How to Use Fill Flash for Proper Exposure (step by step guide)
Learn the technique to use fill flash
What is Fill Flash?
Fill flash is a technique in flash photography to get an even exposure in photographs in high dynamic range and difficult lighting situations. One of the ways to get even exposure in photographs, as in getting the correct exposure on the subject with a strong backlight, is to use reflectors. In fill flash photography, you can use your camera’s in-built flash or an external flash to fill the underexposed, or shadow, regions of a photograph.
Do you have trouble using fill flash?
First, let me give you a brief idea about fill flash and why is it used. It is often noticed, particularly when you photograph backlit subjects, that the foreground turns dark while the background is properly exposed. And when you expose for the subject then the background will be over-exposed. This happens in a lot of other situations like when a harsh side light creating a strong shadow.
You may not notice this with your eye since the human eye can cover a high dynamic range than a camera does. So, you have to use different techniques to even out the exposure. One of the techniques is using fill flash. As the name implies, it is filling the dark/shadow areas using a flash. In this post, I am going to explain how to use fill flash with an external flash.
How to use fill flash — 7 questions for best results
- What type of flash do I have?
You may have a pop-up flash or an external Speedlite or flash gun. The type of flash has some significance when you use it as a fill flash. I will walk you through it.
- In which direction the subject is placed?
All flashes may not work best as fill flashes. It depends on the direction of your subject. Almost every camera has pop-up flashes and it can be used as fill flash too. Most point and shoot camera fire the fill flash in automatic mode. One downside of using pop-up flash is that its direction cannot be changed – it is fixed in the camera. So if your subject is situated at an angle and when you photograph them, the flash cannot properly fill up the shadows. But this is not an issue when you are using an external flash as you can keep the flash depending upon the position of your subject
- Is the subject backlit?
If your subject is backlit – more light in the background – you can use the fill flash. A common situation of this sort is when your friend poses for you while the sun is behind.
- Is the dynamic range of the scene is high enough for the camera to record?
Fill flash can be used for other situations when the scene has a high dynamic range which your camera cannot record. One common example is when your friend is wearing a hat under harsh light creating a shadow on his/her face. Another example is strong side lighting.
- How far is my subject from the flash?
This is a really important factor to consider before using fill flash. If your flash, with its maximum output power, is far away from the subject; the fill flash won’t work. The pop-up flashes can light up the subject upto 10 feet. But external flashguns can fire farther distances.
- How to use the flash’s power?
Your distance from the subject and flash’s power are related; you can increase the intensity of the flash depending upon your distance from the subject. You can increase the pop up flash output power using the Flash exposure compensation (FEC). And there are two kinds of external flashes – manual power flashes and automatic power flashes. The latter adjusts its output power depends on the exposure you set and in the former, you have to adjust the power by yourself.
- How to control the intensity of light from the flash?
The quality of light is very important when you use fill flash otherwise it will make your images washed out/flat. A solution is to diffuse the light. One can diffuse the light using a myriad of ways – softboxes, diffusers, shooting through/or against an umbrella etc. Usually, flashlight gives a blue tone to the image. You can fix this by using various gels in front of the flash. For example, an orange gel along with the flash will help you to get a proper skin tone.
So, that’s it. These are the important factors you should consider before using fill flash. I hope you are ready to use your flash for some fill flash photography. The most important thing you should do inorder to achieve good results is to experiment a lot with your flash. Try different flash intensities and figure out how to change it depending on your subject’s distance.
Fill Flash Photography Technique (Step by step guide)
Let’s do this technique now.
Fill flash is not Full flash. Full flash is normally used during the night and very low light situations. In full flash photography, the main light source is flash itself. While in fill flash photography, the flash is used to fill the shadows.
So when you have a strong backlight or the subject is in shadows, you can use fill flash to fill the shadows with light.
- Expose for bright areas or background
The above picture of sunflower is a high dynamic range scene. This photo is taken by exposing for the background as the background is brighter than the subject. This makes the subject dark (or in shadows). If you adjust the exposure to make the sunflower brighter, the background will be over-exposed (no details in the sky) . So, [one of] the solutions for getting a proper exposure is make a double exposure. i.e.
- Use flash to light up the flower/fill the shadow areas with your flash — Exposure #1
- Properly expose for the background — Exposure #2
So I used my external flash on low power and filled the shadows on the flower with the flash light. And here is the result:
As you can see, now the image is properly exposed — both for the background and for the foreground. Here, I fired my external flash from the left side of the camera to properly fill shadows. So you have to target the light to the shadows areas. You will find it very useful while taking portraits.
From this example, I hope you have got an idea about how to use a fill flash. If you have any queries, drop them as comments.
As a rule of thumb you can say that the “shutter speed only affects the ambient light and has no contribution to flash exposure”. To get the best result using flash initially set the shutter speed for ambient light and then fiddle with the iso or aperture.
The exposure triangle — ISO, aperture, shutter speed — only contributes to the second exposure I mentioned. I mean, for the best results, you need to set a proper output power for the flash.