I am new to the list and hope that this is the correct place
to post this question. I am working for a photographer and
am trying to get lighting set up for his studio, and on-site
locations. My question is what is the smallest generator that
can be used for still photos? Do we need to look at amps or
wattage? I am a newbie at this, so please bear with me.
Tom Bridges Photography
>My question is what is the smallest
generator that can be used for still >photos? Do we need to
look at amps or wattage?
Welcome to the list!
The most important thing to remember when considering lighting
or electrical needs is West Virginia! That is... it's an easy
way to remember the basic electrical formula Watts=Volts x
Amps or W=VA. West Virginia get it. I know it sounds silly
but it is a godsend when you need to do quick electrical calculations.
What you do is figure that every 1000 watt light at 120 volts
will draw 8.3 amps in US electrical systems. Or another way
to look at it is that 8.3 amps are needed for a 1000 watt
light in 120 volt systems. The same formula works with any
voltage (in other countries) just adjust the numbers.
To figure out your needs for a generator you must figure out
how many lights at what wattages and add them up. Remember
that when looking at portable generators the specs are usually
in watts. Larger commercial generators used on film sets are
more often rated in amps.
Look at the generator specs and see how it is set up. Most
are setup for single phase systems which means that a 4000
watt generator will have 2 x 2000 watt circuits. This is important
when considering what lights you will use on the generator
and what plugs will work with the generator.
Another consideration is that the calculation I provided is
for use with tungsten or incandescent lights ONLY. Not for
HMI's or other discharge lamps like florescent which have
their own specific specs of amperage and voltage needs. You
must look into that as well if you have needs for those type
of lights. Most HMI's over 1200 watts use 220/240 volt power.
This will require you to use specifically wired generators
to be able to match your plug needs. Under 1200 watt HMI's
will use a standard Edison plug which is typically provided
on small generators. All HMI's use more amperage on start
up and this can bog down a generator is you are near maxing
out it's amperage rating.
The other major consideration for HMI or discharge use is
to have a generator with crystal synch to maintain the generator
speed to produce 60 Hz (cycles/second) in the US at 24 fps
or any HMI windows. There is the ability to use a non-synch
generator but then the HMI's or discharge lights MUST BE FLICKER
FREE. And the generator must be relatively stable. It gets
tricky using a generator with any HMI discharge lights so
user beware! Best to hire a good qualified film electrician
for those needs to avoid film
flicker problems and such.
In most electrical situations it is best to give yourself
a 10-15 % headroom in ratings. A 2000 watt generator will
be max'd out using 2 x 1000 watt lights on it. Get the next
higher Geni so you have some headroom in the wattage ratings.
Things will run better and smoother with less heat problems
overall on the generator.