Night photographer Lance Keimig takes you on a journey to the Aurora Borealis and helps you from start to finish, beginning with preparation for cold, Icelandic weather and finishing up with exposure...
This is an attempt to answer (or anticipate) some of the questions that
newcomers to studio lighting often ask. It isn't a technical article as such,
just an introduction that we hope will be helpful to people just starting out in
There are basically two forms of artificial lighting -
continuous and flash.
Continuous lighting can be sub-divided into:
Tungsten - The term includes household lamps, security lights, theatre
lighting and car headlights as well as lights designed specifically for
Metal discharge, e.g. HMI.
Continuous lighting is often seen by beginners as being ideal, possibly
because, in its most basic form it seems to be cheaper, and possibly because of
its WYSIWYG (what you see is what you get) qualities. In fact, although the basic
lights may be cheaper than flash the running costs are higher and the various
light modifiers needed are both more expensive and less efficient than with
Although there are exceptions, most tungsten light designed specifically for
photography produces light of a colour around 3200 - 3400 deg K, which is much
warmer in colour (less blue) than flash. Because of this the colour needs to be
corrected by using filters, either in the form of gels fitted to the lamps
themselves or to the camera lens. However, if the tungsten lights are the ONLY
light source (i.e. all lights produce the same colour of light and there is no
daylight or overhead room lighting) then filters are not needed with digital
cameras, where the white balance can be adjusted instead of using filters.
We were trained on tungsten lighting and I (Garry) still use it today, if only
very occasionally, if I am photographing still life subjects or room interiors
when it's possible to use very long exposures, or when I deliberately want to
include subject blur, for example blurred people in an architectural interior.
But I would never use them for portrait or any other kind of people photography,
for the following reasons, not in any particular order:
Although they appear to be very bright, tungsten lights produce a very
low level of actual light compared to studio flash and so they are less than
ideal if short shutter speeds are needed, or if a small aperture is needed for
depth of field.
They are known (in The States at least) as hotlights, and there is a very
good reason for this - they produce far more heat than light and are both
intimidating and very uncomfortable for the sitter. Think of them in terms of an
electric heater - the function of the heater is to produce heat and it does so by
passing electrical current through a thin wire - as a side effect, some light is
also produced. This applies to tungsten lighting too because although the light
is brighter and whiter there is still a lot more heat than light.
Because of the amount of heat they produce it is difficult and expensive to
fit them with modifiers such as softboxes, they can melt lighting gels and
scrims, polarising gels will be ruined by the heat and the lamps are liable to
'blow' if they are moved or adjusted when they are switched on or still hot.
They present a very real risk of fire.
They use a lot of electricity
They are not adjustable for power - dimmers can be fitted but this is for
setup use only, because the use of a dimmer dramatically affects the colour of
The colour of the light is inconsistent. With all forms of tungsten lighting,
small changes of current will change the power output to some extent and will
change the colour too, sometimes quite dramatically, so you'll get inconsistency
between your shots. Quartz halogen lamps maintain their output power fairly well
throughout their life but 'Photoflood' lamps (basically very short- life overrun
domestic lamps) darken with use and change colour too.
Because the lights appear to be very bright, the pupils of live
subjects are smaller than normal and look decidedly odd - very similar in effect
to bright sunlight.
In theory, if you're shooting on digital then changes of colour or even output
may not seem to be important as long as all of the lights are the same -
but even though nearly all my own shots are on digital I'm old-fashioned enough
to believe that it's much better to get the shot right in camera and to keep
avoidable computer work down to a minimum.
They do have a couple of advantages over studio flash.
They are cheaper, at least initially.
They may be easier than flash for beginners because arguably they show a more
accurate rendition of how the actual shot will look. Budget studio flash units
tend to have pretty weak modelling lamps, which don't give an accurate indication
of how the final shot will look. The reason for this is that although the
modelling lamps contribute little or nothing to the actual shot (and neither does
the ambient light in the studio) because the light is totally overwhelmed by the
power of the flash, the ambient light does affect the photographers'
perception. The ambient light effectively lowers the contrast created by the
modelling lights, so the actual contrast of the shot is much higher than it
appears to be.
All forms of continuous light, unlike flash, can be metered using the camera
exposure meter but this has the disadvantage of measuring the reflected light,
which is usually less precise than measuring with incident light. Continuous
light will also work with any shutter speed as long as the power is sufficient,
and doesn't need to be synchronised to the camera shutter. Other than that, we
can think of no advantages at all.
Professionals have used fluorescent lighting for years and it has also become
almost the standard in TV studios. But let's not get confused here, because
there's a world of difference between the pro fluorescent lighting and the
Flat panel fluorescent lights are available for the amateur market.
These lights are claimed to produce daylight colour, removing the need for colour
correcting filters. In fact, fluorescent light is deficient in magenta and so (on
the lights I've tested) the manufacturers have added a magenta grid. Clever.
Because they are fluorescent and not tungsten lights, they are cool running.
Personally, I do not feel that they can generate anywhere near enough power
for any type of still photography of people, although it seems they're OK for
video photography. I made this observation once before and a manufacturer got a
little bit sniffy about it and told me that I was wrong. I responded by offering
to test their products in my own studio but I heard no more from them...Since
then I've carried out a quick & dirty test on a couple of lights owned by
someone I know - 2 of these flat panel lights, each measuring 17"x13" at a
distance of 72" from the subject. And the result? 100 ISO, 1/30th at f1.5, or 1
sec at f6.3. An incident light measurement with the sensor actually pressed
against the screen, which is useful for measurement but which is not a practical
test, produced a reading of only f22.8 at 1/30th... ! The manufacturers also
claim that they produce soft light. Well, they will produce soft (if uneven)
light at a lamp to subject distance of up to about 21", which produces a 100 ISO
reading of f6.3 at 1/30th sec - so they may be usable for some tabletop still
life applications I suppose. The tests I carried out were on one make of light
only, perhaps there are other, better ones available too, I don't know.
HMI stands for Hydrargyrum Medium-Arc Iodide. Hydrargyrum is better known as
Mercury (Hg) and Iodide indicates that Iodine (a halogen) is used in the
HMI lights are very widely used in the motion film industry - the lights are
massive and very expensive but they are ideal for the purpose because
They have a consistent colour temperature of around 5,600 degrees
They are flicker-free 
They are cool running 
The quantity of light produced is fairly high 
Notes  The colour temperature is OK up to about 500 hours of use, after which
they become progressively more green. There is usually an 'hours run' meter so
that the lamps can be changed when necessary.
 They are available with either magnetic or electronic ballast, electronic is
much more expensive but produces flicker- free, consistent lighting.
 They are not really cool running but are much cooler than their equivalents
in tungsten lighting.
 They are efficient in that they produce a lot more light than their
equivalents in tungsten lighting - this is not an authoritive statement (just my
own finding based on limited personal experience) but a test on one of my own 70
watt HMI lights produced slightly more light than a 500 watt quartz halogen lamp,
PAR (parabolic aluminized reflector) with no modifiers, 1 meter distance from a
standard grey card. The result was 1/250th at f4.8, 100 ISO.
This shot shows, left to right, a 70 watt HMI, a 500 watt Quartz
Halogen and a standard flash head, all positioned 2' from a cream wall. The
aperture of f22 was set to suit the flash, which was dialled down to just 37J,
and the shutter speed of 1/4 sec was set to suit the continuous lighting. As you
can see, the level of light produced by both forms of continuous lighting were
Used in a studio for people photography, HMI lights have basically the same
advantages and the same disadvantages as tungsten lights, except that they don't
run nearly as hot, the colour temperature approximates average daylight and the
colour and output is very consistent. Because they don't run as hot as tungsten
it's much easier to use modifiers such as softboxes, scrims and honeycomb grids,
if they are available in the fittings needed. HMI lights are fairly popular with
still life photographers and there is at least one brand that comes complete with
a very good range of light modifiers specifically designed for very precise still
life photography. The light output is very low however and I can't comment on the
usefulness or otherwise of this particular setup because I have no personal
experience of it. Personally I only use my 2 HMI lights for the occasional
architectural interior, where I need to hide lights to fill in specific areas,
adjusting the effective power by means of the shutter speed.
Firstly, a statement of the obvious: Photographic flash is nothing more than a
brief, intense flash of light used by photographers to illuminate a subject. It
is normally synchronised so that it fires during the brief period of time that
the camera shutter is open. Used in a studio environment in which there is little
existing (ambient) light, the presence of other light is normally insignificant
and will not affect the exposure, so it doesn't really matter whether the shutter
speed is, say, 1/125th or 1/15th sec - all that really matters is that the
shutter is fully open at the time the flash is fired. The effective length of
the exposure is determined by the duration of the flash, not by the shutter speed
of the camera.
However, where there are high levels of ambient light, this needs to be taken
into account when choosing the shutter speed.Given that the process itself is so
simple, it can be confusing for people when they find that there are so many
different brands, models and types of flash available - hopefully this article
will help to address some of this confusion.
There are 2 very different types of flash, the type that fits onto a camera
and the type that's used for studio lighting.
On-camera flash units are clever, and if they're dedicated to the
camera they can communicate with it, focusing the camera even in the dark,
setting themselves to the camera ISO setting, setting the zoom to suit the camera
lens, calculating the exposure adjusting the power output accordingly.
Studio flash units are dumb, and don't have any of these features -
but they're far easier to use in the studio, generally have far more power and
can be used with modifiers.
The terms flash and strobe are interchangeable and don't refer
to any specific type of unit.
There are 2 basic types of studio flash -
Generator (England) also known as Pack & Head (USA) flash
basically consists of a box that sits on the floor (or, with professional units
too heavy to lift, sits on wheels)
Monoblock (England) or Monolight (USA). Everything is contained
in the head.
Generator/Pack and head lights contain all their 'works' in the box,
and a high-voltage cable connects the box to the actual flash head.
Typically, the flash head contains just a flash tube, a modelling lamp and
(usually) a cooling fan. Because the head itself is so simple it is light in
weight and fairly small, so it's less unstable when perched at the top of a
flimsy light stand or on a boom arm. And because the head doesn't include any
complex electronics there is less risk of damage caused by overheating when using
accessories such as honeycomb grids, which restrict ventilation and trap heat. I
once had a mono head, fitted with a honeycomb grid, blow up - I had forgotten to
switch off the modelling lamp! It was both dramatic and expensive, with a loud
bang, a cloud of black acrid smoke and a terrified fashion model....
Most generator packs can power more than one lamphead at a time. If, for
example, the pack generates 2,400 Joules and can power 2 heads, if only 1 head is
fitted then the output is adjustable up to the full 2,400, with 2 heads fitted
the output per head will be divided between them. Some generator packs are
symmetrical, that is the distribution of power between however many heads are
plugged in is equal, other (better) units are asymmetrical, allowing different
heads to be set to different power levels. The adjustment may be infinitely
variable, or the allocation of power may be fixed, or variable to only a limited
degree - you need to check the spec. One of the many advantages of generator
packs is that all the adjustments are carried out on the magic box, so there is
no need to climb a stepladder to switch off a modelling lamp or alter the power.
Some professional generator packs can also be adjusted from the computer. As with
mono lights, some generator packs have infinitely variable (stepless) power
adjustment, allowing literally any level of power to be set, others have simple
'click stop' dials, which are less versatile. In an attempt to make mono heads
easier to adjust, some manufacturers have remote controls available, either
wireless or hard-wired.
Personally, I'm a great believer in redundancy, so I normally have one
generator pack for each light head, which means that I have extra packs available
in case of breakdown - although breakdown is very rare.As you would expect,
generator packs are more expensive than mono heads.
Monolights contain all their 'works' in the actual head, making them
heavy and delicate. Because of their low(er) cost they are usually the tool of
choice for occasional users, but cost saving is the only real advantage I can
The power hype
Flash power is expressed as watt seconds (w/s) or Joules (effectively the same
thing) or as effective watt seconds (IMO meaningless marketing hype) and about
the only indication you can usefully glean from this kind of 'information' is
that a higher figure should indicate the probability of higher power, the actual
figure and the terminology used is less informative and can be downright
misleading. To indicate the scale of the differences, I tested two makes with
identical theoretical ratings, one produced almost twice the actual power of the
If you really want to know how much power a given flash will produce
you need to look through all the manufacturers data and find the guide
number, sometimes hidden away almost out of sight amongst the hype - the
guide number is an indication of actual measured power, not of consumed energy,
and so this information is actually useful.
Suppose, for example, that the guide number is stated to be 110 (feet). In
Europe we measure in metres not feet, so the figures are different but the
results are the same. What the guide number actually means is that if you divide
the distance from flash to subject into the guide number the answer is the
aperture you will use, assuming the use of 100 ISO film. So a flash with a guide
number of 110 (ft) means an aperture of f11 when used at 10 feet.
Simple? Well... actually, no!
First of all you need to know the conditions under which the guide number was
measured - which reflector was fitted to the head at the time? The choice of
reflector makes an enormous difference - IMO manufacturers should conduct their
tests using a standard reflector, but some reflectors can be up to 400% more
efficient than standard reflectors, producing very misleading figures. 'Guide
Number Inflation' seems to be especially common with the type of flashguns that
fit into camera hotshoes, where manufacturers often quote guide numbers tested on
the narrowest possible zoom. Going off at a bit of a tangent, a few years ago I
tested a few hotshoe flashguns and in each case the actual guide number, tested
in my own studio, was inflated by at least 30%. In one case it was inflated by
Here are 3 different flash heads - this one is one is one of the
cheapest available, what you see here isn't normally visible because the
reflector is fixed and built in to the flash and is normally hidden by a
The flash tube itself if tiny, probably about the same size as
fitted to the average accessory flashgun and the mirror-like qualitites of the
reflector exaggerate its performance, producing extremely harsh and barely usable
Next we have an Elinchrom head in a standard reflector, this
produces directional but useful light of good quality.
And finally we have a Stobex flash head, massive by comparison,
this head operates on very high voltage and is housed in a white-painted
reflector that produces directional yet soft light.
This type of flash produces very long flash duration which can be useful
sometimes (more of this later)
And what about the size and decoration of the studio used? If the test was
carried out in a small room with white walls and a low white ceiling then the
figure will be much higher than in a large studio with distant walls and a high
ceiling, which won't bounce light back from their surfaces.
It's probably reasonable to assume that reputable manufacturers will measure
their lights sensibly and fairly and may publish their testing conditions, but it
may not be a good idea to assume that all lights are tested in the same way,
especially those sold on auction sites?
How much power is enough?
This is a question without an answer! Visit any commercial studio and you'll
find a wide range of very powerful lighting. This is often only normally needed
for large sets (usually furniture) shot at small apertures on large cameras. And
because image quality is paramount in commercial work, just about everything is
shot at 100 ISO or less. If you shoot still life at f32 to get maximum depth of
field, or use a 5" x 4" camera at f45 or a 10" x 8" at f90 you will need a LOT
more power than if you use a 35mm at f16 or a cropped-sensor DSLR at f11. But if
you want to shoot portrait heads in a small studio using a small camera and you
want to shoot at f4 to get part of your subject out of focus then very little
power will be needed and too much can be a problem. And if your studio
photography is carried out on an occasional basis then you may find that the
quality loss involved in using, say, 200 or even 400 ISO instead of 100 could be
acceptable to you - a very cheap way of getting more effective power!
I don't really want to feature specific makes of lights but, just as an
example, let's take a look at the power output of Alien Bees, which seem to be
Take their 'entry level' model, the B400, which they claim to be 160 WS. They
say that, using their standard reflector, tested in what seems to me to be a
perfectly reasonable test environment, the guide No. is 118. Now, this is a very
low-powered unit, but 118 means an ISO 100 aperture of f11.8 at 10 feet, which
seems to me to be very usable for most portrait use. Of course, guide numbers are
just that, guides, and will be affected by light modifiers as well as by
reflectors and the environment.
All modifiers will 'reduce' light to some extent (although, in theory, the
light is not so much reduced as spread around by most modifiers) And a medium
softbox might 'eat' perhaps 2 stops of light but, typically, the softbox would be
used very close to the subject, say 2' away, so there will be plenty of power for
most situations, most of the time.
Don't get the idea that low-powered flash will be fine for every type of
studio, with every type of camera and every type of subject - it won't - we just
feel that we need to point out that high power is not always needed and that
there are other, equally important things to consider.
One important feature is the range of adjustment and the way in which
the adjustment is made.
Now, there are some very basic flash heads that don't have any power
adjustment at all, and the only ways in which the power can (effectively) be
adjusted is to move the head closer or further from the subject, or to fit one or
more neutral density gels in front of the light.Moving the flash closer or
further away is no answer at all, because by doing so you will affect the quality
and softness of the light and the size and softness of the shadows.
Next up in terms of sophistication are lamps with 'click stop' adjustment,
e.g. full, half, quarter power etc. These often have a limited range of
adjustment, and a 100% incremental 'click' doesn't allow for fine adjustment, so
it's better if possible to go for infinite, or stepless adjustment, usually
carried out by means of a slider. Typically, flash units with stepless adjustment
will adjust by about 5 stops, a ratio of 32:1, with an even wider adjustment
range possible on some units.
At least as important as the range of adjustment, is the range of
Some of the very cheapest flash units (AKA auction site wonders) have built-in
reflectors and may not take any accessories at all, but the better makes have a
range of different reflectors available, from wideangle to almost parabolic, from
highly reflective to matt surface, and in a range of different sizes. The
reflectors can be used with umbrellas, or they can have a honeycomb grid fitted
into the front of the reflector, or they can be removed to allow the lights to be
used with softboxes, spotlight attachments etc. Softboxes are usually available
from the lamp manufacturers, and come complete with the same fitting as their
reflectors - or you can buy an independent make, together with a speedring that
fits your lamp. This is often the better option.I've noticed a range of small
softboxes sold on American Ebay that have a 'universal' fitting, simply a ring
fitted with thumbscrews. These will fit onto many lights that cannot otherwise be
fitted with softboxes - and at very low prices too! They are also offered for
sale on British Ebay, but at several times the USA price.
Well, recycling speed may be important to you if you shoot fashion or
any other kind of people photography or if, like me, nearly all your work is
commercial, it will be unimportant. The recycling speed is usually quoted in the
spec, but it can be a good idea to take the figure with a small pinch of salt,
allowing perhaps double the quoted time for the flash to reach its full charge.
Going off at a slight tangent, some flash units can be set to beep when ready to
use, with others the modelling lamp switches off when fired, coming back on when
recharging is (claimed to be) complete.
Modeling lamps don't normally contribute to the actual exposure, their
function is simply to indicate the effect of the light. Even the best modelling
lamps fall short of the ideal however, simply because the light isn't bright
enough to show the true contrast that the flashhead produces. As a result,
shadows are always much harsher than the modelling lamp indicates them to be.In
general terms, the brighter the better as far as modelling lamps go; bright lamps
provide more information to the photographer and make focussing easier. Turn the
room lights out and block out any natural daylight to get the most accurate
indication from the modelling lights, especially if you have budget-range lights
with dim modelling lamps.
Some flash heads are fitted with proportional modelling lamps - what
this means is that if the power of the flash is turned down then the brightness
of the modelling lamp is reduced in proportion.
(Nearly) all flash heads have a built-in sensor, allowing the flash to
'see' the flash from another head and fire in perfect synch. On some models this
can be switched off if required.
All flash units need to be synchronised to fire when the shutter is open. The
manufacturers supply PC cords that run between the flash and the camera, most
flash units have a standard jack socket, which is simple and reliable, but some
have their own, very special fitting, for example Bron, Elinchrom and Strobex
each have their own unique fitting. The Bron and Strobex ones are generally
reliable. But whatever the fitting, I strongly advise you to get a radio
transmitter set to trigger your flashes - much more reliable and no danger of
damaging your camera if the trigger voltage of the flash is too high! The leading
brands are Pocket Wizard and Pulsar, but cheapo ones are now available at far
lower prices and most people seem to find them perfectly O.K. for normal home
Another factor is colour shift. Basically, flash heads are supposed to produce
'photographic daylight' colour, usually at around 5,500 deg.K The better makes
hold this colour accuracy regardless of the power setting, but some of the
cheaper makes don't, and the colour can change (usually to a warmer colour) as
the power is reduced.
Another factor that may or may not be important to you is
flash duration - the length of time that the flash actually fires for, and
which determines the length of the exposure.Now, with on-camera flashguns the
duration largely depends on the power setting (because on-camera flashguns
produce a full-power flash but switch it off early when less power is needed) but
studio flash works in a different way. Many studio flash lights have a longer
flash duration when less than full power is used. With some makes of
generator/pack flashes you can have a choice of slow or fast heads.Whether flash
duration matters or not depends on the type of shots you want to produce ? with
still life photography it doesn't usually matter, although it can be
important for shots involving steam, pouring liquids or splashes.
For portrait photography just about any flash duration will be fine, for
fashion photography or for the type of shot below, where fast movement can be
involved, a long duration can cause subject blur, which may or may not be what
Which make and why?
No, I'm not going to recommend any particular manufacturer, instead let's just
recap on the things that should be important to you.
A wide range of adjustment
The ability to change reflectors
The availability of a wide range of well-designed light modifiers (e.g.
softboxes, honeycomb grids, spotlight accessories) (check the fitting - some
cheap makes take the same fitting as expensive pro equipment so they can use top
Easy to adjust
Right, that's ruled out all of the 'auction specials' that I've personally
seen. Now the things that might be important to you
Consistent colour, especially at lower power settings
Short flash duration
The ability to control the flash units from your computer
Weight and portability
Will it stand up to 'all day every day' use?
Will you be able to hire in extra units if needed?
Generally, with lights as with everything else you get what you pay for - but
although it's a false economy to get something that is less than suitable there's
little point in spending hard earned money on top quality pro equipment if you
don't need it. And, as you can see from the list above, different people have
different needs anyway.