Flash photography: Guide to buying a speedlight and shooting with an on-camera flash

A flash, or sometimes called a strobe or a speedlight, consists of 3 parts: head, body and foot. The foot contains electrical contact points that are used to trigger the flash into firing, while mounted on the camera’s hotshoe, when the shutter release button is pressed.

Popular camera manufacturers, such as Canon and Nikon, have their own line of flash units that can be used with any of their available camera models. Some flash units’ functionality like the Nikon flash needs to be set from within your camera’s menu, while some others like the Canon flash units are set from the flash itself.

Most decent digital cameras have a hotshoe mount on top that takes an external flashgun. On the hotshoe, you’ll see a number of small contact points along with one larger contact point. The large point fires any kind of flashgun mounted on the camera, while the small points are there to connect dedicated matching flashguns for easier and simpler flash photography.

If you own a Canon camera, it’s best to get yourself a canon speedlight for maximum compatibility and available functionality. Same applies to other camera brands in case they have their own flash line.

Flash Power

Flashguns are just another source of light that we can use to illuminate a scene, much like sunlight or window light. The only difference is, we can control its intensity and direction. It’s nothing to be afraid of, it’s something we can use to our advantage.

Just like aperture and shutter stops, flash guns have stops as well indicating the amount of light they can emit. These are referred to as flash power, and are measured in half increments. As follows:

1 » 1/2 » 1/4 » 1/8 » 1/16 » 1/32 » 1/64 » …etc

Practically named: Full power / half-power / quarter-power / …etc respectively.

A change of manual flash power level to half (i.e from full power to half-power, or from half-power to quarter-power) is a one stop difference.

So when you’re out buying a new flash unit, one thing of concern is its power. Meaning, how much light it emits at full power. This is indicated by something called, the guide number.

Flash Guide Number

A flash guide number evaluates its power and ability to illuminate a scene at a certain film speed or sensor sensitivity. A higher flash guide number means a more powerful flash.

“The guide number is the product of the maximum flash-to-subject distance and the f-number of the aperture, that will correctly expose film or a digital sensor with the specified sensitivity.” ~ Wikipedia

The formula goes as follows:

GN = distance × f-number

Where GN is the flash guide number, and is the product of the distance between the photographed subject and the flash multiplied by the aperture (or lens opening).

Guide numbers could be given in feet or meters depending on the flash manufacturer, and are usually based on an ISO 100 film speed or sensor sensitivity. Whatever the case may be, the previous formula still applies regardless.

“The guide number represents an exposure constant for a flash unit. For example, a guide number of 80 feet at ISO 100 means that a target 20 feet away will be correctly illuminated with an aperture of f/4 (80 = 20 × 4) using a sensitivity of ISO 100. For the same guide number and an aperture of f/8, the light source should be 10 feet from the subject (80 = 10 × 8).” ~ Wikipedia

Bottom line is, when you’re out shopping for a new flashgun, the higher the guide number at a certain sensor sensitivity, the more powerful the flash is, and the better.

Flash Metering Types

Three main flash metering types are: TTL, ETTL, and ETTL 2. TTL stands for “through the lens”. When the flash fires during the exposure, not all of its emitted light makes it back to the sensor to record an exposure. Some light is actually lost. So for the camera to know how much returned light it needs for a exposure, it needs to measure it. This is were flash metering systems come into play.

TTL flash metering is the oldest and the most basic of all three. It works by emitting light to illuminate a scene. This light keeps coming back to the camera until the camera sensor gives it a signal that it has received enough light for a proper exposure, consequently turning the flash light off.

ETTL stands for “evaluative through the lens metering”. It works by emitting light prior to the actual flash light that is used for registering the exposure. This first light is known as the pre-flash. It then measures the amount of light returned through the lens and compares it with the original amount of light emitted, taking into account the distances between the camera and the photographed subject (indicated by the focus point in the frame). Based on those facts, it then calculates how much light a flash fire needs to emit in order to register an appropriate exposure. And so it fires the main flash light once the scene is exposed.

ETTL 2 basically works the same as ETTL flash metering system, only with a few additional useful features for a more accurate exposure. It has improved calculation methods, it can determine reflective surfaces within the frame and incorporate this info into its calculations, and more.

So as you see, if you’re not planning on shooting with your flashgun in manual mode the whole time, ETTL 2 flash units are your best bet.

Shooting with one on-camera flash gun

Now, you’ve got the right flashgun for your camera, and you need to start making some flash photography right? Well, all you need to do is take out your flashgun, mount it on your camera’s hotshoe, secure it by turning the ring on the flash foot to secure it in place. Next, turn on your flash, select the ETTL 2 metering mode (note that even if your flash is an ETTL 2 type, the display on the back of the flash unit will still read ETTL only but its actually ETTL 2), and you’re good to go.

Shooting with an on-camera flash gun differs a bit when using a Canon camera than when using a Nikon camera. Like let’s say, you have placed your model against a nice background outdoors. When you take a shot, your background is basically exposed by your camera, while your model is exposed by the flash light. Let’s assume you want to darken the background a bit while leaving your model’s exposure intact. You set your camera to AV mode (aperture priority mode), you ride the exposure compensation down by one or two stops (depending on how much you want to under-expose your background), and you take a shot. Your model is correctly exposed since they’re illuminated by the flash light, and you get a darker (less-interfering) background.

On a Nikon, things are a little different. If you try to take your exposure compensation down to under-expose the background, the flash power is taken down consequently because the change is general. You will be affecting your camera and your flash settings, hence your model will become under-exposed as well. So what you need to do is switch to manual shooting mode (on your camera). Once you set your Nikon camera to manual mode, you will have the camera and the flash working separately. So all you need to do is take your reading off the background (your model will be illuminated by the flash), and then just ride your shutter speed faster than the appropriate indicated setting to darken your background.

For indoor photography, you can just mount your flashgun onto your camera, turn it on, and take a shot. What you will notice however is, the light would be direct and harsh hitting your model much like a built-in pop-up flash would (except maybe from a little higher position with a little more power). What you can do here is make use of walls and ceilings and get all creative. To be able to do this though, you’ll need to have a flash with a tilt/swivel head. What these do is, actually allow you to turn the flash head up / down / to the sides / and even all the way backwards. Once you have one of those you can just experiment and see what fits your situation best.

For example, you can tilt the flash head up so that when you fire a shot, the light from the flash illuminates the ceiling, bounces off of it, hitting your model with a natural more diffused manner. Also if you have a wall beside you, you can turn your flash head either to the left or to the right to face that wall. Now when you fire a shot, the flash light hits the wall and then bounces off illuminating your model from the side for an interesting effect.

When you bounce light from the side, make sure you do that off a neutral surface though. What I mean by that is, if you have a colored wall, once the light bounces back to your model its color is going to be affected by the color of the wall. So if you don’t have any white walls, what you can do is place a reflector and bounce your flash light off of that.

Another cool thing you can do with a tilt/swivel head flash is, turn the flash head all the way to the back. Once you’ve done that, stand with your back against a white wall or a bounce card and take a shot. This way the light from the flash is going to hit the reflecting surface behind you, and then bounce back all soft and diffused naturally illuminating your model from the front.

A neat little trick most flashguns have is, when you’re shooting within a short distance from your subject and your tilting your flash head up and down there’s a tiny little click that you can hear once you push the head all the way down, while pushing on the sides of the flash head with your other two fingers. This tells the flash you’re shooting within a close distance from your subject, so it automatically decreases the flash output so not to overwhelm your subject. Please be sure not to crack the thing though!

I have been getting a few requests asking for posts that talk about flash photography, how to buy the right flash for your camera, and how to go about using it so I decided to post this article for you guys to learn more about the subject. If you do like this, I can take this a little further and teach you how to use your flash light in full manual mode for maximum control and room for creativity. So please do let me know what you think =) Hope you learnt something new today!