Personally, I prefer to use existing light as much as possible, hence the late additional of this posting. But sometimes you have little alternative.
There are basically three types of flash:
- Built in Flash
- Accessory flash units / guns
- Studio Flash
Built In Flash
The built in flash unit on a camera are very limited, usually with a guide number of about 10 – 13, at ISO 100. Although not very powerful the main advantage is that these are always available, being built into the camera and can be very useful for fill in flash.
Accessory Flash Units / Guns
These units offer far more power than built in flash units, and lots more options.
Above is one of my flash units, which has a bounce and pan head, which allows me to bounce the flash of ceilings and walls, which diffuses the light that illuminates the subject, although care has to be taken as sometimes the colour of the ceiling or wall, if a particularly strong colour, can leave a slight colour cast on the photograph.
My flash unit also has a zoom function that can concentrate the flash into the centre of the photograph, to match the focal length of you lens, or zoom setting, which is handy when you are limited how close to the subject that you can get.
Some flash units also have diffusers built in to the head to diffuse the light without having to bounce the light, removing the harsh flash that can sometimes ruin a photograph.
You may have noticed the Velcro pads on the side of the flash head, these were for a flash diffuser which fitted to the head of the flash unit, which was then angled up and the flash was bounced using this diffuser towards the subject. Yes another of my gizmos !
You can use these flash units either fitted on top of the camera, using the hot shoe adaptor, or off the camera on a tripod, controlled via slave sensor:
As shown above, or wireless / infra red trigger. Also flash sync cables can be used, but care must be taken to prevent accidents from people tripping over, or even you pulling over the tripod, with its flash unit, if you walk off too far for the cable to reach.
In fact I have three Pentax Xtra Flash units, which are small self contained slave / flash units which I got for £5.00 each. They work off one AA battery, so they would hardly break the bank for consumables. These units do take some getting used to, but are something that, if carried in your camera bag, could make the difference between a good photograph and a badly lit one.
Looking today, they are not available from this shop anymore, and one price I did find for these units was £19.99 !
The power of a flash unit is shown as it’s guide number, which shows how far the flash would be useful, based on using ISO 100 sensitivity (or film) in meters. But this distance does not take in to account the use of bounce flash, so you would have to consider this when deciding if to bounce the flash off a ceiling or wall.
Studio Flash
These are the big daddy of the photographic lighting world, and are rarely seen outside a photographic studio, due to their size and their power requirements, so when I had a chance, on my last photographic course, to use them I jumped at the opportunity.
The heads to these units, shown below, can be fitted with a number of flash modifiers, for example soft boxes (as shown above (right)), umbrellas (as shown above (left)), snoots and barn doors. These are used to soften, diffuse, direct and control the light from the flash to the subject.
These units are usually triggered via wireless or infra red, or sync cables, but again care has to be taken to avoid accidents.
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