How to Buy a Flash for Your Camera

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How to Buy a Flash for Your Camera

There are several situations in which using a flash is useful when photographing; for example, when shooting in the dark, or indoors where light levels may be low, or perhaps to give more colour and definition to an outdoor shot. Nowadays most cameras come with a built-in flash, which is useful because it is always available when needed, useful for snapshots. However, photographers with more advanced cameras often decide to buy an external flash to give them greater flexibility.

Built-In Flash

A built-in flash is usually housed at the top of the camera, which is convenient, but has limited capability. Built-in flashes only point forwards, giving a harsh flat effect to the image and creating hard shadows. They are less powerful, there is no control over the brightness, and the red-eye effect in eyes is a common problem due to the positioning. They are slow to re-charge and also use the camera battery which can drain quickly.

External Electronic Flash Units

External units, sometimes known as flashguns or speedlights, can be either attached to the camera or mounted separately. Using an external flash has many advantages.




Can be altered to create better lighting – may be angled or rotated, or even moved away from the camera (off camera) using leads or a wireless trigger.


More powerful than built-in flash, so can reach greater distances


Has its own batteries, so does not drain the camera battery. Some have additional battery packs


Recharges faster than built-in flash, so it is ready for use more quickly

Different Kinds of Electronic Flashgun Systems

There are three main operating systems for electronic flashguns.


Through The Lens (TTL)

TTL flashguns work in synchronisation with the camera's light meter to calculate the settings needed for optimum results. This means they can be used with interchangeable lenses including telephoto lenses and those with a wide focal length. Different manufacturers adapt the specification, e.g. iTTL or eTTL.

Auto Flash

Some cameras, especially older ones, don't have a compatible TTL function, so an auto flash can be used as an alternative. The flashgun uses its own light meter to calculate the settings needed.


On a manual flashgun all settings must be entered manually. The photographer must do the calculating to match exposure time, shutter speed and ISO. Tables are often fixed to the flash gun itself to facilitate this. A manual flash allows flash power to be adjusted e.g.half or quarter power, which is difficult to achieve when utilising automatic settings. Many professional photographers prefer to use a manual flash as gives them more control.

Other Flash Options

Other flash options include:


Slave flash

Do not operate independently, but link to camera's own internal flash system. Often used for studio work. Can be mounted separately (off camera) e.g. tripod. Multiple units can be linked.

Macro/ring flash

Used in macro photography, or for close-ups e.g. portraits as the user can control the shadow created. A flash ring is mounted at the end of the lens and linked to the trigger mechanism. The ring has several lights which can be used separately or in synchronisation.

Specialist flash

Includes specialist options e.g. high-speed flash.

Different Trigger Mechanisms

External flashguns can be triggered in a variety of ways. The most common are:


Hot-shoe mounting

Connectors on top of the camera allow it to communicate with the flash.

Hot-shoe lead

Allows the flash to be used off cameras while utilising the hot-shoe mounting.

Prontor Compur (PC) sync cord

Links the flash to the PC terminal on the camera.


Trigger the flash remotely, without the need for leads.

Slave trigger

Uses the camera's built-in flash trigger to control remote flashes. Can be linked to multiple units.

External Flash Technical Terms

When considering which flashgun to buy, there are several important terms which need to be understood as they convey important information about the function and capability of the flash.

Technical Terms Relating to the Flashgun


Guide Number (GN)

The distance that can be effectively illuminated by the flash – the higher the GN, the longer the range.

Recycle rate

How quickly the flash re-powers ready to be used again.

Angle of coverage

The angle of shot that can be lit effectively.

Flash output

This does not refer to the brightness of the flash, but the duration of light from the flash, as calculated using the automatic features


Some flashguns put out a pre-flash milliseconds before the flash used for the photo in order to make the necessary calculations. This can sometimes cause the subject to blink, but this can be solved by using an override function, which enables the pre-flash to occur up to several seconds before the shot.
This can cause issues with slave flashes – important to have a unit which fires on second flash not on the pre-flash.

Technical Terms Relating to the Camera


Sync speed

The maximum speed at which the camera can interact with the flash.

Slow sync flash

A function that allows the user to set a slower shutter speed than is usual with flash, to get well-lit subject plus increased background light. Some automatics label this 'night-mode' or 'party mode'.

Different Flash Techniques

Understanding some of the techniques that can be utilised when using an external flashgun will help a buyer to decide which model may be best.


Bounce Flash

A flashgun can be angled to allow the light to bounce off another surface (e.g. the ceiling). This reduces or eliminates hard background shadows and soften the shadows on the subject. It is especially useful in portrait or close-up photos. The angle of the flashgun can vary (e.g. 45 degrees, 90 degrees), each producing a different result. Some flashguns can also be rotated to increase the options further.

Fill Flash

This technique is used to enhance the light available when shooting outdoors in low-light conditions or on a very bright sunny day when the subject is in shadow. Automatic features on a camera may read the amount of ambient light and adjust the settings accordingly, but the fill flash technique can be used to override this, resulting in a well-lit subject.

Front and Back Sync

Front sync sets the flash to fire when the shutter opens, creating a blurred trail in front of the subject. Back sync works in reverse, firing as the shutter closes, which creates a backwards blur effect. These features are especially effective when capturing motion shots.

Other Flash Accessories

There are many other accessories that can be used in conjunction with an external flashgun to extend the options even further. They can either be used as extensions to the bounce capacity, reflecting the light, or the flash can be fired through them to create different effects. These accessories include: reflectors, umbrellas, diffusers, and gels.

Buying a Flashgun

Firstly, consider the kind of photography that will need to be done using the flashgun. For example, will it be mainly portrait photography, studio work, or events (e.g. wedding photography). Perhaps it will be wildlife or action shots? The nature of the photography will have a bearing on the kind of flashgun which is best to purchase.

Next, gain an understanding of all the technical terms and what difference each specification makes to the performance of the flashgun. For example, is recycle speed important for taking several photos in a row, or is a high GN more important for the style of photos to be taken?

It is essential to check that any flashgun purchased is compatible with the camera. If the flashgun is the same brand as the camera, it is likely that they will match, but it is still important to check that the flash will work on the exact camera model. In some cases an adaptor can be bought to allow a flashgun to be fitted.

Next set a suitable budget, and research which flashguns fall within it. Used flashguns will naturally be cheaper than new ones, and this is often a good way to obtain a higher-specification flash at a reasonable price. Compare prices online as prices may vary between retailers, and online prices may be cheaper than retail stores.


Using the correct external electronic flash can transform the quality of photographs and open up a wealth of possibilities for enhancing whatever images are taken. By investing time and effort into understanding how the features work and choosing carefully, photographers will end up owning the ideal flash for their individual needs.

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