What is Flash Photography

Flash photography is a misunderstood discipline that many of you find very difficult to grasp.

I will try to reconcile you with the flash which may seem difficult to master for some.

With the exceptional sensitivity of today’s cameras, we might ask ourselves why use a flash.

Be aware that in some circumstances, you simply will not have a choice.

When light is scarce, the addition of an artificial light source is a must.

The flash can be used in many different ways and can even become your main tool for photographic work.

This subject is so vast that I won’t go into all the advanced techniques of flash.

In these next lines, I will simply explain the basics of flash photography so that at the end of this article, you will be able to know how to photograph with a flash easily.


Understanding the power of light

In order to better understand how light reacts according to the distance between the light source(s) and the subject, we must look at a fundamental rule; that of the inverse square law.

According to the latter, the power of the light source is inversely proportional to the square of the distance.

Let’s take an example: I place my light source at maximum power one metre away from my subject.

Now, I’m doubling that distance to two meters.

How much light do you think will reach my subject? Logic would dictate that half the power should reach it.

Bad luck, it doesn’t work that way.

This is where the inverse square law of distance comes into play.

Following this law, the power of the light source will be inversely proportional to the square of the distance.

Let’s take the above example again, the distance we doubled is two meters.

To know the amount of light that will reach our subject, we need to calculate its square, which is four.

The reverse will therefore be a quarter of the original power and not half as logic would have it.

In other words, if you double the Flash/Subject distance, you’ll have to quadruple the power.

Flash Exposure

The classic problem that many beginners encounter is to have a well-lit subject, even too brightly lit but with a dark background.

This is not a problem in itself, but a parameter not assimilated by the novice photographer.

Note that the exposure settings for daylight exposures are the same as for flash exposures, with the exception of one, speed.

For simplicity and to allow you to quickly advance your understanding of flash exposure, it is imperative to know and especially to remember the following rules.

The aperture is used to control the amount of flash required to illuminate a subject.

It also plays on the general exposure of the image.

The distance between the flash and the subject controls the amount of light falling on the subject.

Sensitivity increases the flash output and the overall image exposure.

I advises you to keep the values low when using a flash.

The flash shutter speed sets how long the ambient light will be present.

in the photo, and only this one.

It is with this last rule that you must give your full attention.

It will allow you to mix the ambient light with the flash light for a natural look.

Simply put, the lower the speed, the more light is visible in the image.

Be careful, I say it again and again, it does not influence the flash exposure in any way

Best Settings for Flash Photography

If you want to understand how the light reacts, the best way is to switch to manual mode on your camera.

I can already hear some people yelling that it’s a bad idea to start with flash.

It’s not an obligation, but for my part, I started this way and I still work like this.

I learned very quickly how to use a flash in manual mode to see for myself how the light reacts.

The main advantage of this mode is to have control over all parameters.

If you have followed the rules above, you will see that it is not very complicated.

Of course, you can switch to automatic mode, but I do not recommend it, because you will not be able to control the light as you want.

However, you can choose to work in aperture priority mode, which will allow you to control the power of the flash and choose the depth of field.

The shutter speed will then be automatically changed according to the brightness to get the correct exposure, but not necessarily the one you want.

This means that you will not have total control over the ambient light.

TTL mode on the flash

This is an automatic light measurement mode that is calculated through the lens.

So when this mode is activated, it allows the flash to determine the correct power dosage in relation to the distance of the subject, depending on the overall exposure of the image and the nature of the subject, whether it is light or dark and its reflection.

I advise you to stay in TTL when you use your flash on the camera body, even if the best way to understand how a flash works is still the manual mode.

Manual flash mode

You control the flash output in incremental values.

The objective is to find the correct aperture in relation to the flash/subject distance to obtain the correct exposure.

To do this, simply enter the Flash/Subject distance on the flash in manual mode.

You will get the opening value to use.

When the flash is used off-camera, i.e. out of the camera body, it is the best solution to control the light.

I won’t talk about this strobism technique here, but it will be the subject of a complete and dedicated article.

Flash Exposure Compensation

This function increases or decreases the flash output to properly expose an image to the flash.

It’s up to you to find the balance for your subject.

The background will be exposed thanks to the shutter speed.

The sync modes

Remember that dark background you may have seen one day on your flash shots, well that’s because of the Synchro-X.

Synchro-X speed is the fastest shutter speed that allows the first curtain of the shutter to fully uncover the sensor.

Be aware that when photographing with a flash, the flash duration of the flash must be synchronized with the camera’s shutter opening.

There are several synchronization modes for different uses.

Front Curtain Synchronisation (Front Curtain Sync)

This is the default mode your camera is set to.

The flash fires a short-burst when the first curtain opens and fully unveils the sensor.

In general, the sync speed is limited to 1/250th of a second, but not all the time, depending on the camera.

Keep in mind that if the shutter speed is equal to or slower than the X-sync, the light from the flash will illuminate the entire surface of the sensor.

However, if the shutter speed is faster than the sync speed, only part of the sensor will be illuminated by the flash burst, leaving the curtain on the picture.

That said, this mode is perfectly suited for most shots.

However, when you want to take pictures of a moving subject with a slow shutter speed, choose the second curtain sync mode instead.

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Rear Curtain Sync

Its operation is very simple, since unlike synchronization with the first curtain, the flash flash passage arrives before the second curtain begins to cover your camera’s sensor.

As I just told you above, this mode is particularly interesting for taking pictures with slow shutter speeds on moving subjects in order to give the impression of movement.

High speed synchronization (HSS or FP)

In order to exceed the synchro-x speed, manufacturers have developed a technique that allows high speeds to be used.

Remember that normally the flash in normal mode emits a single flash to illuminate the sensor.

In this mode, the flash emits multiple, rapid, low-powered bursts in succession.

In order to be able to take advantage of the high speed sync, you need a flash with sufficient power, because its maximum power drops enormously with this technique.

You will still be able to use any speed that exceeds the synchro-x speed up to the limit of your camera.

These high speeds serve to freeze the action, even in full sunlight.

Very useful for balancing subjects not far away in backlighting.

By choosing high shutter speeds, you can select larger apertures to restrict the depth of field.

Beware of the diffusers on the flash which would make the power drop a little more.

Finally remember one thing: The lower the flash power, the faster the flash, and vice versa.

The characteristics of the flash and the different ways to use it

When there is little light, the flash can serve as your main additional light source.

Conversely, when the ambient light is abundant, many beginners don’t think about using the flash on their camera.

It’s a shame because it can often save you an image.

This technique, called “Fill-in”, consists of balancing the flash illumination and the ambient light.

It can be used to unblock the hard shadows that the sun can cause or to unblock shadows in backlight.

Feel free to use the exposure correction The built-in flash is a feature found on many cameras.

It can be used in main lighting but you will be very limited by its functions.

It often provides a strong and overwhelming light at close range.

It is too weak to illuminate a distant subject.

It’s not steerable, and that’s a real handicap.

It provides hard shadows without relief.

The built-in flash is too close to the lens axis, causing red-eye to appear.

Vignetting and drop shadows when using wide-angle or macro photography.

The cobra flash is probably the most suitable for use as the main light on the camera.

It will also be very effective for the Fill-in.

It is powerful, and allows the use of smaller apertures, unlike the built-in flash.

It can be rotated, swivelled.

The interest is to create a direct or indirect main light in order to to diffuse his light.

As its light is further from the optical axis, the appearance of red eyes is very limited.
It can be used wirelessly or wirelessly to create more creative lighting.

It can be fitted with accessories for shaping, diffusing, colouring or concentrating the light.

The cobra flash usually has a built-in diffuser and a tongue acting as a reflector.

This article ends here, thank you for following it, I hope you’ve learned things, and even if there are still many things to say about the flash, I’m not done with it yet.

going Further :


Now Your Turn

Now I would like to know, do you have any question ?

Or maybe do you have some information to add ?

Either way, let me know in the comments below

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