At 3:21 AM +0100 2/13/04, Listar wrote:
>Date: Thu, 12 Feb 2004 11:29:33 -0500
>From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxx>
>Subject: [OM] [OT] Any experience with Alien Bees studio flash units
>
>See: <http://alienbees.com/index2.htm> and favorable review here:
><http://davidweikel.com/E20_Page/alienbees/bees.shtml>
>
>I am seriously considering buying some of these. They seem to be
>competitively priced and, although they are monolights, they are
>actually less weight than some lights with separate power supply.
>
>They also recharge incredibly fast. The mid-range B-800 which I am
>considering recharges in 1 second. But in the process, it and the
>others all draw an average of 8 amps for the recharge period. Anyone
>had any problem with this using 3 or 4 flashes. The company's FAQ says:
>
>"The current draw during recycle for an AlienBees flash unit is
>approximately 8 amps. Since the recycle period draws the most amps, and
>this is only momentary, two units will not blow a standard 15 amp
>household breaker. Typically, three, or even four units can be operated
>from a household circuit without problems unless they are flashed almost
>continuously for extended periods of time. Your power cord must be
>connected to a 3-wire grounded outlet, and it is best, for the purpose
>of safety, to use a power strip/surge protector when powering multiple
>units.
>
>Comments?
AlienBees is a division of Paul C Buff, Inc, which makes (made?) the White
Lightning and Ultra monoblock studio flashes.
I have a White Lightning 10000 (Buff's first photoflash, bought in 1985, since
given to my kid sister) and a pair of Ultra 1800 units (bought perhaps 5 years
later). They work exactly as advertised, and have been quite satisfactory.
There really is a Paul C. Buff, and I talked to him on the phone a number of
times in the late 1980s. The key to his then new photo business was the
realization that the traditional photoflash makers had allowed the economic
efficiency (photons per dollar) of their products to decline badly, so he took
a standard photoflash circuit and tuned it for peak efficiency. (The circuits
are all in Edgerton's book "Electronic Flash, Strobe" (2nd edition, MIT Press,
1979). Harold Edgerton invented the electronic flash in the 1920s.) I no
longer recall the details of this tuning, but there was no magic to it. The
magic was the realization that it was worthwhile to do; he has made a fortune
on that realization.
At the time, Paul was trying to find an good way to compare his new flashes to
those of competing units, and the traditional measures of watt-seconds and BCP
(Beam Candle Power) didn't allow one to determine the actual optical output.
Watt-seconds (aka, Joules) tell only how much electrical energy is stored in
the flash capacitor, but does not tell how efficiently this is converted into
light.
BCP tells one mainly how sharply focused the beam is, as the measurement is
made with lightmeter looking directly at the flash unit right on the optical
axis. The problem is that it's too easy to cheat, to use a beam so sharply
focused that standard photo frames will not be filled, giving a false
impression of the optical performance of the flash. And, most flashes shoot
into umbrellas or softboxes anyway.
My contribution was to suggest use of lumen-seconds, which is the international
standard unit of measure of total optical output. (Think of a lumen as a flow
rate in photons per second, and a lumen-second as the total count of photons, a
gallon of photons.) One measures this by shooting the flash into an
integrating sphere and measuring the total light coming out of some other port
in the sphere. An integrating sphere (which need not be exactly a sphere) is a
sphere that is painted white on the inside, with a number of holes (ports)
through which one sends light in or out. The benefit is that the sphere
becomes uniformly illuminated inside, regardless of the exact shape of input
light beam, and the acceptance pattern of the light detector becomes irrelevant
as well.
Shooting into the sphere eliminates the effect of the reflector, if any, and of
the detector acceptance angle, and tells one just how much light there is to
fill the umbrella or softbox.
My own "integrating sphere" is a big cardboard box painted white on the inside,
with a baffle so no light can get directly from flash to flashmeter, all light
must bounce at least once.
The most powerful units are the better deal, and more flexible as one can dial
the power down when needed. The more light one has, the easier things become,
and one can spend more time on the artistic aspects and less time fiddling with
equipment.
Joe Gwinn
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