Tuesday, 7 August 2012

Fill Flash

What is Fill Flash?

Fill flash is a technique used by photographers to brighten up shadow areas when shooting under conditions in which the background is significantly brighter than the subject being photographed.

Fill Flash
Photo By Chemisti

 In fill flash situation the flash is not acting as the main light source for the image. The main light source may be sunlight or any other artificial light source. The exposure for the scene is also made to expose for the main light. Flash is merely used to reduce contrast in the scene and to bring out details in the shadow areas.

When to Use Fill Flash?

Fill flash is most useful when photographing subjects under direct sunlight, when dealing with backlit subjects, in low light situation and is also useful for adding catch light to the subject’s eyes etc.

Fill Flash
Photo By Jaimito Cartero

When photographing in direct sunlight there will be almost always be shadows in areas such as under the eyes, noses, chins etc. the situation is even worse when the subject is wearing a hat. Fill flash will help eliminate those shadows and will also help create the catch lights in the subject’s eyes there by giving them life. Fill flash could also be used will slow shutter speeds in low light situations where the flash determines the exposure or aperture and shutter speed determines the background exposure. It is also a widely used technique in Nature photography and also in Macro photography.

When Not to Use Fill Flash?

Fill flash should not be used when working with low key images in which you purposefully decide to keep the shadow areas dark. Similarly when attempting to capture the mood of the scene like the effect created on a subject by the golden light during the early morning or late evening hours fill flash is not suitable. And if you are shooting a subject that in itself is a lower power light source than your flash; for example hot coal or fire, fill flash is not to be used.

Fill Flash
Photo By Purplemattfish

Subject to flash distance is one other factor that determines whether it is proper to use fill flash in a scene. If the subject to flash distance is more (more than 6 to 8 feet – depending upon the flash’s guide number) you will not be able to get enough light over to the subject even will the flash operating at full power and all other variables optimized.

How to Set Up Fill Flash?

Modern day DSLR cameras and TTL flashes makes using fill flash so very easy that many beginners to photography may have used it already – UN Knowingly. In new generation cameras if the flash is turned on when there is sufficient ambient light available on the scene; the flash is automatically set to operate as fill flash. Cool …. Ha.

Fill Flash
Photo By Martin Raab

Wait… there is more…. The chips inside of the camera and the flash are so smart that they not only command the flash to act as fill but also set the required Flash Exposure Compensation automatically. The Flash exposure compensation automatically applied by the camera is however not indicated to the photographer, who is then free to set his own compensation values depending on his personal taste of contrast levels. The compensation thus added by the photographer is also applied in addition to that set by the camera.

How to set your DSLR to provide Automatic Fill Flash?

Fill Flash
Photo By Dustin Diaz

In case of Canon DSLRS set the ETTL flash metering to “Evaluative” through the camera custom functions.

In case of Nikon set the flash metering system on the flash to “TTL BL”
How to set your DSLR to provide Standard Flash Instead of Fill Flash

If you would like to override the camera settings for automatic fill flash and decide to apply whatever compensations needed manually:-

Canon – In Camera Custom Functions set the flash metering system to “Average”

Nikon – In the flash set the mode to “TTL”

Fill Flash
Photo By Severin Sadjina

However it should be noted that when set to give standard flash exposures the effect of flash will be prominent in the images as the camera is prevented from applying automatic compensations depending on the subject and background brightness. As a result shots could be overexposed and highlights clipped. So use your histogram in addition to visual clues from the LCD to get your compensation values right.

In the next article we will discuss about Photography - Lighting - Flash - Understanding TTL Flash – Stroboscopic Flash Photography 

Related Reading

  1.   Understanding TTL Flash – Flash Terminology, Anatomy, Functions and Features
  2. Slow Sync Flash
  3. How to Trigger your Off Camera Flash
  4. Focal Plane Shutter
  5. High Speed Flash Synchronization