Light is the life of the image, without light we see darkness and when we can’t use natural light, we use artificial light, usually flash, as it too will produce the necessary color, texture, shape and form. While all flash units
produce light, purchasing one should not be like the way we buy new cars today were we don’t even look under the hood anymore—purchasing photographic lighting is a
long-term investment and every purchase should be an
informed decision, not impulse buying.
One word of safety and caution before we proceed with the original gist of this article—flash units when inappropriately used have been linked to cause photosenstive epileptic fits, disorientation and seizures, even with non-epileptic person triggered by visual stimuli, such as flashing lights! Statistics record two people in every 10,000 are photosensitive epileptic. Often people who are susceptible to PSE have no history of seizers or epilepsy, most are under the age of 20. There are actual laws that govern the use of “strobes” in public places as they can produce nausea, vomiting and epilepsy, especially when stobes/flash units used excessively and at an inappropriate rate. In addition, flash circuits use, store and release high voltage that can kill a person instantly. Never touch a flash tube with your bare hands, even if the unit is unplugged. Always discharge your unit by firing the test fire button twice, even then, assume the unit is still charged and deadly.
But before we can purchase any type of light, we must look at light, as light is also
perceived and the light source itself (quality), not the box that houses it, but the actual source, is often overlooked. As an example, not all white-light is white, typical household florescent bulbs produce green-tinted light but the human eye and brain perceive it as white. The same happens with typical household bulbs for tabletop lamps, they normally produce a more warm
tungsten light, or yellow-red-light, again, the human eye and subconscious perceive it as white. This
brief portion of light theory is to illustrate not every “flash tube” in artificial photographic lighting is the same, no more than every household bulb. Lighting varies not only by manufacturer, but by lax or tight manufacturing tolerances and the “guts” inside and out that construct it.
Not all lights are created equal (quality control). Lights vary by the temperature of color they produce, or
Kelvin, and even though the Kelvin scale is large in
gamut, the main Kelvin all photographers should know is 3200K (3200 Kelvin) for tungsten lamps and 5400K (5400 Kelvin) for the ideal flash output. While some photographic flash units will vary from 5,000 to 6,000 Kelvin, 5,200 to 5,400 Kelvin is the
ideal range (less cold-colored) and well-built flash tubes usually sport a 100 to 200K tolerance, even when voltages vary while units are plugged to a household circuit.
Uncoated, less expensive tubes are closer to 5600K.
It’s rarely noted by manufactures and more rampant in non-multi-voltage flash units, as the voltage supplying the electricity to the capacitors change by the second, this can have a
negative impact in final color temperature produced by a flash unit. The voltage supplied to the capacitors in a flash head is more stabilized, or regulated, with higher-end units, especially those that work from 110 to 240 volts, or multi-voltage flash units.
Another factor that can affect flash tube tolerances and temperatures as well are temperature variances in use, along with flash-tube durability over time, is
where the flash tube was manufactured. All flash tubes will eventually fail or run out of gas, sort to speak. The average lifespan of a tube depends on many factors, including the
ambient operational temperature, also affected by the modeling lamp type (wattage), the amount of
flash energy used and how often the flash is triggered in sequence—thus the lifespan of a tube is unpredictable at best.
Many “manufactured in the U.S.A.” flash units are
assembled in America from “foreign” parts and the vendors know they can legally put “manufactured” but not
Made in the U.S.A. under Federal Trade Commission guidelines. So don’t be fooled with “manufactured in the U.S.A” claims—it’s not always 100-percent American as we’re misled to believe, especially when the parts inside might come from places like China, this is not to say they are inferior, just understand there is a difference between
manufactured (assembled) and made in the U.S.A. Some manufactures will
skirt the “Made” by purchasing parts from U.S. distributors, though many internal
capacitors and even the flash tubes they drive are not made in the U.S.A.
Speaking about manufacturing, the way the tube is
sealed can have an impact on the long-term costs of your flash unit, some tubes use epoxy, some a glass-type solder (fused-quartz), some the glass itself to seal the highly-pressurized gases in the tube. Over time heat and other elements, such as banging your equipment around, can cause these tubes to leak as they are under extreme pressure, causing their replacement. Usually the old adage applies here,
you pay for what you get, buy cheap, get cheap tubes.
Ever notice higher-end studio flash units have a glass protective dome over the tube? This is because these higher-end units use higher pressured tubes for more
accurate color temperatures and
shorter flash durations in addition to the fact they can handle higher-power and deliver more
true watt-seconds than those without the covers—the covers are more for safety, as rarely will a high-end tube explode. Some covers will also come in
UV coated and/or color temperature tints for warming of a tube’s Kelvin output.
Higher-end tubes use higher pressurized gas, thicker quartz glass (the tube itself) and are also
coated, usually for UV reduction but more important, for tighter color temperature control.
Inexpensive units use uncoated tubes and cost up to tens times less than better-built tubes. Many semi-pro and amateur photographers are led to believe this is not important, which is another form of marketing hype especially if you photograph people in clothes. Certain clothing or fabrics with synthetics will change colors with uncoated flash tubes and will “fluoresce” with the added UV light produced by uncoated tubes resulting in various color shifts in the final image—not even shooting in “raw” with digital photography can correct this phenomena.
Additionally, uncoated flash tubes will produce a higher blue in the actual color of the flash due to their colder color temperature of 5500K and higher.
The majority of flash tubes for photographic purposes are filled with
xenon gas and discharge at their peak after they are initially
ionized and a high voltage is placed across the tube, which produces a broad spectrum of light that resembles the color temperature of daylight.
While the tubes are just one integral part of a flash unit, there are other internal items, such as capacitors and circuits, all of
equal importance for the overall product, hence why photographic flash units are classified into
good, better and
best categories.
Here is a
sample matrix for the most popular brands in
no specific order:
Best Units:
Hensel
Broncolor
Profoto
Balcar
Briese (consider very top)
Comet
Speedotron (black line)
Better Units:
DynaLite
Calumet
Photogenic
Elinchrom
Visatec
Norman
Bowens
Speedotron (brown line)
Good Units:
Novatron
Alien Bees
Impact
Interfit/Patterson
White-Lighting
Multizblitz
JTL
Britek
SP-Systems
Smith-Victor
Sunpack
Photographers often purchase products on impulse, sometimes because the marketing hyperbole that surrounds those products can cloud their decisions. Photographic lighting is a major investment, just like purchasing a new car, and like purchasing a car, you must look past all the marketing and look under the hood—chances are if it walks and looks like a duck, it’s a duck.
An animation of a Xenon flash lamp being fired. Contributed and licensed under the GFDL by the photographer, Gregory Maxwell Source, Wikipedia
http://en.wikipedia.org/wiki/Xenon_flash_lamp
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