The Comprehensive Camera Flash Buying Guide

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The Comprehensive Camera Flash Buying Guide

Even the cheapest external camera flash will be an improvement over the on board unit supplied with most cameras. The extra power and aim of an external flash can dramatically improve the quality of the images taken.
The differences between modern camera flash apparatus can sometimes be confusing. Manufacturers tend to all use their own different acronyms for denoting the same feature. However, a little research into current camera flash technology can greatly ease the task of choosing the right device.

The Requirement for an Additional Flash

An external flash will offer the photographer not just significantly more lighting power, but also the ability to direct where the light is sent. When used in isolation, light from an on board camera flash can create images that are lacking in subtlety. This is because the light travels directly from the camera flash to the subject and then back again, which results in overly harsh shadows. Bouncing an additional flash from another object has the effect of softening the light and reducing the depth of the shadows. The result of this is a more natural looking image, with finer detail and subtler tones.

Understanding the Guide Number

The most important piece of camera flash terminology to understand is the guide number, or GN value. The guide number is the maximum amount of illumination the flash can provide. It is important to know the guide number of a camera flash unit in order to correctly set the lens aperture. The relationship between guide number and aperture is expressed by the simple formula:
Guide Number = Aperture x Distance to Subject.
With experience, a photographer will usually develop a feel for when departing from this formula will result in a better shot. However, for the purposes of buying an external camera flash, its importance is in allowing the power of different devices to be compared.

Desirable Camera Flash Features

When buying a camera flash, the main aim should be to get the maximum illumination possible for the available money. It can be a good idea to short list those devices which offer the highest guide numbers within the given budget. After this, there are several other considerations which are detailed below:


Recycling Rate

The recycling rate is the minimum time between pops that a particular flash device is capable of, with a fresh set of batteries.
Manufacturers normally give two measurements of recycling rate. The first is the time between flashes on the minimum power setting. The second is the time between flashes when the device is on the maximum power setting. The latter is the more important when comparing camera flashes, with the most desirable device having the highest figure.
It is worth remembering that it will require a set of fresh, top-quality batteries designed for high-drain devices to realise the manufacturers claimed recycling rate.

Automatic Focus Assist

When a modern camera is in auto focus mode, it reflects a beam of red light off the subject to measure how far away it is. Many external flashes have the facility to exploit their extra power to provide a brighter target for the camera's auto focus sensors.
There is a fair amount of variation in the effectiveness of the light patterns offered by external flash units. Patterns with crossed lines seem to offer superior performance to those which use a single line or point of light.

Through the Lens (TTL) Metering

Modern external camera flashes use a rapid series of light bursts to calculate the required flash exposure. This happens in the moment between the camera button being pressed and the camera operating the shutter. The photographer does not need to be concerned with the complex TTL calculation required. The flash and camera together analyse the light bursts, together with the current camera settings, and automatically determine which is the correct flash power setting to use.

Range of Mobility

Most external camera flashes allow the flash head to be moved up and down. This allows light to be bounced off ceilings to produce a more softly lit image. However, some flash units also allow the flash head to be rotated to either side. This allows the photographer a greater degree of control in how the subject is lit. Therefore, it is always worth giving preference to those devices which offer mobility in more than one place.

Automatic Flash Zoom

As the lens of the camera is zoomed in, some flash devices will also adjust their pattern of light to become more focussed. Concentrating the maximum light possible into the image ensures the most efficient use of the power source. Although this is a very useful feature, it is also worth checking that it can be disabled should a different lighting effect be desired.

Wireless Control

If required, the camera's built in flash can be used to wirelessly trigger additional external flashlight devices. TTL metering information is transmitted from the master flash to all the other devices, which are referred to as slaves. While the majority of external flashes can be used as slaves, it is usually only the more expensive devices which can be employed in the role of master. Prior to purchase, it is therefore worth deciding whether triggering addition external flashes is likely to be a requirement.

Flash Special Effects

Two useful features to look out for are rear curtain synchronisation and strobe mode.
When a flash is set to rear curtain synch mode, it only fires the flash just as the shutter is closing. The effect is useful for creating trails, which trace the movements of a subject in motion.
In strobe mode the flash will fire a specified number of times while the camera shutter is open, superimposing several impressions of a moving subject onto the same image.

External Power Facility

Some models of flash allow larger capacity external battery packs to be connected. These can dramatically improve recycling time, as well as significantly increasing the time the flash can be used on one charge.

Additional Considerations

The decision of which external flash to buy will largely be to get the most powerful unit, with the most useful features that the budget permits. However, there are a few other points that are worth considering.

Original Equipment or Aftermarket?

Buying one of the external flashes offered by the camera's manufacturer has the advantage of known build quality and ensured compatibility. However, with this peace of mind often comes a substantially higher price tag.
Many aftermarket products are little more than copies of the branded devices. The build quality of the best of these can be on a par with their more expensive counterparts. Aftermarket models sometimes offer a higher spec or additional functionality, which can make them the better buy. When comparing camera accessories, it is therefore worth giving due consideration to products from all manufacturers.

Used or New?

Camera flashes are complex devices that are easily broken and hard to repair. However, it is easy to check whether a camera flash is in good working order. If considering a used device, ensure that all the various features are able to perform their correct function. Ideally this should be done by the purchaser, but if this is not possible, they should request the seller thoroughly checks the unit on their behalf.

How to Find a Camera Flash on eBay

To find a camera flash on eBay, click on All Categories, select Cameras & Photography and click the search button. Next, select Flashes & Accessories and then Flashes from the Categories section on the left of the page.
The options on the left hand panel can be used to narrow the search to individual products. For example, using these it is possible to display only new Canon shoe mount camera flash devices.
Alternatively, it is possible to search for a specific camera flash using the make and model number. For example, to display all the Canon 430EX flash units for sale on eBay, simply type this into the search bar at the top of any eBay page.


Buying an external camera flash can be an easy and relatively inexpensive route to getting more professional results. The most important consideration should be getting the most powerful flash that the budget will allow. It can be a good idea to draw up a list of the most useful features mentioned above and then prioritise these. Comparing this list with the specs of the devices on offer should allow the purchaser to quickly identify the most suitable flash. Where the budget is more limited, it can be worth giving serious consideration to both aftermarket and used flash devices.

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