Fill-in flash for portraits

The benefits of using flash outside in daylight to brighten up portraits are numerous. For example, it can add an attractive catchlight to a subject’s eyes, help to smooth skin by lighting it evenly and, most importantly, reduce shadows on the subject’s face. However, this can be taken a step further. Rather than merely using a flash to complement light from the sun, you can use a flash to actually beat the sunlight, making the flash the dominant light in the scene.

To do this, you need a camera with a fairly fast flash-sync speed. Thankfully, most digital SLRs can sync at a speed of 1/250sec, and some are even faster than this. The aim is to underexpose the scene, causing the subject to be in almost complete shadow, but then to use a flash to illuminate the subject to create studio-style lighting outside.

Setting the scene

The location in which you choose to take your images is important. While you can use the technique anywhere, finding a shady location with a bright background works well. This allows for your subject to be in shadow, meaning that little ambient light will fall on them during the exposure. As the technique has the effect of darkening backgrounds, it can work well on overcast days to make dramatic, cloudy skies. Equally, on a bright sunny day, it can make the sky a very deep blue. Overall, it creates an effect very reminiscent of HDR, as parts of the image normally in shadow are made bright and punchy.


Having found an appropriate location, place your subject in the scene and ask them to pose. While you can use a flashgun placed on a camera’s hotshoe, results are better when the flash is mounted offcamera. A wireless flashgun is perfect for this, but equally a long sync lead allows you to use a conventional flashgun with the same results.

Using a slave cell may be a good idea if you are shooting a shadow area, but generally they don’t work well, if at all, in bright conditions. Choose an appropriate angle to light your subject. Generally, you want this to be around 45° to their left or right. The precise position depends largely on where the ambient light is coming from. Most flashguns come with a small stand that allows the flashgun to be mounted on to a tripod or lighting stand.

Fill-in flash for portraits

With the aperture set to around f/16 and the sensitivity to ISO 100, altering the shutter speed mainly affects the brightness of the background.

Alternatively, ask someone to simply hold the flash in the required position. In manual exposure mode, set the camera’s ISO sensitivity to ISO 100 and the shutter to the fastest possible flash-sync speed, which in most cases is around 1/250sec. Take an exposure reading without firing the flash and adjust the aperture size so that it creates a nice dark sky. In bright light, f/16 is a good starting point. Having taken your test image of the background, set your flash to full power and take another shot. You should find that the flash lights the subject. If the light is too bright, you can turn the power of the flash down or move it away from the subject until you are happy with the result.

Top tips

Shooting a subject placed in shade allows ambient light to affect the image less, making the fl ash more prominent.

Make sure that the background is exposed a little darker than you would normally.

Set the shutter speed to the fastest possible speed at which the flash will synchronise.

Just as you would in a studio, use light modifiers, such as diffusers and grids, where appropriate.

To help soften shadows, or simply to provide extra light for a full-length portrait, try using multiple flashguns.

Use the sun to your advantage by using it as a backlight.

Try increasing the saturation of the image in editing software for a punchy, vibrant effect.