Kit: The Flash Gun
An essential to most, the humble flash gun can contain very sophisticated electronics to make the illumination of your subjects just right – but lets see if you need a bells and whistles models for what you shoot, or will an entry level flash gun do what you need.
This article is aimed at beginners who have a dSLR / SLR or bridge camera (see types of camera) and are looking to invest in kit to improve their photography. Here I detail what a flash gun is, what it does, and some of the features common to commercial flash units.
Introducing the Flash gun (and why you will want one (or more))
A flash gun (also called a “hotshoe flash” or “flash unit”, or inaccurately, a “speedlight”) is a powerful electronic flash devices that emits a pulse of high quality close-to-monochromatic light which is far more powerful than the “pop-up” flash on your camera. It connects via the “hotshoe” on top of your camera, and advanced models communicate with the camera, assisting in focus and taking metering data from the camera to produce the correct amount of light for your image. Creative and purposeful lighting of your subject is critical across most areas of photography, and a flash gun is probably the place where people start. The term Speedlight, refers to Nikon’s brand of flash guns, but for many it has become synonymous with “flash gun”, in the same way that Hoover has with vacuum cleaners. Canon and Ricoh both use the phrase “Speedlite”, to buy into the name. The flash unit is powered by its own power supply (usually 4 AA batteries), which means that the camera battery no longer powers lighting solutions, and so will last longer than when using the pop-up flash (significantly so, often up to 50-60% longer).
Guide Numbers and Power
Flash guns vary in power, and they are usually explained as a guide number (GN), rather than Lux or Watts.
Guide number = distance x aperture (f/number)
for a given sensitivity (ISO). The standard is to note the distances in metres and the ISO at 100.
let’s take a look at a flash gun with a guide number of 10 (which is actually really weak)….
GN (10) = distance x f/number
Therefore it will correctly expose a subject at 1 metre distance at an aperture of f/10.
It will also correctly expose a subject at 2 metres distance at an aperture of f/5… and a subject at 5 m at f/2… and so on.
Take a look at my article on the basics to understanding your camera if the terms are unfamiliar to you.
So the higher the GN the more powerful a flash gun is, but its not linear due to the way light falls off: it obeys the inverse square law. This stipulates that as you double the distance from the light source to the subject, you quadruple the amount of light required to correctly illuminate the subject (e.g “distance factor” squared). Thus a flash gun with a GN of 20 is FOUR times more powerful than a flash gun of GN of 10, not double.
Raising the sensitivity (ISO) of the camera will increase the Effective GN of the flash gun, which is pretty intuitive – your camera sensor is more sensitive so it requires less light to properly expose an image.
OK that’s the end of the physics lesson, I promise.
A note on power:
These devices suck a whole lot of juice. I would invest in some good quality high-drain rechargeable batteries – I have 2 flash guns each requiring 4 x AA batteries, my camera bag usually stocks 16 x AAs (e.g. each flash gun has a full spare set). Be aware that flash guns can get really warm as the constant high drain heats up the batteries. Modern flash guns have a temperature detector that cuts off the flash when it gets too warm (I often then swap to my other gun whilst I wait for the hot one to cool down). Each brand of battery is different at how it maintains its current and voltage across its discharge cycle – you’re gonna have to experiment to find ones that work for you. Also, rather than having batteries rolling about in your bag (unsafe, and looks less professional when scrambling in your bag for them), consider getting battery cases (amazon, 99p each) – they’ll hold 4 cells safely for you in a solid casing.
As flash guns connect to the camera via your camera’s hotshoe (we’ll leave remote and cabled flashes until later in this article) – your camera must have a hotshoe in order to use on (sorry NEX fans, and iPhon’ers), SLR/dSLR and bridge cameras all have proper hotshoes, though these vary into 2 camps:
Sony have their own special hotshoe (they took it from Konica Minolta when they acquired their SLR camera section- realistically it just makes buying kit more expensive). Every other camera company have a single traditional hotshoe – which means you can buy Nikon Speedlights for your Canon camera, and vice versa. There are 3rd party flash guns by companies such as Sigma, Metz, Jessops, Ricoh, and Yongnuo and many of these models come in both standard and Sony hotshoe fits. Usually third party flashes are designed to compete with specific models of premium brand flash guns but are cheaper.
Some performance hybrids like the Sony Nex have their own specialist hotshoe which only fits a very specific flash unit for that camera – normal flash guns will not fit it – this is a significant limitation to that style of camera.
Flash guns can be relatively cheap for the entry level models. Third party entry level flashes start at about £70, and intermediate models (premium brand) can range up to £250. The most elite versions at the top end of the market can cost a whole lot more (for example the Canon Speedite 600EX-RT, with a staggering GN of 60 retails around £500).
Not all flash guns are made equal. Some come with all kinds of sophisticated controls and interface options, whilst others are plain and simple portable strobe devices. Here is a small list of features that you will want to check that a flash gun has before buying it, what they features are used for, and whether they are essential to your photography (or not).
Rotate and Swivel (bounce, swivel, zoom)
Full bounce and swivel control is not just a nicety. When I bought my first flash, which was pretty entry level, I quickly learnt the limitations of not having swivel control. Below demonstrates how swivel and bounce allows you to rotate the direction of the flash. Cheaper models tend to have bounce but no swivel, and more expensive models have various bounce and swivel configurations.
When shooting people you basically never want to light them with direct flash, it looks unnatural, unflattering and can cast harsh shadows over the subject’s shoulder (edging). To this end, most togs who have the flash on the camera will seek to use bounce flash (bouncing the flash off of a wall or ceiling in order to disperse the light over a bigger surface, and to change the direction of the shadows on the model). Bounce and swivel modes on a flash gun make this possible even when shooting portrait. Take a look at my guide to basic lighting for more on creative lighting.
Although their primary purpose is just to send out a pulse of nice and relatively even light for you to capture, some advanced flashgun have massively complex displays and controls on the back. Recently when conversing with a fellow tog, they commented that the controlling the Nikon SB910 was like playing “a video game that you simply can’t win” as the controls are pretty intricate:
The bottom end of the flash gun market often don’t have many controls (my first flash didn’t even have an off button!), with limited options for power control. More advance flash guns allow you to set up metering modes, zoom (where the flash head moves forward or back from the flash window on the gun to widen or narrow the emitted beam) and select trigger modes.
Focus & Metering Assist
Most flashguns have a big red sensor on the front that helps your camera to focus faster (it communicates via the hotshoe). This can speed up the focusing in low light, and make it much more accurate – for most of my photography this is a real bonus. Some more advanced models help to meter the light, and adjust the strength of the flash (and informs the camera of its power so your exposure is properly compensated).
Slave / Master capabilities (sync cable / IR / Radio)
A flash gun does not need to live on your camera’s hotshoe. In fact the REAL creative rewards come when the flash is “off-camera”. Most flash guns will allow you to trigger them remotely using the camera’s pop-up flash. Some have native IR sync, and the elite models have radio sync built in. Radio sync is preferred as it does not require line of sight from the transmitter to the flash gun’s trigger sensor. Realistically, most serious togs have radio triggers that attach to the hotshoe connector on the camera, and on the flash, to add radio triggering to any flash gun (e.g. Pocket Wizards). A point of note is that the faithful sync cable port is not found on all flash guns, and appears to be fading away as wireless options become cheaper (the same is not necessarily true of studio strobes). More advanced flash guns can be ” grouped” to trigger together, and even trigger from multiple cameras (shared flash), which is useful if you are working a shoot with a support tog.
High Speed Sync (HSS)
High Speed Sync allows a flash gun to work for images where your shutter speed is faster than the sync speed of a traditional flash. This is usually about 1/200 to 1/250th of a second. It seems a bit weird to think that a shutter can move faster than the flash (e.g. the speed of light) – it can’t, but there is an artifact in the way a camera takes in the light, due to the way the shutter works (see this article for the basics on how the camera works). I’ll not go into the complexities of how the shutter leafs (or “curtains”) move in such a way as to make super fast exposures in this article (though its an interesting mechanical topic that I might put in a more advanced article), but suffice to say that if you shoot above the sync speed you will note a black line across your images (perpendicular to the motion of the shutter), unless the flash gun has been set to HSS mode. HSS mode makes the flash gun fire an elongated beam of light (say 1/10th of a second), which negates this sync problem. It does however eat through batteries (a normal set of cells will last me about 300 flashes , if they are all HSS, the same cells will last me about 60 flashes, give or take). A decent flash gun will move to HSS automatically when it detects that your shutter speed is faster than 1/200th of a second – however some flash guns will only allow HSS in certain directions – e.g. Sony HVL-36AM will only allow HSS when the flash is facing directly forward, but not upwards. The Sony HVL-42AM will not allow HSS when it’s head is swiveled – it tells the camera that you cannot shoot above the sync speed and locks it out in the camera, which is annoying, but prevents you shooting and thinking you nailed the image in error.
Getting Creative with a flashgun (or two… or more)
OK that’s enough about the kit, lets talk very quickly about what we can do with it (or them, many togs buy a couple of flash guns for multiple light sources on the move).
Taking your flash gun off-camera
As I mentioned earlier, taking the flash gun off of the camera and setting up creative lighting can really make a huge difference to your images. Drama, texture and shadowplay become really powerful artistic tools.
Bite the bullet and buy some cheap radio triggers to try out – instead of the professional quality Pocket Wizards that are pretty pricey, you can pick up some cheap and cheerful radio triggers on amazon that’ll cost you less than £20.
Multiple flash units
If you are lucky enough to have more than one flash unit, or friends that will share with you, you can set up the flash guns to trigger on the same signal (if you are using radio or IR triggers you set the same channel). They needn’t be the same model of flash gun, or even the same brand if you have proper triggers. On occasion, colleagues and I have shot the same events and set our flashes up to sync together for certain parts, so we can all get a bit creative.
At the very beginning of this article I said that a flash gun is great way to start out with creative lighting for your photography. In a previous article I spoke about the basics of creative lighting, which included using modifiers like soft boxes, brollies, gels, grids and the like. All of these modifiers are suitable for flash guns, all you need is a light stand and a modifier (or at a push, somewhere to sit the flash and lean your modifier over).
Take a look at the Interfit Strobies Flashgun Bounce set (cost about £35), for some easy fit modifiers for your flash gun, it’ll get you thinking about how to use your flash more creatively.
There is no doubt about it: a flash gun is a critical piece of kit if you are interested in creative lighting in your images (or if you just want to shoot in low light conditions (typically we consider ” indoors” as low light, even with the lights on).
A decent flash gun is more than just a source of light, and it opens up virtually endless creative possibilities. Investing in at least an intermediate model is worthwhile, as you may outgrow cheaper versions (e.g. those without full swivel, and staggered power control), grab yourself some batteries and maybe a radio trigger array and then you’re all set to start getting creative with deliberate lighting. If you use it properly and to its fullest, this will certainly change your game.