"Fill flash has to be one of the best kept secrets in photography. After reading about it here, I used it and wow, what a difference!"
"Filling an area with Flash" is one of the key features in the world of Digital Flash Photography. We will focus on exploring two specific areas of this topic:
What is it?
Why is it important (in my selection of a digital camera)?
What is Fill Flash?
The big "F-F" is not a feature of digital cameras as much as it is a photographic technique.
As far as features, you want to know whether the digital camera in question has the capability of using the flash when YOU want to rather than ONLY when the camera automatically decides (for you).
Whether your digital camera has a built-in flash or a
hot shoe
(a hot shoe provides the capability of using an external flash), think of fill flash as the ability for YOU to decide WHEN AND HOW to use the flash.
Most people don't think about the flash. When it's dark, the flash is used (either automatically or by choice, depending on the camera). When it's light (outdoors, that is), it's not used.
But, there are situations when you may want to use the flash when it's not required strictly due to darkness. When done at these times, it is considered to be fill flash. When used properly, your outdoor photos will benefit, since the purpose of fill flash is to reduce shadows and balance out the light on the subject.
Normally, a camera/flash unit will automatically determine the proper amount of light that the flash emits. However, when used as fill flash, it is better to be able to manually control the amount of light that the camera emits. Cameras that have this ability perform what is called flash exposure compensation.
Why is this important?
When photographing subjects outdoors, many factors influence the amount and type of light you are working with.
A few of the key ones are:
Time of day
Climate
Relative position of the sun
Sky conditions.
Fill flash is a technique that allows you to take good pictures in spite of less-than-ideal lighting conditions.
Bottom line, by using fill flash, a controlled (reduced) amount of light is added to the natural outdoor light, thus filling in shadows and reducing contrast.
For most outdoor photos, the subject is in front of the photographer while the light source (usually the sun) is behind the photographer somewhere between 20 degrees and 70 degrees off the horizontal plane.
In that situation, the subject is generally lit just fine, and no fill-flash is required.
However, when the sun is directly overhead (90 degrees off the horizontal plane), such as with these golfers, shadows will result. Eyes will be partially in shadow and areas below the nose will be affected by the shadow caused by the nose. Technically, the term is called "snout-us moredark-us" which is Latin for "watch out if you have a big nose."
If anyone is wearing a hat, the situation is even worse because the brim of the hat casts a larger shadow. In this case, the two men have their faces covered by strong shadows, while the women are less affected.
This is prime time for using fill-flash. Had it been used in this image, everyone's face would be nicely visible, but then the picture couldn't be used as an example of what not to do.
Here are specific suggestions for what to do if you find yourself in this type of situation:
Manually activate your camera's flash.
Make sure you are close enough to your subject so that the flash will have an effect (check your owner's manual for what is the effective range of your flash).
Now we experiment. Take one (or more) test shot with the flash exposure compensation value set at each of these values: -1/3, -2/3, -1 stops.
Examine the resulting images (by checking the histogram and LCD display) and when you find one where you are happy with the overall resulting contrast and light/shadow effect, use that flash exposure compensation value.
By using your flash in this manner, you produce additional light on the subject. Therefore, the overall photograph can be better metered and thus better exposed.
Another common use for Fill Flash is to provide more pop to your subjects' colors when photographing on an overcast day. Although it may seem silly to use a flash outside, during the day, after observing the results, you'll be glad you used it.
This video on flash photography should shed some light on the subject...