Problem No. 71: Why do my flash shots keep coming out dark?
The most likely explanation is that you're trying to shoot subjects that are too far away. Flash has a limited range, and built-in units are weaker than external flashguns.
Problem No. 72: When I use a flashgun with my DSLR, foreground areas usually look nice and bright, while the background detail is thrown into darkness. How can I fix this?
Flashguns offer effective illumination for foreground objects, but when these are correctly exposed, background areas can look dark. the trick is to balance the flash output with ambient light. Many DSLRs offer a slow-sync flash mode, which combines flash with a slow shutter speed to give a balanced exposure.
With Canon cameras, you can do the same by switching to Av (Aperture value) shooting mode when using flash. To fine-tune the balance, apply exposure compensation in the camera to brighten or darken the background area, then apply flash exposure compensation to adjust the foreground brightness.
Slow-sync flash can result in slow shutter speeds, so camera shake can become a problem. Increase your ISO, typically to between ISO 400 and ISO 1600, to enable faster shutter speeds.
Problem No. 73: My flash exposures seem to vary. Portraits against white come out dark, and off-centre subjects are too bright. What's wrong?
The TTL flash metering system should give good results in most conditions but it's easily fooled. Very light areas often result in underexposure, and you may need to add around +1EV of flash exposure compensation for white whites.
With off-centre portraits, the metering system aims to correctly expose what's at the centre of the frame. If this corresponds with an area of background that's significantly further away, then the subject can be extremely over-exposed.
Zoom in to fill as much of the frame as possible with the person's face, then activate the Flash Value Lock. Now zoom out again, recompose the frame and take your shot.
Problem No. 74: I've tried freezing motion with flash, but get ghosting around moving people. Can I fix this?
The pulse of light from a flashgun is short, at 1/1000 sec or faster, so can help to freeze action and avoid camera shake. But most cameras default to a slow shutter speed of 1/60 sec when using flash.
You can still freeze action if the ambient light is dark, since the flashgun will be the only effective light source. But brighter ambient lighting will affect the exposure, so you'll probably get a ghost image of anything that doesn't stay still.
The best solution for this is to increase your shutter speed to the maximum sync speed available in your camera, which is often 1/200 to 1/250 sec (check the camera manual). But here you run the risk of making backgrounds look dark compared with flash-lit foreground areas.
For a more balanced, natural-looking exposure, free of ghosts, increase the camera's sensitivity to around ISO 800-1600.
Problem No. 75: I use my Canon DSLR in Av mode practically all the time, as I like to have full control over the aperture setting. The only problem is that some of my shots are quite blurry when I'm using flash. Why is this?
When you use a Canon DSLR in Aperture Priority (Av) mode, either with the pop-up flash or with a separate flashgun, it tries to balance flash with available light as much as possible. This makes for more natural-looking photos, especially with fill-flash in sunny portraits.
But under very dull lighting, you can end up with slow shutter speeds - the resulting effect often being referred to as 'slow-sync' flash. You can use slow-sync flash to your advantage, freezing the foreground with a very short pulse of light, while enabling plenty of motion blur in relatively distant background objects.
However, you can also end up with unwanted blurring of the background due to camera-shake, while even close or midrange objects that are moving can also take on a ghostly blurred appearance. To tailor the flash effect, you can adjust Av flash mode in Custom Functions.
The Canon 550D, for instance, has three options: the default Auto setting; to limit shutter speed to between 1/200 sec and 1/60 sec; or to fix the shutter speed at a fast 1/200 sec. The last of these is good for freezing action, but can make backgrounds very dark.
Problem No. 76: What's the best way to avoid red-eye in portrait photos?
Red-eye is caused by the flash reflecting off a subject's retina. With digital SLRs, you're most likely to notice this with distant subjects shot in dark settings. Your DSLR has a red-eye reduction flash setting, which in the majority of cases uses the AF-assist illuminator lamp.
Shining this for a second causes the subject's pupils to contract, reducing the appearance of red-eye. However, the delay involved is hopeless with moving subjects, and kills any spontaneity. Plus, on-camera flash can look ugly.
One option is to use a separate flashgun, so the flash can be angled or bounced to change its direction. But don't forget that any recent DSLR will perform well at ISO ratings of 1600 or 3200, if not higher. With the aperture wide open, you can shoot in most lighting conditions without flash.
Or failing all that, find out how to remove red eye in Photoshop in 4 easy steps.
Problem No. 77: When using a flashgun for indoor portraits, I usually end up with a dark shadow on the wall to one side of the person's head. Is there any way of avoiding this?
Try and keep some distance between your portrait subject and the wall behind them, then bounce the flash off the ceiling to reduce the harshness of shadows. Better still, use a diffusion dome and an off-camera flash cord, so you can hold the flashgun higher up and slightly to one side.
Problem No. 78: The lighting from my flashgun seems very harsh for portraits and doesn't do my subjects justice. How can I get a softer lighting effect?
The softness of light depends on the relative size of its source. On a bright, sunny day, the physical size of the sun is enormous, but it's so far away that you can cover it with the palm of an outstretched hand.
On a dull, overcast day, the whole dome of the sky becomes a vast light source, giving a much softer light - ideal for portraiture. A flashgun head is small, so it will produce a hard lighting effect.In portraits, this will accentuate every flaw and blemish, and produce dark, unsightly shadows.
An effective way of softening the quality of light from a flashgun is to bounce the flash off a white wall or ceiling, as this makes the light source much bigger. Better still, you can fit a flash diffuser such as the Sto-Fen Omni-Bounce to your flashgun, then angle the flash head to about 45 degrees.
The diffuser will throw some of the light forward as well as bounce it off walls and ceilings. When there are no bright walls or ceilings available, a more sophisticated flash diffuser is required.
It's also a good idea to use a slower shutter speed, or to increase your camera's ISO, to balance ambient light with the output of the flash, and avoid overly dark backgrounds.
Problem No. 79: How can I get better looking portraits on sunny days? In most of my shots, people's eyes are dark and there are deep shadows on their faces - but I've heard that flash can help here.
Sunshine is the enemy of portraiture, as it creates a hard and unflattering light. When the sun is low in the sky, people will squint, and when it's overhead, there will be deep shadows that turn their eyes into black holes.
The answer is to get your subject to turn away from the sun, so they can pose naturally, and to use fill-flash to banish shadows. When using a flashgun with TTL (Through The Lens) metering, most cameras will do a decent job of balancing flash light with ambient light, giving fairly natural results.
Canon DSLRs do this best in Av (Aperture value) mode, while Nikon's BL (Balanced Light) flash mode is similarly good. To tailor the results, switch to Manual and select an aperture and shutter speed that gives the correct exposure for the overall scene.
Use the camera's metering system as a guide, but don't exceed the maximum shutter speed for flash synchronisation - the flash sync - typically around 1/200 sec. The TTL flash exposure system should enable the right amount of illumination for fill-flash, but be prepared to dial-in some positive or negative flash exposure compensation. Again, for ultimate control, switch to manual power settings on the flashgun and adjust the power for the best balance.
Another good option for natural-looking fill flash is to use the flashgun off-camera, holding it high and to one side of the subject, using an extension cord or wireless connection.
Problem No. 80: Why does the pop-up flash on my Canon camera flicker?
Many Canon DSLRs, including the more advanced 60D and 7D, have no AF illuminator to help them autofocus under very dull lighting. Instead, the pop-up flash emits a brief series of pulses of light to illuminate the target.
You can switch this off in the Custom Functions menu, or ensure that only the less annoying infrared AF beam is triggered when using a compatible external flashgun.
Problem No. 81: Should I set the flash to first curtain or second curtain sync?
Most flash settings work in a 'front curtain' or first curtain mode - and it's this mode you should stick with for the majority of situations. The term itself is a hangover from bygone times but basically means that the flash fires just after the shutter opens, making it excellent for situations that require precise timing.
Rear curtain or second curtain flash mods is a more rarely used setting, where the flash fires at the end of the exposure, just before the shutter closes again. Imagine photographing a car with its lights on, coming towards you at night, using a long shutter speed of around three seconds.
Rear curtain flash would illuminate the car when it was closest to you, with light trails appearing to stretch out behind it. Front curtain flash would have illuminated the car at the start of the exposure, when it was furthest away - the light trails would then appear to stretch out in front of it, providing a less 'natural' result.
Problem No. 82: I've got an old flashgun from decades ago, which I used to use on my film SLRs. Is it possible to use the flashgun on my DSLR, albeit without dedicated functions such as TTL metering?
There's a big risk involved with using old flashguns on new cameras. Even if they physically fit the hotshoe, and the trigger connection is in the right place, some old flashguns use voltages that run into hundreds of volts. This is more than enough to zap the circuitry in most DSLRs, which are designed for a voltage of just 5V to 12V
PAGE 1: General Photography Problems
PAGE 2: Using lenses
PAGE 3: Digital camera accessories
PAGE 4: Digital camera settings and controls
PAGE 5: Camera exposure
PAGE 6: Using flash
PAGE 7: Photography technique
Flash photography tips: external flash techniques anyone can understand
Flash photography made easy: master everything from pop-up flash to multiple flashguns
Flash photography basics: every common question answered
How camera flash works: free photography cheat sheet