that can be used to receive wireless signals which trigger a remote flash or camera. Quantum's FreeXwire FW7Q and FW8R receivers or FW10W transceiver can be used to fire a remote Qflash, including all TTL exposure information. Receiver model FW8R and transceiver FW10W will also trigger many other brands of flash. Both FW8R and FW10W can also trigger a remote camera. To complete the package, a compatible FreeXwire transmitter FW9T, is required to send the signal from the camera or operator.

Quantum's QNexus receiver plugs into a Quantum Qflash 5d-R and reads infrared TTL signals transmitted by certain Canon and Nikon flash units.
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  Recycle Time
  The time it takes a flash to recharge before the next photo can be taken. It is a function of the type of battery used, the charge condition of the battery, and how much power was just used to take the first photo.

If a flash is used in automatic or TTL mode, and at moderate distances, the flash does not use a full charge, therefore electrical energy is conserved in the flash, and it can recycle fairly rapidly. But if a full charge is required - bounce flash, far distances, small lens apertures - recycle time will be proportionally greater.

Quantum Turbo batteries, operating at high voltage, provide recycle times often measured in fractions of a second when used in automatic or TTL modes at moderate distances.
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  Remote Flash Unit
  One or more additional flash units that fires simultaneously with the main Master flash, usually placed away from the camera. May be hardwired to the main unit, or triggered wirelessly.
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  Remote Head
  A flash head that is separate from the main body of the flash. Allows creative lighting effects when the remote head is hidden behind objects or inside a product. Particularly useful for architectural and studio photography.

Quantum offers a remote head on an 8-ft. (2.5 m) cable that plugs into a Qflash and retains all automatic and TTL features.
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  Satellite Flash
 
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  Second-Curtain Sync
  The electrical trigger signal from the camera that fires, or \"synchronizes,\" the flash at the moment the camera\'s second (or \"rear\") shutter curtain opens to expose the entire frame. Shutters on SLR cameras consist of two \"curtains,\" one opens to expose the digital sensor (or film), followed by a second curtain that covers the sensor. Normally (the camera is set to first- or front-curtain sync) the flash fires as soon as the first curtain is fully open. However, when shutter speeds slower than the camera\'s sync speed are chosen, some cameras allow the flash synchronization to trigger the flash just prior to the second, or rear, curtain beginning to close.

In most situations, there is no difference in appearance. However, when photographing moving objects with slow shutter speeds, say, in sports, rear- or second-curtain sync will properly place motion-blur streaks behind the subject, whereas if first-curtain sync is used, the object appear to be going backwards because the motion-blur streaks are now in front of the subject.
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  Sensor Limit
  Many flash units, when in automatic or TTL mode, will cause severe overexposure when the subject matter is far from the center of the frame, and the background is very far from the main subject. The unique sensor limit setting of the Quantum Qflash will prevent overexposure when the photographer dials in the approximate flash-to-subject distance, effectively telling the flash to disregard the distant background.
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  Shoe-Mount Flash
  A portable flash that has a "foot" that slides into the grooved hot shoe on top of most SLR cameras. The electrical contacts that trigger the flash, and often control exposure through the camera, are located on the bottom of the foot.
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  Shutter-preferred
  Chose a shutter speed, the camera sets the lens opening.
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  Shutter-Preferred Mode
  A camera automatic exposure mode. Photographer
chooses the desired, "preferred," shutter speed, camera automatically chooses appropriate aperture to provide correct exposure.
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  Slave
  An inexact term in flash photography that usually refers to A) one or more satellite or remote units, which are triggered by the main Master flash, or B) the actual wireless device that triggers the remote flash. Quantum's Qflash, when used as a slave, can be triggered by a light pulse from another flash, by an infrared signal using the QNexus receiver or by radio signals using FreeXwire components.
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  SLR
  Stands for Single Lens Reflex camera. Light from the subject goes through the camera lens, reflects off an internal mirror and goes to the eyepiece. At the instant of exposure, the mirror temporarily flips out of the way, allowing light from the lens to go directly to the digital sensor (or film). This provides a very bright viewfinder, and very accurate preview of the final image composition, that faithfully show the effect of whatever focal-length lens is chosen.. Most 35mm-size and medium format cameras that have interchangeable lenses incorporate this system, the main exception being Leica rangefinder cameras. If the camera is digital, often the abbreviation is written DSLR or D-SLR.
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  Snoot
  A cylinder that fits onto a flash to create a very narrow spotlight beam of light.
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  softbox
  Some camera manufacturers offer flash units that can wirelessly communicate with their identical units in a multi-flash setup. Communication is via an infrared signal, similar to the remote-control for a television. Quantum's QNexus can read these signals from Nikon and Canon flash units, permitting Quantum Qflash to be used as remote satellite units, offering fast recycling, more power and much stronger duty cycle than camera manufacturer's flash

To greatly increase distance and reliability, consider Quantum\'s FreeXwire system, which uses radio-frequency waves rather than infrared, and that can read the TTL signals from many modern cameras.
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  Strobo Mode
  Rapid, periodic multiple flash bursts that create photographs with a stroboscopic look (multiple overlapping exposures, or a sequence of exposures on the same frame). Quantum Qflash Strobo Mode is adjustable from 1 to 50 flashes per second, and from 1 to 20 flashes per sequence.
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  Sync
  Shorthand for "synchronization." A flash must be fired at the exact moment that the camera shutter is fully open. A sync signal is sent to the flash from the camera at the appropriate moment, synchronizing the shutter with the flash. Also see sync speed.
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  Sync Speed
  The maximum camera shutter speed that can be used with flash. For portable flash, this is determined by the camera manufacturer, which, for modern digital SLRs is typically 1/150-1/250 sec. Consult your camera manual! Quantum Qflash will automatically prevent the shutter speed from being higher than the sync speed when the appropriate Quantum TTL adapter is used for your camera.
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  Telephoto Reflector
  A specially-shaped accessory reflector that goes behind the flashtube and greatly increases the distance range of the flash. It is generally used with telephoto lenses for photographing wildlife and sports, though many photographers use it creatively to create a spotlight effect when using a normal lens.
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  three group
   
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  Top Off
  Refers to the ability of a rechargeable battery to be plugged into its charger for a brief time to ensure maximum capacity. Older battery technology required that a battery be fully discharged before charging, eliminating the possibility of "topping off." All Quantum batteries may be topped off at any time with no ill effects.
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  Transceiver
  A wireless device that can be used to both transmit and receive wireless signals. Quantum's FreeXwire model FW10W can be used at the camera to trigger a remote flash and it can be used at the flash to receiver trigger and TTL signals from a FreeXwire FW9T at the camera. The FW10W can also trigger a remote camera.
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  Transmitter
  A device that can be used to transmit wireless signals to trigger a remote flash or camera. Quantum's FreeXwire model FW9T can be used at the camera to trigger a remote flash, including sending TTL signals. To complete the package, a compatible FreeXwire - FW7Q or FW8R -receiver is required. An FW9T transmitter will also trigger a remote camera equipped with a Quantum FW8R receiver.
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  TTL
  Refers to the metering system in a camera and stands for Through The Lens. The TTL light-metering sensor that determines proper exposure is within the camera body, and reads the light coming through the lens. Because such a system is "aware" of subtle changes in the final composition, regardless of lens focal length or zoom position, as well as compensating for lens filters and macro work, it generally provides more accurate exposures than a system that uses an external metering system.

While TTL originally referred to ambient-light exposure metering, on modern cameras TTL metering is also used to accurately control flash when a so-called dedicated flash unit is used. Quantum's Dedicated QTTL Adapters transform a Quantum Qflash into a fully dedicated unit that mimics almost all of the features and functions of a camera manufacturer's dedicated flash, while providing more power in a rugged, heavy-duty package.
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  TTL exposure
  Refers to the metering system in a camera and stands for Through The Lens. The TTL light-metering sensor that determines proper exposure is within the camera body, and reads the light coming through the lens. Because such a system is \"aware\" of subtle changes in the final composition, regardless of lens focal length or zoom position, as well as compensating for lens filters and macro work, it generally provides more accurate exposures than a system that uses an external metering system.

While TTL originally referred to ambient-light exposure metering, on modern cameras TTL metering is also used to accurately control flash when a so-called dedicated flash unit is used. Quantum\'s Dedicated QTTL Adapters transform a Quantum Qflash into a fully dedicated unit that mimics almost all of the features and functions of a camera manufacturer\'s dedicated flash, while providing more power in a rugged, heavy-duty package.
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  TTL Flash
  Refers to the metering system in a camera and stands for Through The Lens. The TTL light-metering sensor that determines proper exposure is within the camera body, and reads the light coming through the lens. Because such a system is \"aware\" of subtle changes in the final composition, regardless of lens focal length or zoom position, as well as compensating for lens filters and macro work, it generally provides more accurate exposures than a system that uses an external metering system.

While TTL originally referred to ambient-light exposure metering, on modern cameras TTL metering is also used to accurately control flash when a so-called dedicated flash unit is used. Quantum\'s Dedicated QTTL Adapters transform a Quantum Qflash into a fully dedicated unit that mimics almost all of the features and functions of a camera manufacturer\'s dedicated flash, while providing more power in a rugged, heavy-duty package.
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  TTL Metering
  Refers to the metering system in a camera and stands for Through The Lens. The TTL light-metering sensor that determines proper exposure is within the camera body, and reads the light coming through the lens. Because such a system is \"aware\" of subtle changes in the final composition, regardless of lens focal length or zoom position, as well as compensating for lens filters and macro work, it generally provides more accurate exposures than a system that uses an external metering system.

While TTL originally referred to ambient-light exposure metering, on modern cameras TTL metering is also used to accurately control flash when a so-called dedicated flash unit is used. Quantum\'s Dedicated QTTL Adapters transform a Quantum Qflash into a fully dedicated unit that mimics almost all of the features and functions of a camera manufacturer\'s dedicated flash, while providing more power in a rugged, heavy-duty package.
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  TTL Mode
  Most flash units have a light sensor on the body of the flash which controls exposure, usually called automatic mode. Cameras equipped for dedicated flash exposure also have a light sensor within the camera body, providing Through The Lens flash exposure control (see TTL). Setting the flash to TTL MODE ensures that flash metering is now controlled by the camera, rather than by the sensor on the flash.
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  TTL ratio fill-in flash
  Modify the amount of flash that the camera requests, creating a lighting ratio between ambient light and the fill-in flash.
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  TTL-Ratio
   
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  Turbo
  Quantum's trademark name for it's line of high-voltage, high-capacity, rechargeable external batteries. These rugged batteries power Quantum Qflash and most popular camera manufacturer's and third-party flash. Some Turbo batteries can also power certain digital cameras while simultaneously powering a flash.
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  Turbo Speed
  Turbo batteries are designed to provide power to your flash through it's High Power input. This allows fast recycling, so you never miss a shot.
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  Umbrella
  Built like a traditional rain umbrella, but for photographic purposes made of matte white or satin silver material. By aiming a flash into an umbrella, the entire umbrella surface glows, creating a very large source of soft illumination. Used for portraits and other studio shots. Similar in function to a soft box.
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  Underexposure
  Less light than necessary, which creates an image that looks too dark, too muddy, with no detail in the shadows and dark tones. It may be caused by not waiting for the flash to recharge between shots. Often, underexposure is caused when the flash is farther than the allowed distance when shooting in automatic or TTL mode. For each chosen f/stop, there is a near-to-far-range that will provide proper exposure (the range is indicated on the LCD panel on the flash). Opening the aperture and/or raising the ISO will allow the flash to provide proper exposure at longer distances.
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  Vehicle Charger
  Plugs into the cigarette-lighter outlet on cars and trucks, permits charging of most Quantum batteries while on the road.
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  Watt-Seconds
  A measure of the inherent energy stored in the capacitors of a flash unit. The effective illumination of a scene results from a combination of available watt-seconds, and from the flashtube reflector which determines coverage. Those two factors (plus ISO) determine the Guide Number of the flash. One flash can have a Guide Number higher than another, yet a lower watt-second energy, if it concentrates its energy into a very narrow coverage. The watt-second rating is a more significant whenever bounce or diffuse lighting is employed, since the multiplying effect of a narrow beam angle is negated. Qflash are high watt-second units that accept telephoto to softbox light modifiers for varying light effects and Guide Numbers.
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  Wireless TTL
  The transmission of flash trigger and TTL exposure control signals through the air without wires. Quantum's FreeXwire system provides extreme versatility and great range using radio-frequency signals. Quantum's QNexus wireless system receives infrared TTL commands from certain Nikon and Canon flash units to trigger a Qflash.
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  Zone
  A term used to describe how remote flash units are grouped for wireless control. Quantum\'s FreeXwire system, has four zones. Some flashes can be set to trigger from zone 1, others from zone 2, etc. The zones can be turned on and off from the camera position, providing the photographer great versatility in altering the lighting effect.

In addition, FreeXwire has eight selectable communication frequency channels. Combining these eight choices with the four available zones creates 256 possible combinations for lighting control.
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