Lighting: Using a pop-up flash

Recently, someone asked me to write an article for this blog on how to use pop-up flash to obtain natural looking photos.  I have to admit that I do not use a pop-up flash very often due to its limitations.  For one thing, it has a short range, usually around 12'.  But worse than that, it is positioned on the camera so the light it throws is very harsh and directional, and casts hard shadows.  This last feature is worsened when the camera is turned vertical so the shadow falls off to one side of the subject instead of down and behind where can be hidden.  Nonetheless, I thought the project would be interesting to explore so here it is.

The real trick to using on-camera, pop-up flash correctly is in not allowing it to dominate the scene.  When used as the major light source, the flash creates an artificial, flat, and overly bright light that destroys the natural ambiance of the scene.  What we are going to try to do here is look at methods of applying the flash to enhance the naturally lit scene rather than dominate it.

Let's examine some of the uses for on-camera flash as an auxiliary light source.

Outdoor fill flash:

It might seem counter intuitive to use a flash outdoors on a sunny day, but this is a situation that can benefit the most.  Harsh shadows on the face from a strong overhead sun can ruin an outdoor portrait.  The difference in exposure between the bright highlights and deep shadows is so great that important detail may be lost in one or both areas.  There are two ways of dealing with this, both involve what is known as "fill flash".  When the subject is facing into the sun, flash fill can be used to brighten the shadows and equalize the exposure between them and the highlights.

Harsh shadows on a sunny day can ruin an outdoor portrait.  Popping up the on-camera flash to fill in the shadows with extra light results in a much more flattering look.  Most cameras can handle this by placing them in TTL flash mode.

 Light from most built-in flash units are of very low power so you may need to use them in close to achieve full benefit.  Over powering the sun is no small task.

A better solution for an outdoor portrait might be to turn the person to face away from the sun.  This puts them in a back lit situation, which is much easier to fill, and often more flattering.

Positioning the subject with the sun behind them results in a very flattering back lit scene.  Using the on-camera flash here adds more detail to the face and a catch light to sparkle the eyes.

Outdoor flash fill situations are usually very bright so determining proper exposure is primarily a matter of using your normal camera exposure, setting the flash on TTL, and allowing the camera/flash derive its own output.  Working in the manual setting you can select the correct exposure reading for the overall scene.  You don't have to worry about the shadows because this is the area that the flash is filling to bring its exposure up to the level of the overall scene.

You will need to check to see that you are not inadvertently overexposing the scene.  Most cameras have an upper shutter speed limit at which a flash can be used.  This may not be high enough to properly expose the scene.  Often this is a result of the ISO being set to high, or may be a result of trying to use a lens aperture setting that is too open.  

Indoor flash fill: 

Indoor flash fill is usually not as necessary as outdoor fill, but it may add clarity and detail to the subject.  In addition, it will add a flattering "catch light" in the subjects eyes.  Catch light is the bright dot of light that is reflected in the subjects eyes making them sparkle.

An indoor situation that might require flash fill would be one where the available light is sufficient to take the picture, but the shadow exposure is beyond the range of an overall even exposure.  Filling the shadows with light is similar to outdoor flash fill, although a major difference, light intensity, will likely be much less and may lead to overexposing the subject.  Care must be taken to achieve an overall even exposure that does not washout the background.

Even though you can take a photo indoors without a flash, you may want to add it to create a more even, flattering light.

Slow synch flash:

This technique is used when the background scene is very dark relative to the foreground subject, as with a person photographed against a night city scene, or a person photographed indoors where the scene is quite dark.  Slow synch derives its name from the slow shutter speed necessary to allow the background to record more naturally in the photograph.  Typically, on most cameras, particularly when using them in auto setting, the flash is synchronized to a shutter speed between 1/60 - 1/250 second.  The flash will only function at a speed slower that this synch speed, and the camera tries to use the highest synch speed available.  This is much too fast to record any detail in a dark scene.

A scene like this is very difficult to light and achieve a natural look. Typically, the scene would be dark and the warm glow from the candles would be lighting the subjects face.  Pop-up flash distorts the natural feel of the scene and produces an false interpretation of the scene.  Direct, on-camera flash gives off a harsh, directional light that produces distinct shadows, particularly when the camera is in a vertical position as it is here.  Furthermore, the color of the flash light seems false because it is balanced for daylight, while the scene itself usually has a warm, yellow glow associated with indoor lighting.  Finally, the flash completely overpowers the light from the candles falling on the subjects face.

In order to achieve a more natural look that harmonizes the background exposure with the foreground subject receiving light from the flash, it is necessary to decrease the shutter speed to a point where the background brightens up to normal exposure.  This may result in a very slow shutter speed, one that will normally blur a photo.  Since the flash is lighting the primary subject, it is not contributing any blur from the slow shutter.  Only those areas receiving no light from the flash are subject to blurring.  So slow synch flash is a technique where a shutter speed slow enough to record the background properly is combined with the on-camera flash lighting the main subject.  You want to try to harmonize the two lights.

Many modern cameras have a mode setting for accomplishing slow-synch flash automatically, but they do not always work properly because they are not tied into the nuances of the variety of scenes you may come across.   Furthermore, in these auto modes the camera selects both shutter speed and aperture.  You might want to use a different aperture for creative reasons,as we did in the sample below. 

To accomplish slow synch flash yourself, set the camera to "M" for manual mode.  Select an aperture setting that you find works best -- wide open to blur the background, or stopped down to bring the background more into focus. Take a light reading of the background scene, but select a shutter speed that will under-expose it approximately 1 1/2 stops.  Keep your flash in TTL mode so the camera will determine the correct amount of flash to deliver onto the foreground subject.  Take a test photo and examine it.  If you would like to have the background brighter, slow the shutter speed a bit more.  If you want it to be darker, increase the shutter speed.

Here is the same scene as above shown in slow synch.  The background is brightened considerably, plus it is softly out of focus because the slow synch lighting method allowed the use of a wide open lens aperture.  A natural, overall warm yellow glow permeates the scene and some light from the candles still falls on the subjects face.

 

Flash softening aides:

Direct light from the on-camera flash is very harsh and directional.  It produces a false impression of the actual scene with a hard edged shadow, normal color balance, and unflattering detail.  Slow synch already helps this, but using a diffusing element in front of the flash can help soften it more.  I researched several inexpensive, commercially available devices to discover which would work best at producing the most natural light.

Number 1 is the Gary Fong Puffer.  Number 2 is the Interfit small camera diffuser.  Number 3 is the LumiQuest Soft Screen.

No diffuser was used in the photo on the left.  The shadow is hard, and there is a distinct hot spot on the models forehead reflecting the light of the flash.  Number 1 shows the results of the Gary Fong Puffer.  Light on the models face is softened.  The glare on the forehead is diminished, and the shadow on the wall is softer and less pronounced.

Number 2 shows results from using the Interfit diffuser, and is the best of the three devices.  The models shadow has completely disappeared and the light on her face is soft and even with no hot spots.  Number 3, the LumiQuest is little better than using no diffuser at all.

Flash diffusion works best when the diffusing surface is large and placed far enough away from the flash to spread out the light.  When it is too close, it might be diffused but it is still directional and will cast a distinct shadow.  As distance and diffusion surface increase the light is more evenly distributed and falls on the subject softly and naturally.  In the samples above, one reflector, the Interfit small camera difuser, accomplishes this softening effect better than the others.

Conclusion:

In many situations an on-camera flash can supply the extra light needed to add detail to a dark scene or fill a harshly lit situation.  Using the light properly is the key to success on whether the resulting photos have a false  or natural look to them.   

Camera pop-up flash is not necessarily the best choice for lighting, but it certainly is the handiest and often the only choice available.  Learning to use it properly can greatly enhance capturing your candid moments.

In a future article I will expand the use of camera flash by showing the use of more powerful, auxiliary flash units that can be used either on or off the camera, and can be used in tandem with other flash units.

Technique: Capturing a Splash

The photo technique for capturing a high speed splash is not difficult once you understand the basic setup.  When taking pictures of water, or glass for that matter, you need to begin by lighting the subject from behind.  Since transparent liquids and glass allow you to see the background, this is the surface you need to light first.  If your subject is highly transparent, like water, the background may be all you need to light.  Otherwise you can add two more lights, one pointing directly at the subject from behind, and the other aimed at the subject from the front.

Blue gels were put over the lights to add some color to this scene.  The background lights were aimed low so there would be a fall off of light causing a gradual shadow towards the top.  Note the black lines in the water.  These are caused by reflections from the black tub placed beneath the water to catch it.  The lines help sharply outline the water shape against the light background

Equipment:

The key to freezing high speed action is having a light that gives off a very short duration of flash.  Most flash units made for SLR cameras fall into this category.  The flash duration is even shorter when the flash unit is used at a lower power rating, such as 1/16th or 1/8th power.  The trade off here is in depth of field.  In order to keep the splash in full focus you will need to stop the lens down to a low aperture, such as f/11 or f/16.  

A light meter that can measure light from a flash is helpful, but not absolutely necessary.  You can probably come close enough to the correct exposure with some trial and error tests.

This setup uses four Nikon SB-900 flash units.  Two are aimed at the background.  The other two are aimed at the subject, one from behind right, the other from the front left.  Two units are used on the background to keep the flash power on a low setting that will allow for even shorter duration of flash.  The black tub does double duty.  It catches the water from the splash, but also caused black reflections in the liquid and glass to help define its outline. 

 

Setting up the camera:

Your camera may have trouble focusing on the splash so set it to manual focus and, with the camera on a tripod, take a manual focus reading of an object placed in the spot where the splash will occur.  Put the camera in its manual exposure setting and choose the highest shutter speed you can for your camera/flash combination.  This is usually in the range of 1/250th of a second.  A lens of medium focal length is a good choice.  The ISO setting should be set low to maximize quality. 

An assistant dropped one ice cube into the soda from about a foot above the glass.  Timing has to be perfect to capture the splash at the right moment.  Try keeping both eyes open so you have a peripheral view of the hand dropping the ice cube and can be prepared to snap the shutter at the right moment.

 

The exposure on the background should be approximately 1-2 stops brighter than the light falling on the subject from the front.  With the camera set to the correct exposure for the subject, the background will now be pure white.

A shot like this requires pinpoint timing and very good hand-eye coordination.  An assistant threw a dart at the water balloon, and the shutter had to be pressed just as the dart entered the frame.  Keeping the shutter button half-pressed will shorten the length the finger has to travel to complete the exposure.

This is a combination of two water splashes similar to the one that began this article.  They were put together and twisted with post-processing software.  The exposure setting for all the images in this article were done at 1/250th second, ISO 200, and f/14.

How to Photograph Manhattanhenge

Twice a year, approximately  three weeks both before and after the summer solstice, the sunset lines up with the street grid of Manhattan.  The term for this, Manhattanhenge, was coined in 2002 by astrophysicist, Neil deGrasse Tyson of the American Museum of Natural History as a reference to Stonehenge in England.  It only applies to those streets beginning with 14th and going to upper Manhattan that were laid out in 1811.

The edges were allowed to go dark to enhance the effect of New York as a canyon of buildings framing the setting sun. See the photo at the end of this blog for a different interpretation of this same image.

Although the exact date for Manhattanhenge is when the sun is a full ball centered on the street as it sets on the horizon, it is possible to obtain great photos for at least five days before and after the main event.  

Be sure to allow plenty of time in advance of actual sunset.  You will have approximately ten minutes from when the sun peaks around the corner of the southern building until it finally sets.  So get to your shooting site at least a half hour before the time listed for actual sunset.

Photographing the sunset event is not too difficult, if you don't count taking your life in your hands to dodge street traffic.  The three things you will have to deal with are:  finding the right location, selecting the proper lens for what you want to capture, and setting the proper exposure when shooting directly into the sun.

Location:

While any cross street on the grid above 14th Street will provide the proper vista, a good choice is usually one of the wider streets, such as 14th, 23rd, 34th, 42nd, etc.  Two streets that make particularly good vistas are 34th and 42nd Street.  That is because they contain two important New York buildings that look distinctive in silhouette.  The Empire State Building is on 34th Street at Fifth Avenue.  The best place to record its silhouette and the sunset is from the East side of Park Avenue.    

A similarly dramatic view can be had of the Chrysler Building, which is located on 42nd Street at Lexington Avenue.  The best place to include it in your photograph is from an overhang that crosses 42nd Street near First Avenue.  Unfortunately, this is one of the most popular views and is very crowded with people, some of whom show up in the early afternoon to reserve a spot.  Another view of 42nd Street including the Chrysler Building is from street level where 42nd crosses Second Avenue.

The shooting spot happens to be right in the middle of the Street.  People wait for the "walk" signal and then quickly take a few photos before scurrying back to the safety of the sidewalk when the light changes to give the traffic the right of way.  Large groups also gather on the 42nd Street overhand that goes up Park Avenue to Grand Central Terminal.  The problem with this view is that the Chrysler Building is not in the shot so you have to be content with a simpler shot.

Whatever location you choose, it is best to scout it out ahead of time.  The Sunset event happens quickly in less than ten minutes.  When you couple that with all the traffic and crowds, you really do not have much time to prepare on the spot.  

Lens choice:

There are basically two types of shots to this event: One is a wide view that includes some of the story-telling detail of the city.  The other is a tight, telephoto shot of the ball of the sun, perhaps combined with some to the city traffic to add interest.

In this case a moderate wide angle focal length of 35mm includes a full view of the city with the Chrysler Building on the right framing the setting sun.

Here a long telephoto lens of 400mm compress the space.  This enhances the congestion of traffic and provides a solid circular shape to the sun.  The refracted blurs over the traffic were caused by shooting directly into such a powerful light.

 

For a vertical wide angle view you will need the equivalent of a 24-50mm lens.  (All focal lengths here are expressed for full-frame format cameras.  On a camera with an APS format divide the focal length numbers by 1.5.  For instance a 24-50mm in APS size would be approximately 16-33mm).  To obtain a horizontal shot like the first one on this blog entry you will need a lens between 16-28mm.

To capture the ball of the sun takes something between 200-600mm, with 300-400 providing a good combination of full sun and some compressed areas of the city traffic and buildings.

Exposure:

Shooting directly into the sun, especially with a telephoto lens will usually fool the camera light meter into under-exposing the image, resulting in a very dark silhouette with no detail.  It is best to put your camera on manual exposure mode and take a light reading.  Do not read the light with the camera pointed directly into the sun.  This will result in an under-exposed image.  Instead, point your camera to an area of the sky where the sun is just a tiny bit out of the frame, and take a light reading of this area.  Use that as the basis of your starting exposure.  To play it safe, bracket your exposure by shooting one full stop lighter and one darker than the correct exposure.

You probably do not need a tripod because you will be shooting directly into the sun.  This will provide an exposure with plenty of motion-stopping shutter speed.  An ISO setting of 200-400 should work fine for this, and should be sufficient to allow a fast enough shutter speed to hand-hold the camera at a lens opening of f/4-5.6.  

Special effects:

The exact same six-sided star filter was used to create these two photos.  The lens on the left was set to 24mm, while the one on the right was set to 44mmm.  This resulted in a much more exaggerated star effect.

 

A star filter can enhance the effect of the sun with a wide angle lens.  On a lens of normal to telephoto length it can become a bit over-powering.  

Conclusion:

In a situation like Manhattanhenge where you include a very bright light object and dark areas of shadow, it is best to take the photograph in RAW format.  This will give you a wider color and exposure latitude to make corrections and adjustments afterward.  All of the photos used above were done in RAW and enhanced later in Photoshop to bring out the color and details where desired.  

This is the same photo as the one at top that opened this blog entry, but it shows far more detail in the shadow areas and a different tint to the sunset.  Bringing out an image like this was only possible because it was shot in RAW, providing plenty of color and detail with which to work in Photoshop.

Filters: Using a polarizer

The ability to alter images in post-processing of digital photography has eliminated the need for most of the enhancement filters that had been so popular in film photography.  In fact, the digital sensor is so much more sensitive to optical quality that placing any filter -- especially one of poor optical quality -- in the optical path will most likely be detrimental to the quality of the final image.  One filter effect that does not lend itself to complete obsolescence in the digital age is the polarizer -- although one of the more common uses of the polarizer, darkening blue skies, can usually be done with simple post-processing.

A popular use of a polarizing filter is to darken a blue sky.  With modern digital photography and post-processing this is not as important a use as it once was.  In the photo above a polarizer was not necessary.  The sky was simply darkened and contrast added afterwards in Photoshop.

What to look for:

Polarizing filters come in two varieties: linear and circular.  On a camera incorporating either AF (auto-focus) or built-in metering -- which is to say all modern DSLR cameras -- use a circular polarizer.  A linear polarizer will disrupt the AF ability of the camera and give false readings to the built-in light meter. 

A polarizing filter must turn to produce its result.  This necessitates a filter mount that may be thicker than an ordinary filter, and can cause vignetting with wide angle lenses.  Better quality polarizing filters are specially made with thinner mounts.  As with any filter used in digital photography, it is best to spend a little extra for a higher grade filter mount, optical glass, and coating of the glass.  This will have the least negative impact on the optical system of the camera.

Darkening blue skies:

A polarizing filter can be used to add punch to a landscape or travel shot by intensifying a blue sky, particularly if there are interesting cloud formations present.  The clouds will stand out more dramatically against the deeper blue.

The photo of the Empire State Building on the left is without a polarizer; that on the right is with.  Notice how the sky is darkened, plus additional color and contrast are added to the building in the polarized image.

 As already mentioned, much of this darkening can also be done in post-processing of the image.  Nonetheless, when you combine the ability of the filter to also add deeper color to other reflective surfaces in your shot, using the polarizer may be a better solution that post-processing.  Keep in mind that a polarizer will only work on a blue sky.  It does nothing for a cloudy sky. The ability of a polarizing filter to darken a sky depends on the type of sky and your shooting angle in relation to the sun.

 

A polarizing filter has its greatest darkening impact on a sky when the section of the sky being photographed is at a 90 degree to the sun, as in the illustration above.  At sunset, with the sun directly behind you at 180 degrees a polarizer will have no effect whatsoever

The polarizer works best when it is used closest to a right angle (90 degrees) from the sun.  With the sun behind you or overhead, turn the polarizer in its mount until you see the darkening effect in the camera viewfinder.  A polarizer can darken the exposure by as much as 2-stops.  Be aware of this and make any necessary exposure adjustments in your cameras, if you are in manual exposure mode.  Your camera meter should be able to compensate for this adjustment automatically.  

This image illustrates two potential problems with adding a polarizer to a wide angle lens.  First, the filter mount was too thick for the 28mm wide angle lens on this full-frame camera.  This resulted in dark, vignetted corners in the image.  Second, the sky varies in darkness from left to right resulting in uneven exposure.    This is amplified more through use of the polarizer.  Here is an instance where no polarizer would have been better.

Using the polarizer in conjunction with a wide angle lens may cause other problems.  The blue sky changes intensity as it moves from the 90 degree angle in relation to the sun.  A polarizer can negatively emphasize this exposure contrast when using very wide angle lenses.  

A second thing to look for with a polarizer on a wide angle lens is vignetting, which is the darkening corners in the image.  This is caused by the lens actually seeing part of the filter mount and recording it as a dark out-of-focus area.  Be aware of these problems.  You may not actually be able to see them occurring through the viewfinder.  When using an extreme wide angle lens, it is best to also take a backup shot without the filter in place.

Restoring color to foliage and other reflective surfaces:

One of the most useful implementations of a polarizing filter is in landscape photography for bringing out the saturated color of foliage.  A polarizer also cuts down the exposure, sometimes by as much as one or two stops.  This can be an aid to photographing moving water where you want to create a blur of the water by using a slow shutter speed.

Without a polarizer to cut the reflections the leaves in the top photo are completely washed out through over-exposure.  In the bottom image the full color and saturation of the leaves is restored by turning the filter to eliminate the unwanted reflections.

A typical example of where a polarizing filter is important.  It was used in conjunction with a neutral density filter to lower the exposure to 1/2 second which added a blur motion to the moving water.  At the same time the polarizer cut out the reflections on the foreground leaves and rock surfaces to result in a deeply saturated photo with plenty of color and detail.

One of the most important reasons to use a polarizer is so you can restore color to reflective surfaces.  This is particularly prevalent when photographing landscapes with foliage.  The surface of leaves are pointed skyward.  Since the leaf surface is glossy, it will reflect the pure light falling on it from the sky.  This will result in loss of color and actual over-exposure of the bright, reflective surface on the leaf.  A polarizer can eliminate this reflection and restore the natural color beneath it.  

This is a dramatic example of how a polarizing filter can eliminate the sky reflections in foliage and bring out the true colors of the leaves and flowers.

Here the polarizer is doing double duty by darkening the blue sky and also bringing out the colors in the autumn leaves.

Eliminating unwanted reflections:

The ability to remove unwanted reflections can be beneficial when photographing any reflective surface, such as glass, metal, water surfaces, or even shiny skin. 

The polarizer works best at a 90 degree angle to what is being reflected.  The photo on the left of a store window reflects the street scene to such a degree that the sign in the window is almost illegible.  On the right the polarizer almost completely eliminates the distracting reflection and now the sign behind the window is clear

Use of the polarizer on the right image eliminated the white sky reflections in the statue and brought out more color in the metal.

The only difference between these two images is that the polarizer was used for the photo on the right.  Color saturation is restored, glare is eliminated.

 The polarizing effect can sometimes be overdone.  It is not always necessary to turn the polarizer to its full effectiveness.  This may eliminate reflections that are integral to the final photo.

In this instance, the polarizing filter totally eliminated the reflection of the sailboat in the water.  Including some degree of the reflection would have made the shot more interesting.

Here the polarizing filter was only partially turned -- just enough to deepen the colors in the water and the shiny skin of the model, but not so much that it eliminated the important reflection of the girl in the sand.

As always, proper use of an aid to photography should enhance the creative outcome of the image, not detract from it.  Know the limitations and abilities of your equipment and accessories.  Sometimes knowing when not to use a piece of equipment is as important as knowing when to use it.

All content copyright 2011, Tom Grill Images, LLC