I am sharing with you a great article from Ben Davis in Digital Photo February 2016.
Take more control of the lighting in your images with an accessory flashgun.
Taking control of light is one of the key steps to becoming a better photographer. Whether you’re facing a low-light situation, a strong backlight contrast or you want to freeze some action, there’s lots of circumstances that call for a burst of light from a ﬂashgun. If you’re already using your camera’s pop-up ﬂash unit – but ﬁnd its limitations frustrating – then it’s time to consider investing in an accessory ﬂashgun. And with prices starting at around £90 for a third party model, this modest sum will make a massive diference to the quality of the light in your images, as well as ofering fantastic creative control.
Why should I get a ﬂashgun?
The beneﬁts of a dedicated ﬂashgun over a built-in ﬂash unit are numerous and noteworthy. One of the key advantages is a huge increase in power. An external ﬂash unit is likely to have a Guide Number (GN) of at least 30 – and often it’s signiﬁcantly higher – whereas the weaker pop-up sibling hasa GN of around 12. This means that at the same aperture and ISO settings, the external ﬂash unit is three to four times more powerful than the pop-up. So with an accessory ﬂash you can light subjects at least 7m away, but your range is limited to 3m witha pop-up.
Not only is an external ﬂash unit more powerful with a greater range, but it afords much more control, too. Most dedicated ﬂashguns havea swivel head, so the light can be directed at any angle you choose. This is great for ‘bouncing’ the light, which is the best way to create more ﬂattering results when working indoors.
It’s also faster than any built-in ofering. This is because it doesn’t rely on the camera’s battery, and instead draws its power from its own batteries– usuallya set of four AAs. This makes the recycle times much faster so you don’t miss out on the action, and also you don’t place extra strain on your camera’s battery, keeping you shooting for longer.
How does it work?
All ﬂashguns mount on your camera’s hotshoe, and lock securely in place with a switch or a screw dial. Your camera will communicate with your ﬂash via electronic contacts in the feet. You need to make sure the ﬂashgun you’re using is compatible with your brand of DSLR or CSC. If it’s from the same manufacturer, then there’s nothing to worry about. Third-party ﬂashguns are usually more afordable, however, and often ofer similar features to the own-brand models. Companies like Sigma, Metz or Nissin are a good place to start if you’re after a more budget option – you just need to make sure the one you get is designed to work with your own camera. Most ofer versions for the diferent camera brands.
How to use the built-in bounce card and diffusion panel
Most mid-range accessory ﬂashguns come with a built-in bounce card and difusion panel. They’re discreetly slotted in the head of the ﬂash, and can be pulled out into position to modify the spread of the light to give you more control in your images.
The bounce card is arguably the most useful and versatile of these two features. It’s essentially nothing more than a white sheet – half the size of a playing card – and so if your ﬂashgun doesn’t have one you can easily attach your own with an elastic band. It’s designed to make the light source larger, as this results in a wider spread with softer light and fewer shadows. The bounce card is useful in a range of situations. If you haven’t got a surface to bounce your light from, but don’t want to light your subject with direct ﬂash, then having the head at a 45º angle with the bounce card in place will create a larger light source for more ﬂattering light. The bounce card can also be used in conjunction with bouncing the light from a reﬂective surface like a ceiling. Some of the light will bounce from the surface to create a very wide spread.
This cuts back almost all the shadows, but the bounce card directs some light forwards towards your subject, and creates attractive catchlights in their eyes.
The difusion panel is a translucent plastic panel, with rows of tiny angular cones raised from the surface. These are designed to help difract and spread the light even further, giving you a wider coverage of illumination. It’s most useful for when you’re shooting with a really wide angle lens, and will help to ensure that the light from the ﬂash is spread across the entire frame.
Understanding the flash sync speed of your camera
There is a limit to the maximum shutter speed you can set when using the ﬂash, and this is known as the ﬂash sync speed. On most DSLRs and CSCs it’s set to 1/200sec, though some allow it to be set fractionally higher. If you’re shooting in Shutter, Aperture or Program mode, then the camera will not set a shutter speed faster than the sync speed when the ﬂash is enabled. However, if you’re shooting in Manual mode then it’s perfectly possible to set the shutter speed beyond the sync speed setting. If you do this, you’ll notice a black strip across the top or bottom of your frame when you review the image. This is because the curtain which opens to let light reach your sensor is still travelling when the ﬂash is ﬁred, causing a blackout. If the shutter speed is really fast – like 1/4000sec – then the entire frame will be black. This is because the curtain has opened and closed before the ﬂash has had a chance to ﬁre. The sync speed settings can be adjusted in the camera menu.