A Guide to Buying the Right Digital SLR Camera Flash

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A Guide to Buying the Right Digital SLR Camera Flash

Many digital cameras already have built-in flash units. These are perfectly adequate for general snaps but also have distinct limitations. One of the solutions to this problem is to buy an external (or off camera) flash unit. There are a wide range of units to choose from, at different price points and with varying degrees of technical complexity.

The Downsides of On-Camera Flash

In-built flash units are convenient to use, but they have clear disadvantages when it comes to taking great-quality images. For example, they are more likely to create red-eye in portrait photos. The lighting effects tend to be harsh, and the light source always comes from the direction of the camera. It is difficult to control the intensity of the flash, hard to illuminate large areas effectively and, because it drains a lot of power, on-camera flash also reduces the life of the camera battery.

By contrast, external flash units have their own power supply. They recycle (recharge) faster than on-camera flash, making it easier to take lots of pictures quickly. The position, angle and intensity of the flash can be adjusted to achieve subtle and varied lighting effects. For example, an external flash with a mobile head allows the photographer to bounce light off an external surface and back onto the subject, reducing shadow and softening the overall effect. Most off-camera units also come with automatic or manual modes, so the user can choose to override the default settings in unusual situations or for creative effect.

Choosing an External Flash Unit

There are a wide range of alternatives, from the single external flash to sophisticated three-light set-ups, so focus on a few key questions. Firstly, know what type of photography the unit is going to be used for. Small objects and close-up portraits have different lighting requirements to groups of people in large open spaces. It is helpful to have a specific need in mind.

Secondly, decide on a budget because prices vary enormously: this will automatically narrow the field. In general, cheaper units use a narrow range of automated settings and are the natural choice for the beginner or occasional photographer. More expensive units have better build quality, greater coverage and manual control options, and are better suited to experienced or professional users. Finally, get familiar with the technical jargon. This makes it easier to compare similar units in the same price band.

Understanding Flash Terminology


Guide Number

The maximum permissible distance between the flash and the subject. The higher the guide number, the more powerful the flash unit.



Recycle Rate

How quickly the flash can reach a full charge. A flash unit that recycles quickly is the best choice for taking lots of pictures in quick succession.



Flash Sync Speed

The fastest shutter speed to be used with flash. Flash Sync Speed is a feature of the camera, but the upper speed limit is determined by the choice of flash unit.



Slow Sync Flash

A combination of the flash with slow shutter speeds. Slow Sync Flash, also a feature of the camera, is useful for creating motion blur effects or for increasing the visibility of ambient light to give the background of a picture more depth.




Through the lens (TTL) flash metering sets the correct flash output and exposure according to data from the camera's image sensor.



AF Assist

Gives more accurate autofocus (AF) over longer distances and with less available ambient light.


Different Types of External Flash Units

There are three main types of external flash unit: external flash lights, strobe units, and flash triggers or slave units.

External Flash Lights

The most straightforward way to upgrade a digital camera is to add an external flash light. They are fitted to a connector on the top of the camera called a 'hot shoe' which relays information from the camera to the flash. There are alternative mountings, such as ringflash, twinflash, and hammerhead, which modify the position and evenness of the light source and are adapted for specialist use. For best results, buy a flash made by the same manufacturer as the camera.

External flash lights are relatively inexpensive. They are light, portable, and run on standard AA batteries. They produce more light than an in-built flash, and most support advanced features like bounce and swivel, which allow the photographer to adjust the angle and direction of the light source. An external flash light sits well above the camera lens, so it also reduces red-eye in portrait photography, caused by the light reflecting off the back of the subject's retina.

On the downside, flash lights produce less light than strobes or high-end solutions. For work in poorly-lit environments or where bounce and swivel is necessary, choose units with a higher guide number. The digital camera communicates with the flash unit through the hot shoe connector and automatically adjusts settings like shutter speed and focal length of the lens. Look out for units with automatic and manual modes which enable the user to customise the flash settings. These lights tend to be at the more expensive end of the range but allow the experienced photographer to get optimal flexibility out of the combination of camera and flash.

Strobe Units

Strobe units are not attached to the camera itself. By comparison with an external flash light, they are bulky and heavy and need to be mounted on a separate stand. They also need to be plugged into an external power source or a rechargeable battery pack.

On the plus side, strobes produce a light, more light than a basic flash unit. They also provide the photographer with additional flexibility because they can be bought in packages that include multiple lights, and they are compatible with a range of flash modifiers like umbrellas, soft boxes, and barn doors.

Strobes are particularly well suited to taking high-quality studio-style portraits. On the other hand, because the unit itself isn't very mobile, a strobe isn't a good choice for an action photographer.

Flash Triggers and Slave Units

Flash triggers are devices that relay a signal from a digital camera to the flash unit, telling it to fire. The most common type of flash trigger is the camera's own hot shoe. The disadvantage is that the flash has to be physically connected to the camera. There different types of trigger which allow the flash to be mobile, involving either an extension cord or the PC-Sync port on the camera. The advantage of the PC-Sync trigger is that it allows the camera to be connected to a studio strobe unit as well an external flash light.

Slave units are flashlights designed to supplement the digital camera's onboard flash. They have remote triggering built in and are designed to fire when another flash goes off in the sensor's field of view.

The disadvantage of slave units is that they can be unreliable and are likely to respond to any light going off nearby - not necessarily another camera flash. A more flexible, and expensive, solution is to trigger the slave wirelessly. Wireless triggers send a special signal to the slave flash units telling them to fire each time the camera shutter button is pressed. Wireless triggers can fire multiple flashes from great distances, and some work around corners and through walls. Most importantly, they prevent slaves units going off by accident: the external lights will only respond to the wireless signal.

Flash Modifiers and Attachments

As well as the different types of external flash, there is a range of devices which can be fitted to the flash to modify the intensity and character of the overall lighting effect. These attachments include small plastic diffusers for external flash units, reflective umbrellas and discs, square diffusers for strobe units (softboxes), coloured material (or gels) that fit over the front of the flash head, and tubes and grids that transform the light into a very precise flashlight. Before deciding on a flash unit, it is a good idea to make sure it accepts external attachments that would benefit the preferred style of photography.

Finding Digital SLR Camera Flash on eBay

As the largest online auction site, eBay is an excellent place to look for flash units. If a particular make of flash unit is desired, then it can be searched for using the search bar at the top of every eBay page. To begin, navigate to the eBay homepage. Then open the All Categories tab, and click on the link for Electronics and then the links for Cameras and Photography. From this page, select Flashes and Accessories, then Flashes or Other Flashes and Accessories. From here it is possible to browse through the available item listings. In order to narrow the search down even further, the options at the left hand side of the page can be highlighted.


Flash units are a very cost-effective way of enhancing the capabilities of a digital camera. There is a wide range to choose from, but focusing on a few key questions will narrow the field and ensure the flash is fully compatible with the camera itself. Ultimately it's how the equipment is used, not how much it costs, that determines the quality of the end product.

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