How to use Fill Flash:

When the sun is out, I highly recommend filling the dark shadows on people’s faces outdoors by forcing the Flash to fire, or turning on Night Mode with Flash, or popping up the flash ready to fire. This technique is called fill flash. Have people take off their sunglasses so you can see their soulful eyes. Try to place people with their backs or sides to the sun or in the shade so they don't squint. After shooting, zoom into the camera's LCD or EVF to make sure the image is focused and everyone's eyes are open. Some cameras let you increase or decrease flash compensation to more naturally balance with ambient or background light.

Beware the following pitfalls when using fill flash:

• Using fill flash in sunny outdoors light will often overexpose the image, losing details in the brightest areas − check the image (and its histogram bell curve) in the LCD.
  
• Workaround: Manually set your lowest ISO speed setting (such as ISO 100 or 50) and reshoot. Or turn off flash and reshoot. [Or use an SLR or camera which supports faster "flash synchronization" speeds. Or turn on or add a ND (Neutral Density) filter.] 
• Technical details: In your camera's users guide, check your camera’s fastest shutter speed when using Flash (which on my Canon Powershot Pro1 is 1/250th of a second). If on bright sunny days when forcing fill Flash, and the camera automatically goes no higher than say 1/250 second, then shots may overexpose, even at the highest f/ stop.
  
• Canon Powershot Pro1 users note: If the subject is also sunlit, Flash forces images to look too warmly red (it forces White Balance=Flash), so I recommend to save in RAW; then you can easily readjust Color Temperature (or White Balance) later in RAW Converter. / The Menu in the Pro1 lets you turn on a handy 3-stop ND Filter, which is great for photographing flowing water, or for using Fill Flash in bright sunlight.
  
• Most built-in flashes cannot reach subjects beyond 10 to 20 feet away. Flash won't brighten subjects which are too far away. Read your camera's users guide, and write down & memorize how far your flash can reach: ______ feet/meters at wide (W) zoom, and ______ feet/meters at telephoto (T), at ISO setting _______.
  
• Using flash can quickly run down your camera battery, so keep a fully charged spare battery in your pocket.

Fill flash for low light conditions, indoor or night subjects:

• If you have Slow Synchro Flash...Off, as is the default on most cameras, the subject's action within flash range will be sharpely frozen, and the background will be darker (beyond flash range) when indoors or at night.
  
• Turning on Slow Synchro…On or Night Mode lets you flash at shutter speeds slower than about 1/60 second, which can magically balance the flash with ambient (available) light for outdoor evening portraits or to make fun blurring effects. For sharper hand-held Slow Synchro Flash shots, steady the camera against something solid, or use a tripod.
• As an example, on the Canon Powershot Pro1, to use Flash with an exposure less than 1/60^th second, you must set Night Mode or Slow Synchro Flash...On , which is available when flash is popped up in Av, P, Landscape, or Panorama mode.

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For Advanced Photographers: How to Optimize Shadows and Highlights

The above image illustrates how to optimize shadows and highlights, after properly exposing the highlights at shooting time. When you expose properly to capture highlight details (such as in the bright clouds and glacier), unfortunately most cameras will by default overly darken & dull the shadow detail (as shown in the second image). This undesirable darkening happens for most cameras, no matter whether you shoot film, digital RAW or JPEG. One way to work around the darkening is to balance the exposure with a neutral-density graduated filter over the lens at shooting time, which I did back when I shot film (before 2004). However, now that I shoot a digital camera, RAW files retain enough shadow detail so that I have greatly reduced my use of a graduated filter over the lens. I used Adobe Photoshop to revive the shadowy flowers of the second image to be more naturally vibrant as shown in the first image.
     Editing to optimize the image lets me recreate the accuracy and emotional impact of what my eyes saw at shooting time as shown in the first image. Bright detail in the magenta flowers can now be seen simultaneously with detail in the white clouds.

Advantages of shooting digital RAW mode: 

• Using digital RAW files makes photography easier & better than when shooting film. If your goal is to make larger prints with better detail in both shadows and highlights, RAW files give much extra optimizing/editing headroom, with no posterization (wikipedia link).
  
• With a digital camera shooting in RAW mode, I no longer bother with a neutral-density graduated filter over the lens (which was required when using film). Instead, I use a "neutral-density graduated mask", as described in the "How to" box below. Caution: digital camera shadow areas are much more subject to posterization than highlights, so expose to the right of your histogram without overexposing. Using a neutral-density graduated filter over the lens will still help balance many digital shots, such as a bright sky with darker landscape, and will retain more accurate shadow detail. See also my notes on digital noise.
  
• Many advanced digital cameras allow you to save images in RAW file format. RAW files capture an f/stop or two of better dynamic range in highlights and shadows, and 16 times the color accuracy, when compared to JPEG format. 
• The great color accuracy of RAW gives you much greater editing headroom than JPG, thus eliminating the risk of posterization (wikipedia link) when using JPG files.
  
• Dynamic range, measured from the brightest highlights to darkest shadows, seems to be about 7 or 8 f/stops when recovered using RAW Converter software. In my experience, the dynamic range of RAW is slightly better than print film, and much better than slide film.
• Typical RAW files have 12-bit color accuracy, versus only 8 bits for JPG. In binary, this 4 bit difference equals 2 to the power of 4, or 16 times more accuracy.
• For best RAW results:  Optimize as much as possible in your RAW Converter program (optimize white balance, exposure, Curves, and so forth), such as Adobe Lightroom 2.x. If you will be editing files extensively for printing, convert RAW using a Color Space of Prophoto or Adobe RGB. Convert the RAW to a 16-bit TIF file, and edit shadows and highlights using a "digital graduated filter" or "neutral density graduated mask" as described below. Don't sharpen the image until after the final step of resizing a copy for printing or web display.

How to use a Digital Graduated Filter How to optimize the shadows and highlights in a digital image file (JPEG, TIF or RAW). Part I In the following three Figures, I illustrate how to adjust image tone and to apply a digital Graduated Filter or Adjustment Brush in Adobe Lightroom version 2.3. The general principles also apply to most other image editing programs. Figure 1 shows the original image as shot and saved in RAW format (Nikon .NEF file). Notice the colorful histogram in the upper right of the Develop module of Adobe Lightroom version 2.x. The histogram data piles up against the far right, indicating that the whitest and brightest areas of the image are overexposed and truncated. Luckily on DSLR cameras, RAW files let you recover at least a stop of overexposure.      Normally I just move the Exposure slider leftwards (to darken) and/or the Recovery slider rightwards to recover the data in the overexposed areas (which would have been irrecoverably truncated if I had shot the file as JPEG.) But if you are in a hurry, just click the Auto Tone button (circled in pink in Figure 2). Figure 1 (above):  I photographed this image within the Ecuadorian national park of Reserva Geobotánica Pululahua in April 2009. Pululagua (or Pululahua) is a dormant volcano in the north of Quito, Ecuador. Figure 2 (below) shows the effect of pressing Auto Tone (in this case a subtle effect; other times great in improvement, but sometimes ugly). Auto Tone automatically adjusts Exposure, Recovery, Blacks, Brightness and Contrast. In this image, increasing Recovery to 23 and decreasing Contrast to 18 recovered all of the truncated highlight data. Also, blacks darkened from 5 to 12. Mid tone Brightness was shifted darker (from 50 to 46).      If you don't like the automatic result of Auto Tone, choose Edit>Undo (or CTRL+Z in Microsoft Windows) (or Reset All for that image in the Library module), then adjust sliders individually. Figure 3 (below): Now click the Graduated Filter tool icon just below the histogram (shown boxed in pink) (or press G). A box will drop down a set of six sliders as shown (or buttons). You can toggle between slider mode (much preferred) and +/- button mode by clicking the light/dark pair of squares just below the word "Edit".... ...In this image, I brightened the foreground by adjusting the sliders as follows: brighten Exposure to +1.2 stops, Contrast to +47, and Clarity to +18 (which can be set before or after drawing the Graduated Filter).      Drag to draw the transition area of the Graduated Filter onto the image. Where you first click the mouse is zero effect, and the point where you release the mouse button after dragging is 100% filter effect. Three parallel hairlines appear on the image showing the starting, middle, and stopping points from your mouse drag. When you hover the mouse over the middle hairline (away from the center dot), the mouse turns into a curved double headed arrow which allows you to grab and rotate the Graduated Filter, such as to line up with the mountain horizon. To shrink or enlarge the transition area of the Graduated Filter, grab the top or bottom hairline and drag. You can grab and drag the middle line's center dot (circled in pink) to move the whole filter.      You can add multiple Filters to the image (just like Layers in Photoshop, but easier)! To modify settings of each filter, you must first select the center dot which turns black (indicating selected/active). The Delete key will remove a selected filter. (Warning: watch out if you press H by mistake, which toggles the appearance or confusing disappearance of the dots marking locations of Graduated Filters.)      If the Graduated Filter tool doesn't line up correctly with parts of image, simply draw using the Adjustment Brush tool, which looks like a paintbrush and can draw your "filter" (mask) to any shape! Use your mouse scroll wheel (if any) to quickly change the brush size. To erase previously Brushed areas, hold down the ALT key while drawing, which makes the circular cursor label change from + (plus) to - (minus). To see a red mask indicating the affected area that you drew for the Adjustment Brush, hover the mouse pointer over over its active black (selected) dot. Want to learn more? Part II below explains how to use Layers in Adobe Photoshop to create a digital graduated filter. Part II also repeats how to more easily achieve the same thing in Adobe Lightroom (as illustrated with pictures in Part I): Part II Below I generally describe how to use a "digital graduated filter" or "neutral-density graduated mask" in Adobe Photoshop or Lightroom: My goal is to make an image that portrays what I saw and felt. Unfortunately, most cameras poorly capture the total range of light from bright to dark in a sunlit subject that includes shadows. In comparison, your eyes can quickly perceive subjects in dark shadows in great detail simultaneously with brightly lit areas. As a workaround, I suggest using a "digital graduated filter" or "neutral-density graduated mask" to separately optimize the areas of shadows and highlights in your image. Most commonly, I like to separately optimize the sky and foreground of a landscape image. First I digitally select the dark foreground (all except the sky) of the image. Then I adjust its white point, mid tone level, black point, color saturation and Clarity (local contrast). Then I digitally select the bright sky and optimize with different filter settings. Each distinctive tonal area of the image should be adjusted separately. (The term "mask" refers to the part of the image which is excluded from the filter settings.) In 2008, I was glad to see new cameras introducing shadow brightening while preserving highlights, and also expanded dynamic range, to better emulate how eyes see. However, these features usually only apply to JPEG shots, so you still need the techniques below when optimizing RAW file images. Shooting RAW is much better than shooting JPG if you plan to optimize/edit the image. Always properly expose the highlights at at shooting time. Make sure the shot is well-exposed by maximizing the area under the bell-curve of the histogram. The camera's handy histogram displays brightness values from 0 to 255 from left to right. Expose brightly enough to push the histogram curve as far as possible to the right, making sure that it flattens to zero at brightness value 255, without truncation against the right side. Overexposed JPEG files cannot recover highlight detail. Any subject that is overexposed (brighter than 255) in a JPEG file will be truncated at brightness level 255, thus losing highlight information. Thankfully, RAW Converter software can recover an additional f/ stop of highlight information brighter than 255 from DSLR RAW files (or about half a stop for compact, small-sensor camera RAW files) and rebuild the smooth histogram 0 to 255 using image data from improved dynamic range. You can also recover a similar amount of tonal information in the shadows/blacks while controlling random noise! I advise doing all your tonal editing in RAW files (or 16-bit TIF files exported from RAW) in order to avoid posterization (wikipedia link). You can revive many JPEG shots, but in big enlargements, the quality can be noticeably worse than when derived from RAW & 16-bit TIF. Do as much of your editing as possible on the RAW file itself using a great program such as Adobe Lightroom (or similar Apple Aperture; or freebie FastStone.org). For further editing, you may also need to output a 16-bit TIF file (using RAW Converter software using Adobe Photoshop, or your camera's RAW software provided on CD, or other program). Or you can edit JPEG files if that's all you shot, but watch out for posterization (wikipedia link). On your computer, run any photo editing software that supports Selections or Layers (such as Adobe Lightroom 2 or Photoshop). Open the RAW, TIF or JPG file. (To avoid compression losses each time you save a JPG file, save the original JPG image file as a non-lossy TIF, and edit just the TIF.) Shadows (or foreground) adjustment: Select just the shadows plus non-sky midtones, excluding the sky: Using Adobe Lightroom 2: Lightroom is much quicker and easier than Adobe Photoshop while achieving similar excellent results (except Photoshop is better for preparing images for printing sRGB format or for pre-press CMYK). Under the Develop tab, select the shadows plus non-sky mid tones (excluding the sky) in the image by dragging/drawing a Graduated Filter (and tilt as needed) or a very large Adjustment Brush. Then adjust Exposure (shifts the whole histogram brighter or darker), Brightness (shifts just the mid tones, keeping the brightest and darkest values constant), Contrast (widens or compresses histogram), Saturation (intensifies color purity), and Clarity (increases local contrast to better define large edges and shapes; very useful on almost every shot!). In the same way, select and adjust the highlights (bright areas such as the sky) in the image by dragging/drawing another Graduated Filter or very large Adjustment Brush.  Or using Adobe Photoshop: Create a Levels Layer (Layer>New Adjustment Layer>Levels...). On this new Levels Layer, draw a black mask over the sky using the Gradient tool. Or click the Quick Mask button, and draw using the Brush Tool (set to a very big soft-edged Airbrush with color reset to black). Slide the the white value end-point slider ("256" level) to the left in the Levels 1 histogram until you almost start cutting off the right edge of the bell curve. This sets the white point and lightens your shadow selection. Adjust the mid tone slider in the Levels 1 histogram, making the image darker or lighter as needed to match what your eyes saw in reality. Don't overdo it. Readjust steps 4 and 5 as needed, since they affect each other. (Often an additional Curves Layer will do a better job of balancing mid tones.) Slide the black value end-point slider ("0" level) to the right in the Levels 1 histogram until you start cutting off the left edge of the bell curve, or as needed to match what your eyes saw in reality. Readjust the black point, mid tone and white point sliders as needed, since their interaction changes image appearance. Don't overdo it. Watch out for posterization (wikipedia link). Highlights (or sky) adjustment: using Adobe Lightroom 2: use same technique as step 5 for shadows above. using Adobe Photoshop:  Invert the above shadows/mid tones selection to make a new Levels Layer for the highlights selection, as follows in Adobe Photoshop: Select>Load Selection>"Channel: Levels 1 Mask". Then choose Select>Inverse. Then choose Layer>New Adjustment Layer>Levels.... This makes Levels 2, for the highlights. Move the black value end-point slider ("0" level) to the right in the Levels 2 histogram until you start cutting off the left edge of the bell curve. This sets the black point and darkens the highlights. Adjust the mid tone slider darker or lighter as needed to match what your eyes saw in reality. Be careful to keep the sky/highlights looking natural. I usually avoid adjusting the white value end-point slider "256" level) for the highlight selection (Levels 2). Congratulations, you have now learned an advanced secret for adding greater emotional impact to your pictures.

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