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Most digital cameras have a built in flashgun. This is an extremely handy solution for those situations when it is too dark for taking pictures. Convenient as these built in flashguns are, they do have limitations.


One of these limitations is power. In the world of flashguns, power means distance and most internal flashes are only useful up to about about 9-10 feet. If you want to take pictures from any further away than this using flash, you need something more powerful.

Before you can consider getting a more powerful external unit, you need to make sure that your camera has an appropriate socket. There are two types, a small round one (known as a PC socket) or, the more common, hotshoe socket. Both of these do the same job of triggering your flash but the hotshoe also holds your flash in place.


The flash is synchronised with your shutter. This is why these sockets are sometimes referred to as "sync" sockets and the cable that goes between the flash and the camera is called a "sync" lead. Sync is just short for synchronised. On Dslr cameras, this synchronisation will only work up to a certain shutter speed.


The power of a flashgun is given as a "guide number" (GN for short). So, if you're choosing a flashgun for its power, this is the number you need to look for. The bigger the GN, the more powerful the flash is and the further the distance it will cover. Flashguns nowadays have their own automatic exposure system. This means that when you take a picture at less than the maximum distance, the flashgun itself will reduce its power output automatically for this reduced distance, giving you the correct exposure.


If you look at a hotshoe socket from above it will either have just one contact in the centre or several metal contact points. If the latter is the case then you can use a "dedicated" flashgun. These are by far the easiest type to use. This is because they will integrate completely with your camera and work exactly the same way as your built in flash. All the flash settings you have in your camera will work on the external flashgun and all you have to remember to do is switch it on.


Dedicated flashguns are mostly made by the same manufacturer as the camera but some independent flashgun makers supply units that are dedicated to specific models of camera. These are designed to work exactly the same way.


More power is not the only advantage you get from an external flash. Because the light source itself is now further away from the lens, the chance of getting red eye in your shots is greatly reduced. Also, many of the external units allow you to rotate the flash and bounce its light off the ceiling or wall.


This is extremely useful because it allows you to use flash without the associated harsh shadows that are normally produced. You do need a nearby light coloured ceiling or wall to do this but it really transforms the quality of the light you get from a flashgun.


If, for any reason, you are not using a dedicated flashgun, then things are a little more complicated. You will need to adjust some settings in your camera to get the best out of it. Normally, you would adjust both the aperture and the shutter speed to set the exposure. But, when you are using flash, that rule goes out the window. The flash fires so quickly that the shutter speed hardly matters. Except for the limitation mentioned earlier with Dslr cameras.


To use a non-dedicated flash, you first need to find out the ISO number setting on your camera. You then need to estimate the distance to your subject. There will be a place on the flash itself to input your ISO number. If the flash has only one power output available, Then just setting the ISO number will give you the range of distances that it can cover and an aperture (f/no.). Some flashguns have a choice of power outputs. Each one will have its own distance range and its own associated f/no. Select an appropriate distance range and read off the f/no. You need to set this aperture on your camera.


Go into fully manual mode and set the f/no. indicated by your flashgun. For most situations, a shutter speed of around 1/100th of a second will be fine even for Dslrs. The camera's exposure meter will probably tell you that you are going to get a badly underexposed shot. Just ignore this, your camera doesn't know that you're going to use flash.


You might think that because you have to set a specific aperture that you should use aperture priority mode, but don't. If you do that your camera will probably try to set a very slow shutter speed to compensate for the dark conditions. This can give you a shot with camera shake superimposed over the flash exposure.


It is worth remembering that every time you take a picture with flash, you are actually making two exposures at the same time. One is the picture you would have taken if the flash hadn't fired, the other is the exposure created purely by the flash. In the most typical situation of using flash in a dark room, the light from the flash should totally overwhelm the exposure your camera would make without it.


Both exposures are defined by the ISO and aperture, but the camera's exposure is also affected by the shutter speed. If this is slow enough for the camera to have exposed the picture without flash, then you will see both images in the final result.


There are times when this is exactly what you want to do. For example on a shot with a very dark foreground but a brightly lit background. You can use the flash to balance the foreground lighting with that of the background. Some cameras have a specific setting for this, called "slow-sync" or something similar. This works with their built in and dedicated guns. You can do the same thing with non-dedicated guns, but it will take some experimentation.


A more typical example is when using "fill-in" flash. This is where the light from the flash is used just to lighten the shadows of an otherwise normally exposed outdoor shot. In this case the flash exposure needs to be much less than the camera's. Some cameras may have a fixed setting for this whilst others will allow you to adjust the flash exposure independently of the camera's. It depends on your personal taste, but traditionally, a flash exposure setting of minus 2 seems to work quite well.


To do this with a non dedicated gun involves a bit of cheating. Once you have got the "correct" aperture from the flash, you then set a smaller aperture than this (higher f/no.) on the camera and use aperture priority so the camera will still give you the correct exposure.


Many people are put off using flash because of the results they see from the camera's built in flash. Which is a pity really, because flash is probably the most useful and versatile light source available to the photographer. On the surface, an external flashgun just gives you a more powerful flash, but in reality it gives you a great deal more creative control over your photographs.


If you would like to discover what an external flashgun can do for you, why not take a look at the extensive range available from They have many models to suit most makes of camera, use the form on their flashguns page to find the right one for you.


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Photographic accessories - flash