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How should you choose an external flash for a camera?

When it comes to necessary photography equipment, flash is not always the first thing you think about instinctively. However, it contributes to the success of photos in many ways and not only when used at night. As we will discover together, using flash creates an artificial light, thereby making it possible to take a photo with extra luminosity.

First of all, we will briefly summarize what a flash is and what it is made of. Then, we will be able to compare different flashes in order to select the one that best suits the photographer’s needs. The models differ according to their uses and the device receiving it. Then, we will be able to establish an initial overview serving as a basic guide according to the use we wish to make of a flash.

Table of contents

The principle of a camera flash

The purpose of using a flash is to create a short, but high-powered light to illuminate a scene in which there is no or insufficient natural light. However, the light intensity (calculated in TTL) must be high (whereas only the camera’s battery provides the necessary energy). This is why a flash is called a “flash”: it’s a fast flash of light intense enough to create the desired instant lighting.

Technically, a capacitor charges itself from the electricity of the battery and then promptly “empties” into a transparent flashtube that delivers the light intensity into the environment of the scene.

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Compare the different types of flashes

One flash is not necessarily worth another, although light is always light. But the flashes can be differentiated by several characteristics.

Measurement of power

The power of a camera flash is determined according to several criteria:

  • ISO sensitivity;
  • light intensity expressed in TTL;
  • the position of the flash zoom (possibility to synchronize with the zoom focal length);
  • the guide number (a number equal to the distance multiplied by the focal length), the larger the number the more powerful the flash.


Therefore, the light output of a flash can be broken down into several measurements allowing you to select one flash over another according to your needs.

Recycle time

Although rarely deciding to choose a flash, the recycle time indicates the minimum technical time between two flashes. Often varying between 1/2 second and 7 seconds, it should not be forgotten that the higher the recharging speed of the flash, the more often it can be used over a given period of time. However, pay attention to the battery life of the camera. A model with a rechargeable battery (Godox type) can satisfy regular flash users.

The different flash models

There are a few typical models of flashes depending on the way they are positioned in relation to the camera.

  1. The Cobra report flash or flash is usually positioned on the top of the camera. Synchronization is achieved thanks to the compatibility between the flash and the device.
  2. The studio flash is usually plugged into the mains or generator and allows a high flash rate for unmatched light quality.
  3. The ring flash is a flash located on the front of the device. Its mode of operation based on low-power light is intended more for macro subjects or portraits.
  4. The camera’s built-in flash is more limited. However, it is generally sufficient for portraits and also allows the triggering of other flashes (for example, wireless mode).


Variants exist in the middle of these four large families, and each manufacturer (Canon Speedlite, Nikon, Sony, etc.) competes with ingenuity to allow the evolution of the range of flashes of cameras.

The other criteria to be taken into account

Obviously, there are plenty of other features specific to flashes as well as elements that make it possible to choose well. These include, but are not limited to:

  • an adjustable head allowing to change the angle according to the scenes to be photographed;
  • the presence of internal and external diffusers (to cover extreme focal lengths and to cover the “flash effect”);
  • a manual flash trigger for testing, open-flash, or triggering other connected flashes.
  • etc.


Not all of them are essential, but it is up to each photographer to determine their needs in order to choose their best photo flash.

How to use an external flash

The external flash has several operating parameters to meet various needs. Without being able to review them all, let’s discover together the most important ones and what they correspond to:

  • TTL mode is a mode that requires the device to measure the intensity of the flash through the lens accurately and taking into account the filters placed on the lens;
  • mode A as “automatic” measures the light intensity on the flash directly and does not take into account the lens filters. This mode is replaced by TTL mode;
  • M mode for “manual” allows the photographer to manage their own flash (open flash) as well as the light intensity;
  • Wireless mode allows you to connect and control other flashes through the main flash;
  • “Video” or “LED” mode allows a less intense but continuous light for making videos (without the quality of “studio” lighting for videos);
  • Stroboscopic mode is a feature that allows you to emit several flashes of light in one second. It is mainly used for specific subjects and is therefore intended for informed users;
  • etc.


Once again, manufacturers (Canon, Nikon, Sony, etc.) are redoubling their ingenuity to make it easier for beginners to learn how to use external flashes while allowing more experienced users to make the most of their capabilities.

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The synchronization of an external flash: an important point

Synchronizing the flash with the camera remains an important consideration. Indeed, if the flash occurs before or after the opening of the aperture, it will have been useless. Therefore, the flash must produce its flash at the right time. But what is the right time? Because as soon as we talk about light, we talk in nanoseconds of light propagation while the speed of opening/closing of the shutter is in hundredths of a second, the notion of the right moment constitutes a dilemma.

It is therefore an important criterion that the photographer must know how to master. In the beginning, the automatic mode allows an optimal trigger for a simple photo. But when effects are sought, the situation is different:

  • long exposure for ambient light;
  • first or second curtain synchronization;
  • high-speed synchronization;
  • etc.


To conclude, the choice of an external flash must force you to ask yourself the right questions. Each photographer (beginner, experienced amateur, professional) will make a different choice among the many options and variants. But most entry-level flashes already offer a number of options that a beginner will take some time to master.

Moreover, the budget to be spent on such equipment is not trivial and it is important to be well informed before making the purchase. Consideration should also be given to ensuring compatibility between the external flash and the camera that will receive it. Then, only practice combined with systematic learning will allow better control of the external flash and the camera.

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