How-To Geek

Photography With How-To Geek: When Should I Use a Flash?


Flashes are so convenient that flash photography is practically the norm. But have you stopped to think about what that flash is doing, or whether you need to use it at all?

Built in and mount flashes can allow you to take pictures in low light environments you might not be able to use otherwise, and can change your shot, both for better or worse. Take a look through several different types of photography, and join the discussion with your own experience on when a flash is helpful, and when it can ruin a shot.


Reacting to Light Vs. Controlling It


Photography is all about light and how you choose to react to it, capture it, and control it. Before you take your photos, you’ll want to have some idea what sort of photograph you want to create. In the photograph above (by the author) the settings were manually changed to react and capture as much of the colors, subtle tones, and changes in light as possible in a dark environment. Because shooting with a flash changes the color temperature, light sources, highlights, and shadows, creating an portrait like this one would be impossible with a flash.



However, flashes (and other methods of controlling lighting) certainly have a place in photography. Portraiture, such as these shots by child portrait photographer Amy Douglas, control light two separate ways. The left image uses a lower light environment lit with a studio light to create strong shadows, while controlling highlights and skin tones to create a soft image with dramatic contrast. It’s a good example of a photographer controlling the light in order to create a strong image.

The image on the right is a good, subtle example of a flash. After a conversation with Amy, she discussed her love of using flashes to create smooth, even skin tones—a very different approach to your author’s attempt to capture the dramatic lights and shadows in the photograph above. When comparing the author’s photo and Amy’s, the cameras and lenses used were fairly similar, yet the result could not be more different.


What To Expect: Comparing Shots With and Without a Flash


The left side image does not use a flash, while the right image does. They have both been edited slightly in an attempt to show some of the less obvious differences in flashing and not flashing. The flashed image, for example, feels more polarized, with darker tones and some loss of detail, while the left image is more even, and is reacting entirely to the situational lighting. A flash will react and give strong, shiny highlights on some materials, like glass, or the plastic material shown above. If you find yourself taking pictures through windows, you’ll likely find that most of your flash gets reflected, ruining your shot.



Sometimes using a flash is simply a stylistic choice. Both of these images have been edited—the left does not use a flash, and the right one does. Notice how the shadows move around, as using a flash changes the light by adding an overpowering light source. The heavy shadows cast underneath the hand and cord are softened and moved in the flash shot, and the skin tones have also changed. For the better? It’s hard to say in this situation (Author’s note: although IMHO the flash shot is superior), but the built in flash gives the photographer more options to control light. Even if you’re more of a point-and-shoot, automatic setting only style photographer, it’s never a bad idea to bracket your shots by shooting the same subject with and without the flash.


Proper Flash Use, and The “Fill-In Flash” Technique


Many of us use a flash in those low light environments or night shots—we want to capture pics of our friends in a bar, or the inside of a dimly lit room. In these situations, controlling light is impossible, and slow shutter speeds can make all of your pics blurry. Sometimes there’s no avoiding it—you more or less have to use a flash, and you’re going to get the “flash photography” look. Here’s some things to watch out for when shooting with a flash.

  • Flashes create strong highlights and can white out large areas of your photo.
  • Expect color/temperature shift when photographing with flashes. Flashes use close to neutral white light, and have their own white balance settings.
  • Flashes can flatten values, even out skin tones, and change shadows. This can be either good or bad!
  • Expect very strong highlights on reflective materials like glass.
  • The effective range of a flash is only a few feet, and can create dark backgrounds. (The above image is a good example of this.)
  • Red eye, red eye, red eye! Flashes also can create unnatural white highlights in eyes, as well.
  • Flashes can also create shadows where you don’t expect.
  • Artful use of flashes and/or lamps can create photos with even skin tones that emphasize the subject, rather than light.


Regardless of the shortcomings of flashes, they remain a very important tool in the portrait photographer’s toolkit. The Fill-In Flash technique can be a great way to improve outdoor portraits like the image above. Here’s (roughly) how to get the job done.

  • Shoot a portrait outdoors with settings to properly expose the background.
  • Manually open the flash (usually with a button marked with a lightning bolt), keeping the same settings. Depending on your camera, automatic settings may change the exposure to react to the flash.
  • Shoot the portrait, using the flash to cast light onto your foreground subject.
  • With some experimenting, you should be able to get a good exposure of both your foreground and background.


After all that, when should you actually use a flash? Again, it all comes down to the kind of photo you want to take. If the horrors of flash photography don’t scare you, or your subject is more important than the artsy-fartsy merit of your photograph, you should have no qualms with  blinding your friends with your camera flash. Keep in mind that it is more appropriate in some situations than others, and that sometimes it can create a great image, and other times it can ruin a very good one.

What are your thoughts on flash photography? Share them with us in the comments, or send them to

Image Credits: Flash Flash by Deana, available under Creative Commons. Brad, Copyright by the author Eric Z Goodnight. Photos of Owen, copyright Amy Douglas photography. 40+281 Flash by BarkBud, available under Creative Commons. Fill Flash Experiment by Mike Baird, available under Creative Commons. Other images by the author, hereby released under Creative Commons.

Eric Z Goodnight is an Illustrator and Stetson-wearing wild man. During the day, he manages IT and product development for screenprinted apparel manufacturing; by night he creates geek art posters, writes JavaScript, and records weekly podcasts about comics.

  • Published 08/23/11

Comments (6)

  1. AzwadAhmed

    Awesome article mate!
    for me i just follow one principle, if the flash overpowers the natural lighting, then don’t use it. i rarely use flash indoors, i got a prime lens to deal with the lack of lighting. as for outdoors, i only use flash to remove shadows as long as the sunlight present is pretty bright. thought i’d share this.

  2. Lady Fitzgerald

    I frequently use flash outdoors to fill in shadows (it’s called fill flash). The external flash I bought for my high end point and shoot was the best investment I ever made. The built in flash is dimmer, takes longer to recharge between flashes, drains the camera’s batteries faster, and has less control than the external flash. Since the external flash uses it’s own batteries (four AAs, same as the camera), it’s brighter, charges faster, and doesn’t run the batteries down as fast. The external flash weighs almost as much as the camera but, every time I’ve opted not to lug it with me, I’ve regretted it.

    As the article suggests, I take shots both with and without the flash. Indoors, bouncing the flash off the ceiling or a wall often gives a more even flash without the glare. My flash has a built in diffuser that spreads the flash for wide angle shots but also serves to soften the flash a bit. I also have a diffuser that fits over the flash that is especially useful for bounce flash. There is a way to control the intensity of the flash with the camera settings but I haven’t gotten around to learning how to do so without a lot of fumbling around (yet).

    One tip for people using a built in camera flash and finding it’s too intense is to place a layer or two of tissue paper in front of the flash to diffuse the light. Backing off from a shot and using the zoom to bring the shot back in close is another way to effectively diffuse a flash. This works best if the camera has image stabilization (my old shaky hands and I love the guy who invented that!) or is on a tripod (or both).

    One way to avoid glare from glass when shooting through it is to shoot at angle to the glass. Another way is to put the lens as close to the glass as possible (it may be necessary to remove the glare guard to get close enough). Using your hand or a few fingers against the glass between the flash and the lens may help to keep glare from the lens. Since no two situations are alike, don’t be afraid to experiment. One of the beauties of digital photography is one can experiment without it costing a fortune.

  3. Tim

    I think the way to look at it is to consider contrast and lighting ratios for various flash settings.

    1) fill-flash is where the flash contributes continuous, then it’s *key* flash (ie that’s the primary source).

    2) If you use so little flash it barely registers (e.g. f/22 on a distant subject) then you can still benefit from catchlights in eyes.

    3) If you use so much flash it exceeds daylight by a few stops, you can make day look like night-time.

    4) Be *delicate* with fill-flash. Sorry, but the chap in his hat looks *way* better without so much flash at all – the hat-rim and particular his ear cast shadows that conflict with daylight, betraying the use of two light-sources from different directions (as is the case), when the eye *expects* the face to be dark given the prevailing daylight colours. Fill-flash should flicker subtly into the shadows, lifting them out of the range of the noisy end of the sensor response curve. I hesitate to stipulate absolute values, but in portraiture and in my experience of closeup nature shots, starting by having the flash contribute around -1.6 to -1.3EV of the continuous source gives favourable results.

  4. Shadist

    I rarely ever use the flash on my Pentax.

    Every once and a while I will use it to bring out colors when pants/flowers I am shooting end up in shadow due to excessive sunlight. But even then I usually take one or two shots without the flash first.

    The two bonuses I have found are I don’t really think the lack of a flash affects my photography. And the other is that I have had the same batteries in my camera for nearly a year and they don’t show as being even half used yet.

    I usually honestly have no idea what people are doing when they wander around using flash on everything, I find it usually does more harm than good.

  5. PoohBah

    The daylight portrait might have benefited from using a sheet of white paper (A4 or Letter size should be adequate) as a reflector instead of fill-in flash; this would have lightened the shadows noticably without the slight tendency of the flash to over-cook it.

  6. Paul D.

    I find it really funny how many people in arenas and stadiums use flash when taking pictures of the action. It doesn’t matter if it is outdoors in bright sunlight or indoors under a roof, aside from the brightness from the sun, or the indoor lighting, just the distance from the cameras to their subjects means the flash is totally wasted, and only works to annoy people facing the flash. I can only imagine that if they get a good picture because of the sun or the bright lighting in place, they think their flash is what lit the scene!

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