However, flash is also handy in several other situations, even when shooting outdoors when the sun is out. It can be harnessed to help you make the most of natural (also known as ambient) light, even on the brightest of sunny days.
Why use flash during the day?
There are three main reasons to use flash when shooting in daylight:
1) You might have noticed that during the middle of the day, shadows become very harsh. If youíve ever tried photographing people at this time, you've probably also noticed that these harsh shadows donít make the most flattering portraits. The sockets under the eyes, nose, chin and hairline may darken, to the point that a very strong contrast is created, and this doesnít look good. Take a look at the photo below, for example.
Image taken by Jean Dow
2) You might also be faced with dappled light, and no ability to control it (at an event or a wedding, for instance, where you have no say over where your subject is standing). Dappled light is the result of light filtering through trees and casting patterns that look odd and are uneven, like in the photo below.
3) Finally, if you are shooting a backlit subject and there is limited light to illuminate them from the front, their face and skin tones may look dark and flat, as the subject does in the photo below.
The aim of using your Speedlight is to fill in these underexposures, and improve the overall appearance of the shadows; all the while making it appear like your subject is lit by natural light, not washed out by flash. This is whatís known as fill-flash.
Why not use a reflector?
Given the skills you have to learn to use a Speedlight, using a reflector can seem like an easier and more affordable option. Obviously, a reflector creates light by reflecting it from the main light source (usually the sun). For this reason the major downside to using a reflector is if the light source starts to fade (for example if the sun sets or goes behind the clouds), then it becomes just about useless. It also requires you to have an assistant or a stand to hold it and position it out of frame, which can be inconvenient.
A Speedlight creates its own light, which can be adjusted to balance the amount of ambient light, even if it changes constantly. It isnít without its own limitations and it takes time to learn how to keep the flash soft enough to look like natural light, but it definitely enables photographers to take photos more easily in challenging light.
How to use fill-flash
Depending on your model of flash, you may have either automatic mode (often known as TTL, P-TTL or E-TTL), and some form of manual mode, or both. Use whichever of these settings youíre most comfortable with.
Aim to fill in the shadows, without compromising your overall exposure. If itís a sunny day, you want to make sure that your background and your subject are still exposed for the ambient light, before adding the fill-flash. Take a look at the image below where the background has been exposed naturally, before the fill-flash has been added to the subject's face.
If youíre working with an automatic flash, you may find that you have trouble getting soft light, as in the following image.
A solution to this might be simply moving the flash further away from the subject. If you have a longer lens you can get further back whilst maintaining a close crop. Alternatively, you can use manual flash mode and drop the power level down by a few stops. Shooting portraits at around 1/16 or 1/32 power is usually adequate to fill in shadows, while still maintaining a natural look.
Experiment at different times of day with various settings to see how each gives a different output of light.