principle. They chose to shoot only using natural light.
Professional photography is also about light and an external flash used
well is an essential part of their arsenal. Some use a few external
flashes to create studio-quality lighting setups on location. Others use
flash to soften shadows or to create interesting light in poor situatuions.
I admit I tend to shoot without flash most of the time. Natural light is
usually the best. Live music photography demands shooting without flash
to catch the interesting colours and the venue lighting's effect. There
are venues when even fast lenses and high ISOs aren't enough but the
photographer still needs to get the shot so flash is the only option.
Flash light can also be used creatively. One of the effects I
experimented is in the mode of light painting but uses tricks with the
lens. Using an external flash and a slow shutter speed I can create a
zoom blur effect by carefully zooming the lens while the shutter is
open. I went a bit further and tried rotating the camera while zooming
with the shutter open which produced highly unpredictable but
interesting and unusual results.
On a practical level an external flash is essential because most of the
photos required for paid work need well lit faces in difficult lighting
conditions. They can be wedding shots or corporate events. They all need
sharp shots. There's scope for artistic shots too but there's what the
customer expects which needs to be delivered upon. Sports and
photojournalism also require a flash. A flash bathes the subject in
light and ensures enough light to use lower ISO settings.
For commercial photography a flash is a must. There are a few options.
As always the manufacturer own-brand offers the best option. A Canon
580EX MkI, a flash I've owned, is very useful. It's powerful and can
zoom the flash in sync with the focal length of the lens. It connects
with the camera metering systems to offer superb flash metering accuracy
in the right hands.
The key advantage of any external flash is the tilt and swivel
capability. This allows the photographer to bounce the flash of other
surfaces. Direct flash is why flash photography gets a bad name. It
doesn't look right. Indirect flash, for example bounced off the ceiling,
can give a soft quality to the light. There are tricks to it, for
example recognising the colour and texture of the surface which is used
to bounce. Dark surfaces eat flash light.
When using direct flash external flashguns have an advantage over camera
flashes because they have larger flash areas further away from the lens.
The distance from the lens reduces the problem of red eye and the larger
area for the flash offers smoother light. There are many aftermarket
flash adapter devices which can soften the light even further, for
example portable softboxes for off-camera flashes.
A major advantage of an external flash is power and, for professionals,
fast recycle time. Power means a flash can reach half way across a
football pitch with a good lens and a moderate ISO. It means high
ceilings can be used to bounce the flash light or dark surfaces can
still be used to reflect flash light. Recycle time means the time
between flashes. The recycle time is important whether using fill in
flash during the day and rapidly shooting to ensure the perfect
expression or moment is captured or shooting live action sports and
needing that fast flash keeping up with the camera's fast shooting speed.
Some flashes feature a very useful ability - high shutter speed
synchronisation. This is usually only available on manufacturer branded
flashes, i.e. only Canon flashes on Canon cameras have this feature.
There is one exception from the independent manufacturer Metz and this
was released a few years ago so more independent manufacturer flashes
may have this capability too but it is standard with the own brand flashes.
All cameras have a maximum flash shutter speed. This is in the region of
1/200s and above on modern cameras. It sounds pretty high but modern
cameras have shutter speeds in excess of 1/8000s. To get these
ultra-high shutter speeds the shutter operates a different way.
Essentially rather than a single shutter moving across the film plane
the camera creates a window moving across. This window moves quickly but
flash light happens in the region of 1/50,000s and faster so only a
small part of the frame exposed by the moving window shutter will be
exposed by the flash.
The high speed sync system fires the flash repeatedly very quickly to
ensure the moving window is exposed evenly as it moves across the
film/sensor plane. It relies on the cmaera and the flash electronics
talking to each other. I think there was the problem that camera
manufacturers charge a lot to get the specification of the communication
system. The independent manufacturers reverse engineer the signals but
can't work out what the internal system is so when camera manufacturers
change it the advanced features stop working. Metz have overcome this
with a flash gun which can connect to a computer if the
software/electronics needs to be upgraded. It uses an EEPROM or an FPGA
or something so when the brand communication system is updated it can be
updated too.
As always price is a large factor in any buying process. I bought the
Canon 580EX MkI in a shop for about £350 a few years ago. It's a very
good flash. It has all the features and it's also very easy to use in
real world conditions. The minor problem with it is weakness in
construction and It broke at one point. Luckily the extended warranty
paid for a replacement. The 580EX Mk II is an excellent flash with all
the bells and whistles but it's very expensive.
The 4xxEX series offer many of the benefits with lower power and recycle
time. Offerings from Metz also compete because they offer all the
features of a Canon-brand flash. Some of their older designs and those
of Sigma don't offer high speed flash synchronisation. This may seem
like a minor problem but it's big one for commercial photography. There
are days when the sun is very bright so fill-in flash is essential to
reduce the harsh shadows. For portraits a wide aperture may still be
desirable to put the background out of focus but this is unattainable
even at the slowest ISO because the of the limited shutter speed without
high speed synchronisation. This is probably the only use I can think
of: soften shadows on bright days. It's useful for sports as well as
weddings and outdoor portraits. It means full control of aperture and
light is possible.
The Sigma flashes are considerably cheaper than the Canon ones. Their
flashes can compete with Canon's flagship in most aspect for the price
of a mid-range model like a 4xxEZ-series flash. They lack that one
quality of being able to be used in any lighting conditions. That's it.
The value of this is quite high though for photographers who know how to
use fill in flash to make take shots and how flash is useful for certain
applications.
For some people a cheap Sigma flash would offer a signifcant benefit to
their photography. The option to bounce the flash off surfaces makes for
much better flash light. It can also be used with much more creativity
than the flash units built into cameras. They offer a lot of value.
The one thing they don't offer is what the pros want. The little things
like recycle time make a difference. The better controls on the 580EX
make it a pleasure to use. The possibility to use the flash in all
situations where it might be needed means high speed flash sync is very
important and worth the premium. Metz now provide an alternative which
has better build quality too. There will be fewer available on Ebay than
the Canons. The professional models also offer other options, ones which
I've rarely used, such as stroboscopic flash. For creative photographers
these features offer new opportunities to experiment.
Further information on this extensive webpage
http://photonotes.org/articles/eos-flash/#controlling
And part 2
http://photonotes.org/articles/eos-flash/index2.html
Some information on Canon's range
http://en.wikipedia.org/wiki/Canon_EOS_flash_system#Speedlite_products
The cheapest alternative from Metz with high shutter speed synchronisation
http://www.metz.de/en/photo-electronics/product-families/system-flash-units/mecablitz-50-af-1-digital/product-information.html
New ones with high speed sync
http://www.dpreview.com/news/1008/10082005metz58af250af1.asp
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