Not just there for life’s darker moments, a flashgun can make a massive difference to the quality of lighting, even under the midday sun. Indeed, they’re particularly useful for softening or eliminating unsightly shadows in sunny-day portraits. However, whether you’re shooting against a backdrop of night-time city lights, stepping indoors for some interior shots, or competing with the beaming sun, successful flash photography is all about creating a balance.
Trying to work out how much flash power you need in any given situation used to demand some mental (and sometimes maddening) arithmetic. Nowadays, thanks to TTL (Through The Lens) flash metering, your camera can team up with a dedicated flashgun to strike a great balance between exposing for ambient light, and applying regular TTL flash metering, this takes more account of ambient lighting levels. Indeed, TTL-BL is the default flash mode for most of Nikon’s recent flashguns, and is available in all models in this group apart from the Gloxy and Phottix, which only give the option for regular TTL metering.
The most direct flash route is to slide your flashgun into your camera’s hotshoe, point and shoot. This can yield decent results, but images tend to have a two-dimensional ‘snapshot’ look. All the flashguns on test have bounce and swivel heads, enabling you to fire the flash at a wall or ceiling instead of directly at the subject. When reflected off a large white surface like a wall, the size of the light source effectively becomes very much bigger. This generates a much softer quality of light that’s much more flattering for portraiture.
Guide number (Gn)
This is a measurement of flash power, usually quoted in metres at ISO100. Dividing the Gn by the aperture value gives the distance the light will reach and still Illuminate the subject sufficiently. At ISO100 a flash with a Gn of 60 will be able to illuminate a subject 15m away at an aperture of f/4 (60÷4=15).
You can also get much better results by using your flashgun off-camera. The traditional way to do this is to use a flash extension cord which links the flashgun to the camera’s hotshoe via a stretchable curly cable. However, most current flashguns have wireless communications built in, so they can operate in master or slave modes for multi-flashgun set-ups.
A down side of bounce flash, especially in areas with very high ceilings or distant walls, is that the light from the flash has to travel a lot further. The intensity of light drops off according to the inverse square law (here comes that maths again), which basically means that if you double the distance you only get a quarter of the light. You can therefore find your flashgun coming up short on available power if you try to bounce the light too far.
For direct flash, at least, all the flashguns on test apart from the Nikon SB-500 have the advantage of an automatic, motorised zoom head. This means they narrow the flash beam to keep in step with longer zoom settings or when changing to a lens with a longer focal length, typically over a range of 24-105mm (FX cameras), or 16-70mm (DX). After all, there’s no point wasting power illuminating a wide area if you’re only shooting a narrow area with a telephoto lens.
10 things we learned
1. On the button
Not just for raising the pop-up flash, the flash button also enables you to select different flash modes, using either the pop-up flash or an external flashgun.
2. Red-eye reduction
This uses a burst of pre-flash light to narrow the pupils of your subject, which will reduce or eliminate the red-eye effect that can spoil flashlit portraits.
3. Slow sync flash
With slow sync flash, flash is used at a slow shutter speed to give a better balance between flashlit subjects and dark backgrounds, or to freeze movement in low light.
4. Rear-curtain sync
Select this option and the flash fires at the end of the exposure instead of the beginning. It’s useful when you want to freeze the action at the end of a long exposure.
5. Auto FP
This is a ‘high speed sync’ flash mode, which enables the flashgun to be used at fast shutter speeds, albeit with a lower maximum flash power being available.
6. Repeating flash
Available in some flashguns as well as the pop-up flash of some upmarket D-SLRs, this programmable mode gives a stroboscopic effect during long exposures.
7. Diffusion dome
Some flashguns come with a diffusion dome, or you can buy one separately. They’re great for softening the light and creating a mix of direct and bounced flash.
8. Command module
The pop-up flash in most upmarket D-SLRs, such as the D7200, can be used as a wireless commander for triggering compatible remote flashguns in slave mode.
9. Spot on
To switch from TTL-BL (Balanced Light) to regular TTL mode (which takes less account of ambient lighting conditions), you often need to switch to the camera’s spot metering mode.
10. Faster recycling
NiMH (nickel-metal hydride) batteries generally enable faster recycling speeds than alkaline batteries, especially after a high-power flash discharge.