Taking Balanced Exposures Using Fill Flash

Introduction to Fill Flash

I am often encounter scenes containing a range of brightness greater than my camera is able to capture in a single shot. At other times the camera may be able to capture the range but I have to make a choice where the subject is optimally exposed and the background is overexposed. A typical example of this is shooting a portrait of a subject in shade with a bright sky or landscape in the background. Another would be photographing a subject on a beach with a beautiful sunset in the background.

Though you might correct for these deficiencies with High Dynamic Range (HDR) techniques in camera or during post processing, or by manipulating the exposure curve in software the results may look less appealing. Using fill flash for the shot will often improve the outcome by correctly exposing both the subject and the background at the time the shot is taken.

For this post I assume that you are familiar with basic terminology used in photography, your camera and flash controls and the basic use of flash photography. I am shooting with a Nikon D700 and an SB-800 flash. Your equipment may not have the same settings or may use different terminology.

Tools Used in this Post

Here are the tools I used to create the images in this post.

  • Nikon D700 DSLR body
  • Nikon Speedlight SB-800 flash (popup flash often works as well)
  • Small flash softbox
  • Nikon AF S NIKKOR 28-70mm 1:2.8 D lens
  • B+W 77 KSM C – POL MRC Circular Polarizer filter
  • Gitzo tripod

How a Camera Determines Exposure

In simple terms, a camera sets an exposure based upon the brightness of the different elements in the scene, assuming you are shooting in Matrix Metering mode. The camera’s light meter performs a calculation based upon the tones in the scene from darkest to brightest in order to properly expose those areas that are closest to the middle of the scene’s tonal range – the mid-tones. Some cameras also contain databases of known scenes that assist the meter in making its exposure decision.

When shooting in Program mode the metering output translates into shutter speed and an aperture values, say 1/200th of a second at f/7. I shoot the majority of the time in Aperture mode where I set the f-stop to give me artistic control over depth-of-field allowing the camera to set only the shutter speed. So, for the rest of this post I will assume Aperture mode unless stated otherwise.

With the exception of in-camera HDR, the camera can only make one exposure regardless of the tonal or dynamic range of the image.

Different metering modes use different exposure calculations, thus changing the exposure value.

Metering Modes in Depth

Cameras generally have three metering modes, with each manufacturer building in proprietary exposure algorithms such as the scene detection capability I mentioned earlier. These are:

  • Matrix ( Nikon)/Evaluative (Canon)
  • Center-Weighted
  • Spot

Let’s examine each of these.

Matrix Metering

Matrix Metering Control

The Matrix Metering symbol on my Nikon D700 is the center symbol in the above image. Using matrix metering, the in-camera light meter examines the entire scene in sections, placing additional importance on the area of focus. Using proprietary methods it ‘averages’ the different tones to arrive at what it believes is an optimal shutter speed value. This works well for many subjects and scenes but often has trouble when large dynamic ranges are involved. Also, you may not like the meter’s decision because it might under or overexpose your intended subject or the background.

Regardless of its shortcomings I shoot predominantly using matrix metering because it works so well in most cases.

Center-Weighted Metering

Center Weighted Metering Control

The Center-Weighted Metering symbol is the right-hand symbol in the above image. Like matrix metering, center-weighted metering also examines the entire scene but gives great importance to the area within the circular area that falls under the focal point you select, more so than in matrix metering. You can set the size of this center weighting circle in the D700’s menu.

Center-weighted metering is useful when you want to give exposure priority to more than just a spot on the background and I use it from time to time.

Spot Metering

Spot Metering Control

The Spot Metering symbol is the left-hand symbol in the above image. Spot metering is exactly as it sounds. The light meter examines only the brightness of the scene falling under the tiny focusing spot in your camera’s display. With spot metering you can force the camera to expose for a very particular tone in the scene, ensuring the tone lies at the midpoint in the images luminosity curve, i.e. the mid-tone.

Spot metering is very useful when employing fill flash and I frequently use it for this purpose.

Using Fill Flash

Fill flash allows you to correctly expose more than one element in a scene with a large dynamic range, typically the subject and the background. Because the camera can only set one exposure, controlled by the shutter speed you must expose for one element and add light for the second. In our introductory examples the subject is darker than the background so I would spot meter and expose for the background and use fill flash on the subject. Cameras can automatically adjust the flash for the subject that you focus on using Through the Lens (TTL) flash metering.

High Speed Sync

I often use an externally mounted flash, the SB-800 because it allows for faster shutter speeds than the popup flash. Nikon calls this FP Auto High Speed Sync, or high speed sync for short.

Using high speed sync with my Nikon D700 and Nikon Speedlight SB-800 I am able to synchronize the flash to shutter speeds all the way up to the highest shutter speed the camera is capable of. This allows me to correctly expose very bright backgrounds such as a daytime sky using short exposures, e.g. 1/1000 second and still use fill flash on the subject.

Fill Flash Methods

There are three fairly simple methods for using fill flash where the subject is much darker than the background. They are:

  • Point and Shoot
  • AE-L (AutoExposure-Lock) button
  • Manual Exposure

Point and Shoot

This is the quickest and easiest method for using fill flash.

  1. Pop up or mount your flash
  2. Set your camera to matrix exposure mode
  3. Set your aperture for the desired depth of field
  4. Put the subject under the focus point
  5. Press the shutter release button

Now that was easy, wasn’t it? Many times this is all you need to achieve great results. The combination of the camera’s matrix metering and TTL metered flash automatically exposes for the background and adds just enough fill flash to properly illuminate the subject. When setting up for this shot as when using the remaining two methods the subject must be within the range of the flash and the background needs to be out of the flash’s range.

What if the exposure still isn’t as you would like. That is when using the compensation methods described later or one of the next two methods may be useful.

Note, if you are shooting against a background where the meter indicates a shutter speed slower than the minimum flash sync speed, typically 1/60th of a second you can adjust for this in a number of ways. The easiest is to set the camera’s flash to Slow Rear Sync mode. Alternately you can set the camera’s Flash Shutter Speed to a value below that required for the background exposure, e.g. 2 seconds. Alternatively you can increase the camera’s ISO value so that the shutter speed for the background exposure increases above 1/60th of a second. You can also use the Manual mode described below.

AE-L Button Method

Fill Flash - AE-L Button

This is the second quickest method after Point-and-Shoot when using fill flash on the fly. The AE-L button allows you to meter a portion of the scene, and hold the resultant shutter speed while using flash to expose the subject.

  1. Popup or mount your flash
  2. Set your camera to center-weighted or spot metering
  3. Set your aperture for the desired depth of field
  4. Point the focus point at a mid-tone in the background
  5. Press and hold the AE-L button (Note: Some cameras allow you to set this button so that once pressed it holds by itself, resetting after you press the shutter release)
  6. Reframe your subject so that the focus point is on the subject
  7. Press the shutter release

Note that if your camera’s maximum sync shutter speed for the pop-up flash is not sufficient to properly expose a bright background, e.g. 1/250th of a second you will need to mount an external flash that can sync at the necessary shutter speed, e.g. 1/500th of a second. This typically happens when the background is very bright, e.g. the sky when compared to the subject.

The Manual Mode Exposure Method

This method is similar to the AE-L button with the exception that you will have to manually set the shutter speed based upon the metered background. Manual mode is useful if you are taking multiple shots in that you can set the shutter speed once at the beginning of the session eliminating the need to spot meter the background for each shot with the same subject and background.

  1. Popup or mount your flash
  2. Set your camera to center-weighted or spot metering
  3. In aperture mode, set your aperture for the desired depth of field
  4. Point the focus point at a point in the background you want correctly exposed, e.g. the sky
  5. Read the shutter speed in the eyepiece display
  6. Switch the camera to manual mode
  7. Set the shutter speed to the value you read
  8. Set the same aperture you metered with
  9. Reframe your subject so that the focus point is on the subject
  10. Press the shutter release

The result should be identical to that obtained in the AE-L Button method.

I should note that you can also adjust the shutter speed in manual mode using the in-eyepiece light meter indicator but that is beyond the scope of this post.

Optimizing the Exposure

Hopefully your camera’s metering and flash created an exposure that is pleasing to you regardless of the method you used. But what if it didn’t? What can you do if you still don’t achieve the desired background and subject exposures? This is where the exposure and flash compensation settings come into play. These can be used with any of the three methods I laid out.

Exposure Compensation

Exposure Compensation Button.jpg

The Nikon D700 Exposure Compensation button in the image above, accompanied by the rear thumbwheel sets exposure compensation measured in ‘stops’. It has the effect of increasing or decreasing the shutter speed. If, for example your background is slightly overexposed you can use the exposure compensation setting to decrease the exposure by 1/2 or more stops. Try this and you will see that you are indirectly changing the shutter speed. Of course, if you are shooting in manual mode you can simply adjust your shutter speed directly. Importantly, this does not affect your fill flash. It still uses TTL metering to shine the correct amount of light on the subject.

Flash Compensation

Flash Compensation Button.jpg

The Nikon D700 Flash Compensation button in the image above, accompanied by the front finger wheel sets flash compensation also measured in ‘stops’. Setting flash compensation values on the camera or on the external flash increases or decreases the amount of light the flash produces. For example, if your subject is too bright, simple decrease the flash using the compensation setting. This has no effect on the shutter speed, so your background exposure will not change.

Sample Shoot

Here is an example of using fill flash to illuminate a floral arrangement in the shade while correctly exposing the bright scene behind it. They are straight from the camera with no image manipulation.

The first image is the result of using matrix metering for the exposure. At an aperture of f/8, matrix metering set a shutter speed of 1/20th of a second, attempting to balance both the sky and trees in the background with the floral arrangement. Clearly matrix metering is inadequate for this shot as the sky is nearly blown out and the flowers too dark.

Matrix Meter Scene Matrix Metered Exposure

I created the next image by spot metering the sky using the AE-L button then focusing the camera on the flowers prior to pressing the shutter release. I have set my camera to lock the AE-L button, meaning that I push it to meter the sky and it retains that setting until after I press the shutter release button. Spot metering the sky set the shutter speed to 1/180th of a second. I included this image only to illustrate the results of  spot metering. You can skip taking this shot going directly to the one metered for the sky and using fill flash.

Spot Meter Sky

Spot Metering the Sky

Finally, I created this image by again spot metering the sky, resulting in the 1/180th of a second exposure as described for the image above, refocusing on the flowers and using fill flash to brighten the flowers. In this case I liked the tonal balance of the scene and I did not need to use exposure or flash compensation.

Spot Meter Sky with Fill Flash

Spot Metering the Sky with Fill Flash


Hopefully, this post has demystified the use of fill flash. In reality, it is pretty straight forward. Expose for the background and use fill flash for the subject. Use exposure and flash compensation to adjust the brightness of the background and subject according to your tastes. With creative use of these techniques you can correctly expose other scenes such as a room with a lit lamp in the scene – expose for the lamp and fill the background; night time portraits with city lights in the distance – expose for the cityscape and fill the subject; indoor shots with windows in the background – expose for the scene outside the window and fill the indoor subject with flash.

Thanks for reading this post. If you have any questions please ask them in the comments.

Happy shooting!


Copyright Notice

© Michael J. O’Connell, 2017. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Michael J. O’Connell and this blog with appropriate and specific direction to the original content.

This entry was published on May 27, 2017 at 6:14 PM. It’s filed under Flash Photography, Photography Tips and tagged , , , . Bookmark the permalink. Follow any comments here with the RSS feed for this post.

2 thoughts on “Taking Balanced Exposures Using Fill Flash

  1. Larry James on said:

    Thank you, I will check it out.One can never learn enough. I have been using reflectors to fill but the fill flash is always handy and convient. Hope all is well. Hello to Linda.

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