THE MYSTERY OF FLASH REVEALED by Charlie Borland All text and images Copyright © Charlie Borland

LESSON 1 UNDERSTANDING FLASH In a perfect world for photography, every photograph we take would have perfect light, the perfect subject, perfect exposure, resulting in the perfect photograph. However, as you know there is nothing perfect in our world including the conditions, in which we photograph. Fortunately, there are tools available that allow us to capture pictures that may appear close to perfect and flash is one of them.

Flash has so many useful applications in photography. It can be the dominant light source or a secondary light source. Here it is secondary as the flash is set for flash fill to lower the contrast created by the sun. We will cover flash fill coming up.

In this course, we will closely examine how flash works in conjunction with your camera and explore techniques that will improve your photographs, and even open up creative options you may not have been aware. Once you understand the principals behind flash, you will find that using one is really quite simple. You can then take these fundamentals, and apply them to your particular flash and camera system.

There are many makes and models available today and they change literally on a daily basis. We cannot possibly cover how each and every flash unit works, but with the basic understanding of flash theory and technique, you should easily be able to revisit your owner’s manual and gain a thorough understanding of how your flash and camera system work together. Most of today’s state-of-the-art flashes have similar functions and we will examine many of them in this lesson.

Understanding Light Light is all around us! It comes from other locations, not from us, and it defines the world by creating highlight, shadow, and shape. When photographing, we are often presented with light that is too bright, too dark, too soft, or too harsh. In some cases, these light sources are adjustable, such as turning a light on and off, but in many others, we have no control. We cannot control the sun or a street light and so the photographer must find a way to make the light work in their photographs. These light sources are called Ambient Light, also known as available light. The sun is ambient light; the street light is ambient light; the light in the grocery store, office, or living room is ambient light. Strobe or flash light is supplementary light and unlike some ambient, is completely controllable from the camera. Your ability to use ambient and supplementary light together will often make or break a great photo.

Flash Metering One of the most important aspects in understanding flash is its metering ability. Today’s flash units are very sophisticated electronic devices. They have the ability to read the scene with the camera and output the necessary amount of light to properly expose the picture. These camera meters the ambient light and flash output to determine correct flash output by using a pre-flash. The purpose of the pre-flash is to send a weak initial flash to determine the distance from the unit to the subject. From this test, the camera can determine the best exposure and flash output for the subject.

Today’s flash units use E-TTL, which stands for ‘Evaluative through the lens’. Canon refers to it as ETTL, while Nikon uses iTTL (intelligent TTL) or just TTL. The pre-flash only fires when you have depressed the shutter enough to take to start taking the actual picture. Most importantly, it only measures flash output, and does not fire when the camera is also metering the ambient light. The pre- flash usually evaluates the exposure through the lens just like the camera meters ambient light. This system makes it harder to fool the measurement of light.

E-TTL/iTTL also has the ability to make subtle changes in output for flash fill techniques. To add even more ability to flash evolution, Canon added a great feature called AIM (Advanced Integrated Multi Point Control System,) which allows the camera to favor flash exposure where the focus point is set for more accurate exposure with off-center subjects. This type of technology is also seen in the Nikon equipment through their camera. By adjusting from matrix, center weighted or spot metering and auto-focusing. (Please read your manual for specifics). What this means is that whichever auto focus point you have set in the cameras viewfinder in where the flash will determine its proper flash output.

Today we have a newer version of Through the Lens technology. This new system is based largely on mathematical algorithms and measures the light before the pre-flash and after it. This allows it to evaluate all the light reflectance values with and without flash and provides a superior evaluation and more accurate flash exposure. Types of Flash Today, many cameras come with flash units built in, but not all. These built in pop-up flashes are convenient and easy to use, but are also low in power and only work well for subjects that are close to the camera. These flash units are for recording subjects in conditions in which ambient light is not sufficient. They produce a harsh, flat, and contrasty light.

External flashes have more power and capabilities. They can be removed from the camera for other lighting options. Most of today’s film cameras support these different types of technologies, while many digital will only support the newer versions. For Canon digital users this means only EX flash units. Nikon users will be successful with flashes such as the SB900, SB800, SB600, or DX flashes. It is very important that you do your homework and make sure that your system is integrated in a manner you wish.

On the right is an older Vivitar 285. This is an old workhorse and is not TTL compatible with your camera. It does have the ability to measure flash output but is not TTL nor nearly as accurate as your state-of-the-art flash. This flash is a great addition to my flash arsenal as a off-camera unit that I might place somewhere in my scene and fire it remotely.

This photo of my son was taken in a local cornfield. I purposely dressed him to look like a kid who lives on a farm. I also used flash with a warming filter to make it look like sunset lighting. We will cover filters in Lesson 4.

Understanding Flash Theory The flash unit is a complex system of electronics containing a capacitor that is charged full of energy and then discharges in an instant when you press the shutter. It provides a burst of energy into a tube full of gases. The speed in which a flash discharges light is measured in milliseconds. This brings us to our first important concept that must be understood. There is a distinct relationship between f/stops and shutter speeds, and how they affect flash exposures. To understand this fully, disregard for the moment the settings on your camera and shooting modes such as Program, Aperture Priority, and Shutter Priority and also forget about TTL for the moment.

Consider the following information with the camera set on manual exposure and the flash output is set manually at full power.

The rule is:

- Shutter Speed controls the amount of time that light is allowed to expose the picture.

- Aperture controls the amount of light allowed to expose the picture.

What is important is how you apply this concept. Because a flash’s output duration is instant (milliseconds), the shutter speed does not control the flashes exposure. Think about that! If your shutter speed is 1/60th of a second and the flash is one millisecond, then does it matter where within the 1/60th that the flash fires? No it doesn’t. If you are at 1 second or 1/125th, the flashes output duration is relatively the same, an instant burst of light. Here is what I call a “timeline” of three different shutter speeds and the relationship with the flashes duration. The following diagram is meant to illustrate this point: no matter whether the shutter speed is at 1/30th or 1/125th, it cannot control the flash exposure.

------1/30th second ------1/60th second ------1/125 second

Here you can see that 1/30th second is twice as long as 1/60th, which is twice as long as 1/125th. The flash spikes when the shutter is opened na its length of time remains the same no matter the shutter speed. At 1/30 the shutter remains open long after the flash burst while 1/125 is open a much shorter time after that burst. This example is only meant to illustrate a point and is not proportional.

Important Point: What this means is the shutter speed is ONLY for changing the exposure of the ambient or background light. It does not change the flash exposure. Here are two examples: the image on the left is your typical indoor flash picture and had a shutter speed of 1/60th (P Mode). On the right is the same picture at ¼ second (A Mode). On the right, you see more ambient light in the room and even the window light is putting highlights on her cheeks. Flash exposure remains the same in both examples if you look at the face, just the ambient room light has changed. In addition, the image on the left is P mode, which has a limit on shutter speed of 1/60th meaning it cannot pick a longer s.s. that 1/60, which in this case provides a dark background. Image on the right is in A mode and selects the shutter speed for proper ambient room exposure no matter how long (up to 30 seconds).

F/stop or aperture on the other hand DOES controls the amount of light allowed to expose the picture. This means that by changing your f/stop, you control the brightness of your flash exposure, just like an ambient outdoor exposure! Here is an example: take a picture with the flash set on manual (not ETTL) and at full power let’s say that f/stop is f/11. The picture is too dark, so you open up your f/stop to f/8 to let in more light, hopefully creating the correct flash exposure. On the other hand, if the picture at f/11 is too light, you close the f/stop down to f/16 to let in less light from the flash. These concepts are vital: shutter speed does NOT control flash exposure while f/stop DOES. More Theory: Consider the above chart of fstop aperture sizes. If you start with an f/stop of f8 and change it to f11, you have reduced the size of your aperture in half, meaning you also cut the amount of light moving through the lens in half as well. Now if you were using the flash for a correct exposure at f8, and then changed to f11, the picture will be dark because you made aperture half the size of the previous aperture so half the light is coming in to expose the picture. If you go the other way, to f5.6, you have doubled the amount of light coming through the lens and the picture will be overexposed. This proves the aperture or fstop controls flash exposure while shutter speed does not.

The Reality Now before moving on I should clarify the previous paragraphs as correct flash theory, because it is theory and it’s based on manual flash. The reality is when you are in TTL; the flash will adjust automatically to any changes in fstop you have made. So if you move the fstop from f8 to f11, the flash will automatically double flash output for a correct exposure. If you adjust from f8 to f5.6, the flash will reduce by half the amount of output for a proper exposure. It’s this function that makes flash so easy to use: ETTL does all the work. You will choose to use manual modes in the camera and on the flash when you fully understand how it works and wish to use it more creatively.

Here is an exercise for you to try: Go into a room you can make dark. With flash on camera, set the camera to Manual shooting mode and set your shutter speed to 1/60th, the f/stop of f/8 and the flash on E-TTL. Focus on an object in the room and then turn off auto focus on your lens so that once you turn off lights the camera is not looking for something to focus on. Now turn off the lights, and take the picture. Next adjust your shutter speed to ½ second while all other settings remain the same.The room is still dark so take a second picture. Comparing the two photos, there should be no difference between the two as long as the room was dark. The point is that changing the shutter speed did not change the flash exposure. If the room was not totally dark you might see some ambient light in the photo, but flash exposure should be the same.

This picture is not relevant to the current topic, but was a fun use of flash. My wife and I decided to have some fun with an upcoming birthday party we were having. I used a 20mm lens and had my wife hold the birthday cake out towards the camera and me. I bounced my flash off the ceiling and took picture 1. She set the cake down and then held out her hands as if holding a giant cake and I took picture 2. I then went into PS and cut the cake out of picture 1, enlarged it until it fit her outstretched hands in Image 2. We will cover bounce flash in the next lesson.

Sync Speed Synchronization speed is the fastest shutter speed you can use with your camera and a flash. This is an important fact when using SLR cameras with focal plane shutters. I believe every film 35mm SLR uses a focal plane shutter and the sync speed varies depending on make and model. I have owned cameras with sync speeds from 1/60th second, to 1/90th, 1/125th, 1/200th, and even 1/250th. Now some are 1/320. (PLEASE READ YOUR CAMERA MANUAL TO DETERMINE YOUR CAMERA’S SYNC SPEED.)

This is a different concept than mentioned previously where the point was made that the shutter speed had no effect on flash exposure. Here, we are talking timing and the synchronization of the shutter and flash occurring together. If you use a sync speed faster than the designated you get a picture that is part picture and part black. The reason for this is that the flash sync speed is the fastest speed where the first shutter of the camera finishes opening before the second shutter starts closing.

This is what the wrong sync speed can look like. The flash fired when the shutter was not completely open. The flash output builds, fires, and falls off quickly.If your shutter is just about to open or close, the entire picture will not be evenly lit. The result is often a dark border.

Film cameras are equipped with curtains in the shutter that move vertically, exposing the picture as they move. When using fast shutter speeds, these curtains literally become narrow slits exposing as they go. If the flash fires when the narrow slit is at the top or bottom, this results in an incomplete flash exposure. The top sync speed for each camera varies, but at the designated shutter speed the curtain is open completely when the flash fires exposing the entire image.

Many new cameras won’t let you take a photo, if the sync shutter speed is incorrect and flash on. They give a warning indication and won’t let you take a picture. Check your manual.

Things are changing in this fast-paced digital revolution. The word is that it wont be long before some digital cameras have sync speeds up to 1/500th second. They use an electronic shutter system and as previously mentioned many new cameras won’t let you take the picture at the wrong sync speed. It is important that you understand your cameras sync speed capabilities.

So to use your flash to its maximum capability and get the most power from it you want to use it at a shutter speed no higher than its designated sync speed. That allows you to use all the power the flash can provide for perfect exposures. However, there is a feature that allows you to use a shutter speed higher than the designated sync speed and it is called High Speed Sync and its advantages are covered in a later lesson. But I need to mention this now: if you are a Nikon user with newer gear, you have an option in your menu that is called Auto FP with FP meaning Focal Plane.

It should be called, Auto High Speed because that is what it is about. If you turn this on you can shoot flash at any speed, anytime, and go your merry way never thinking about anything ever again. (Gee that sounds good!) There is a problem with this however and this is in a later lesson. When you use High Speed sync to get faster shutter speeds, then the shutter is open for a shorter time. When this happens, the flash must cut output so that it can output the flash burst within the time the shutter is open. Less output means less distance, less distance means closer subjects and so on. You can use a flash to stop the skier in mid air and in FP you can use 1/8000 of as second. Use the flash to fill in shadows and that skier can be no further than 3’ from the camera. Now it is useless. I bring this up now, and will cover more later so that you know what is happening when you shoot your assignments. If Auto FP is on and you shoot assignments and discover later that your sync speed was 1/400 and Charlie said there should be a black border and there aint, it is probably because Auto FP was engaged. Nikon users: check you settings!

I photographed a friend with his dog and used the very simple flash fill technique with an on-camera flash. Fill flash is coming up!

Shooting modes Cameras meter flash and ambient light independently of each other. Your camera probably comes with several different shooting modes. On Canons: P for Program, Av for Aperture Priority, Tv for Shutter Speed Priority and M for Manual. On Nikons: S is for Shutter Priority, A for Aperture Priority, P for Program, and M for Manual. From here on I will just refer to these modes as AP=Aperture Priority, SP=Shutter Priority, M = Manual, P = Program mode. P mode is designed for you to photograph without much consideration to the quality of your picture. Program mode picks shutter speeds between 1/250th for very bright scenes and 1/60th for very dark scenes. The limit in shutter speed range is designed to allow you to not use a tripod, no matter the lighting conditions. This mode works automatically in several ways. If the ambient light is bright, then it chooses to use flash as a fill light to fill in the shadows. If the ambient is dark, then the flash acts like a key or main light. The problem is when the background is darker (meaning it needs a longer shutter speed than the 1/60th limit) then the photo will have the black background look from underexposure even though the flash properly illuminates the subject. This works fine for many applications like shooting the office Christmas party, but your creative use is very limited.

These pictures show the difference between P shooting mode on the left and Av on the right. P chose a shutter speed of 1/60th while Av selected a speed of 1/30th. (Nikon users do have a menu option to change the longest shutter speed in the menu. I do not know why be they do.)

Here are two examples to further illustrate this concept. The sun has set so it is dark outside. The image on the left is P mode and the camera chose a shutter of 1/60th, the longest s.s it can use in P mode. The image on the right is Aperture Priority mode and the camera chose a shutter speed of ½ second for proper ambient exposure. Notice the blurring on the right image? ½ second is too long to handhold the camera so a tripod would have helped here. (Also when working with ones children as models, it helps to offer money, otherwise you get facial expressions such as the left image. A little cash brightens their mood as illustrated in image 2. LOL)

AP mode, which stands for Aperture Priority allows you to select the f/stop you wish to use, while the camera selects the appropriate shutter speed based on its metering of the ambient light. The f/stop you choose could be based on the amount of depth of field you wish to have in your subject. The shutter speed chosen by the camera is designed to accommodate the aperture you have chosen. It could range from 30 seconds to the faster flash sync speed. This is an important consideration, since too slow of a shutter speed could require a tripod to avoid movement and blur. If you have set the exposure combination you wish to use, and the shutter speed indicator (30 seconds) blinks inside the viewfinder, it means that the shutter speed required for your chosen f/stop is longer than 30 seconds. Here you will need to readjust your f/stop to achieve a shutter speed of less than 30 seconds or use a cable release and set your shutter speed to BULB which means as long as ther shutter or cable release is depressed, the shutter is open.

The newer Nikons operate differently (check your manual. Traditionally, when cameras are in Program mode, they use a shutter speed between 1/60th to 1/200th or 1/250th and when in Aperture Priority mode, the camera selects a shutter speed that allows a properly exposed background with speeds on some models up to 30 seconds. However, the newer Nikons are limited to shutter speeds between 1/60 - 1/200th just like Program mode. I am not sure what Nikon was thinking, but they did it this way.

To override this, you need to select the SLOW SYNC MODE, and then the camera will select a shutter speed for a properly exposed background. To set the SB800 to SLOW SYNC MODE, go to the mode dial on top of the camera and select the flash ‘lightning bolt’. Using the Main Command Dial, rotate it until you have selected the slow sync mode icon. In addition, the Nikon D70 does not have a slow sync feature, and requires that camera use the rear curtain sync instead. Even though you will not get the exact same results, they will be similar.

Another thing to consider when using A/Av mode is the aperture you choose determines the shutter speed and if light levels are to low, your shutter speed may be to long for sharp pictures as illustrated in the two pictures above. You would then choose an fstop that allows a faster shutter speed for hand holding.

SP mode is used when you wish to control the shutter speed and are less concerned about the aperture or depth of field. Tv/S mode chooses the correct aperture based on metering the background correctly. When using this mode, the flash is usually acting like fill flash. The cameras goal in Tv/S mode is to expose properly for the background and flash is secondary. If you are using this mode and the selected aperture at its widest setting begins to blink, this indicates that your shutter speed is too fast, and that the background will be underexposed. The solution is to adjust the camera to a slower shutter speed until the blinking stops. While working in Aperture Priority or Shutter Priority modes, the flash acts like a fill light, while the camera chooses the correct ambient exposure. Remember, you cannot choose a shutter speed faster than the cameras designated sync speed when using flash.

In Manual Mode, I shot the photo on the left at the meters recommendation 1/60th @ f/8. Then, I shot another image (right) where I purposely underexposed the ambient light by setting the shutter speed at -1 1/3 from the left image for and exposure of 1/160 @ f/8.

M is for manual. In many ways, this is most useful and versatile of the camera’s shooting modes for using flash. You choose the aperture AND shutter speed, based on what the cameras metering suggests. The flash, as in all modes, will choose the correct output to illuminate your subject based on the chosen fstop. However, it should be noted that at this point, I am only referring to the CAMERA mode for manual, NOT the flash’s mode for manual. What does that mean? With Manual set on the camera, you have the ability to adjust your exposure combination any way you wish, and the flash in E-TTL/iTTL will adjust the flash output to match your chosen camera settings. The flash also has the ability to be set in its own Manual mode for other flash uses and this will be covered later. EC, aka Exposure Compensation Exposure Compensation is used to increase or decrease your exposure beyond what the camera recommends and it has nothing to do with flash exposure. If you have heard the term “bracket your exposure” they are referring to compensating the exposure. Anytime you are out photographing and bracket your exposures by shooting at the cameras recommended Normal exposure, then underexpose by choosing a faster shutter speed, and then overexpose by choosing a longer shutter speed, you are using EC. There is no EC button or anything called EC, it is simply a function of changing the exposure from what the camera suggests by purposely underexposing or overexposing. This is very useful and you will probably find yourself using this quite often in conjunction with flash photography.

When the camera recommends an exposure setting based on its ability to interpret the scene, you set the exposure it recommends when in manual mode by turning the appropriate dials until they indicate a proper exposure. In Av mode, it selects the shutter speed based again, on its interpretation of the tones within the scene. There will be times when you wish to override these recommendations and this is where EC comes into play.

An example; you are using Manual shooting mode on your camera and the meter suggests 1/125 @ f11. You take a picture and find it a little dark, so you change either your shutter speed or aperture to increase the exposure. As illustrated by this photo, you would use the appropriate dials on your camera.

For the Canon, the Main dial adjusts shutter speed while the Quick dial adjusts fstop (in Manual shooting mode). However, in Av mode, the Main dial on top adjusts the exposure combinations. When turned it adjusts the exposure by moving the fstop one direction and when it does, the shutter speed adjusts accordingly to compensate for the change in fstop. f/8 @ 1/125th is the same exposure as f/11 @ 1/60th, just a different combination. But, if you want to use EC for a minus adjustment to the shutter speed, you would turn the quick dial to adjust the desired amount. For Nikons, the Sub Command Dial on top/front adjusts the aperture while the Main dial on the top/back adjusts the shutter speed. In Aperture Priority mode you spin the Sub Command Dial to adjust the aperture and the camera automatically follows by adjusting the shutter speed for a proper exposure combination.

So how does it all work? Example 1: Shooting mode is Manual, flash on ETTL. Image below left is f8 @ 1/8th and is what the camera suggests. Now I am using EC, which in this case is the shutter speed I plan to move. The middle image is f8 @ 1/15th, which is EC -1 and underexposing the background -1 stop. The image on the right is using EC -2, which is f8 @ 1/30th and is underexposing the background -2 stops. Since the fstop didn’t change, the flash output an accurate amount of light each time for proper exposure. Remember; shutter speed controls the background exposure.

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Example 2: Shooting mode is A/Av and flash on ETTL. The aperture is set to whatever f/stop you have chosen. As you spin the main dial switching f/stops, the camera automatically adjusts the shutter speed to accommodate the changes you are making. Now let’s say you want to make the background darker or lighter and still be in A/Av mode. In these three photos you can see on the exposure bar the normal exposure, the -1 EC, and the +1 EC. On the Canon you adjust this with the main dial on the back. On the Nikons, you adjust the exposure compensation by holding down the +/- button and rotating the Main Command Dial for an +/- EC.

Exercise: Go outside on a cloudy day or wait for the sun to be setting, whichever provides you a lower ambient light level. Point the camera at an object or person. Shooting mode on camera is set at Manual and Flash is set at ETTL. With flash turned off, adjust the cameras meter for what it says is a proper exposure of the ambient light. Let’s say for the demo that it suggests f8 @ 1/15th. Turn the flash on and take a picture. Now set the shutter speed to 1/30th, take a picture and set it again to 1/60th, taking a third picture. What you should have is three photos in which the flash on the person is the same, while the background got darker in the second image and even darker in the third.

Note: the first picture will have a brighter looking face than the third picture because the ambient light contributed to the exposure where in images 2 and 3 the ambient got darker and contributed less.

Flash is very valuable when shooting all sorts of outdoor action and adventures. For rafting, I like to use a slow shutter speed and full flash to freeze the subject and have the action blur behind them. Here the aperture was f/5.6 and the flash outputted the correct amount of light for proper flash exposure while the camera chose (A/Av mode) a shutter speed of ¼ second. This technique is explained fully in lesson 4.

Auto Flash Heads Today’s flashes have a motorized zoom that uses a fresnel lens to focus the light from the flash. With a telephoto lens, the flash zooms in, and when you are using a wide angle, the flash zooms out. This increases the range of the flash by only covering the area in the photograph that you are zoomed on. This ability allows the flash to concentrate light only in the areas of the frame, and increases the flashes range. If your flash is designed for your camera, the two will work together. As you zoom in on your subject, the flash head moves as well. Depending on your camera system, this ability may become disabled when you move the flash head into bounce mode so check your manaul.

To make sure your Auto Flash Head is on or to disable it, follow these steps: On the 580EX, push the ZOOM button on the rear of the flash until the M is there (if you want to disable Auto Flash Head) or until the M is gone (if you want Auto Flash Head to be on). If you are choosing manual Flash Head, you do as above and when the M appears you spin the Select Dial until you reach the desired focal length lens you wish to use, as indicated on the LCD, then press SEL button.

On the SB800, to manually set to a wider lens, press the ǺǺǺ (three little trees), as you press it, the focal length lens you desire will be displayed. Stop when you reach the length you want. To go to a telephoto, push the opposite side Ǻ (one little tree) until you reach the desired focal length.

Why would you choose to use Manual Flash Head adjustment? You might be using cameras that are not compatible with the flash itself such as non-EOS camera for Canon, or non-CLS Nikon cameras. Check your manuals for specifics. Also, if your camera is using a wide angle lens but you want the light output to be focused on a certain area within a scene, you would use the manual flash head ability. Let’s say a wide angle of a flower garden, but there is a bird nest in the small tree and you want some fill flash just hit the bird nest. This is an example where you would disengage the auto features and manually set the flash head to be telephoto and flash a specific area of the birds nest but not the flowers.

Many flashes come with wide-angle diffusers, which allow the flash to cover even wider-angle areas such as 14mm. On the 550EX the wide angle diffuser allows for lenses to 17mm, the 580EX to 14mm, and the SB800 to 14mm.

Here is the flash diffuser for using with a 17 mm lens on the 550EX, extended and in place.

In addition the SB800 and 580EX have built in bounce cards to create catchlight’s in the subjects eyes. This is only useful when bouncing flash because the head needs to be pointed up so the bounce card catches some of the flash output and bounces it to the subject. Here is the catch-light panel on the 580EX. Keep in mind that these are pretty worthless for bouncing much light on the subject in comparison to more commercial brands like the Gary Fong and Honl.

Recycle time The frequency in which a flash can recycle for another output of flash light is an important consideration to understanding your flash unit. Each will vary, so check your owner’s manual. Once the unit discharges a flash output, it takes a certain amount of time to recycle and be ready again for another flash exposure. This varies depending on the f/stop you choose to use also.

For demonstrations purpose, I will use my Canon 550EX Speedlight as an example. In Normal Mode, the flash will be fully recycled anywhere from 1/10th of a second to 8 seconds with fresh batteries. My newer 580EXII states .1 – 6 seconds so it is faster. The difference is based on the flash output; if your exposure requires the flash to discharge the entire capacitor to light a subject far away, the recycle time will be closer to 8 seconds. If you are using flash fill to light a flower 2’ from the camera, the flash will discharge substantially less to light the flower and the recycle time will be shorter.

For these two photos, I left my motor drive on 5 frames per second and shot these two images back to back. The flash was unable to recycle fast enough for image on the right. You need to take your flash’s recycling time into consideration when adjusting your camera’s settings. Bottom line is that you want to choose an f/stop that meets the needs of the subject and no more. Does everything need to be shot at f/16 for depth of field? I doubt it and if you shoot everything at f/16 then the flash is outputting all its power meaning it takes longer to recycle and eats batteries faster.

If you are photographing a moving subject, and want photos as it passes by, you need to have your flash and camera exposure combination set to allow rapid recycle time so this means as fast a shutter speed as the camera is capable and an accompanying aperture that is as wide as possible. This means flash output is short allowing for a faster recycle time. Also consider a supplementary battery pack as these allow faster recycle times as well.

Here is a hypothetical example: Your exposure is 1/60th @ f/11 and when you fire the flash/camera to take your picture, it takes 6 seconds to recycle. 6 seconds is too long to wait for the flash to recycle because your subject has already gone by after the first flash. Now if you set your shutter to its highest sync speed of 1/250th of a second you can open up your f/stop to f/5.6 where the recycle time is now at 2 seconds. (Again, this explanation is not factual and meant for demonstration purposes only.) You may also be able to use High Speed Sync which is discussed in a later lesson.

Guide numbers Guide numbers are the industries rating for how powerful your flash is and uses mathematical calculations to determine it. GN’s are not important after this description so if this is confusing it wont matter because you will be using flash in other ways and will have no need to think about GN again. (If it is not in the lessons somewhere I will be asked about it.)

The only thing you need to remember is the higher the GN, the more powerful the flash unit. Do not get hung up on this no matter what the salesman said, it is not important. Here is the explanation anyway:

You can use the GN to determine your fstop by taking the GN and dividing it by 10' and that is your fstop. So lets say your GN is 160 and at 10' (where your subject is) you divide 160 by 10' = f16. Its very simple. If your subject is 12' then 160 divided by 12 = f13. You would set your flash to manual output, not ETTL, and use it at full flash output to use it this way.

I was shooting a series of lifestyle images for an insurance company and it was an overcast day. You can get some ugly shadows on overcast days like sunny days and flash fill will help reduce shadows in both cases. Angle of Incidence The Angle of Incidence of light is an important aspect about lighting and should be understood. When a light source emitting light reaches an object at a certain angle, that light is then bounced off the subject at the same angle. If the sun is at a point in the sky where it shines a specular highlight on a surface of water at a 45-degree angle, then the light bouncing off that water surface will be at a 45- degree angle as well. Imagine that you are taking a picture of your friend in front of a window. When you take the picture, your flash has just created a glaring hot spot in the window behind your friend. This is because the Angle of Incidence is equal and at the same angle from light source to the camera. If you moved to the left or right and move your friend accordingly, you can move the reflection caused by the Angle of Incidence out of your frame.

Here is an example of angle of incidence where the flash is reflecting in the window as in image on the left. By moving to the left and changing my angle, I have moved the reflection to the left and you can see the hot spot. By moving a little further left, I can completely eliminate the angle of incidence reflection from the glass. Just like looking at yourself in the mirror, straight on you see your self and this is zero angle of incidence. Look straight in and see what is bounced back……you. If you step to the side and can no longer see yourself, the angle is off. Flash works the same. If you are straight to the reflective surface, the flash bounce back will go right into the lens. Changing angles enough where the angle of incidence spot is out of your viewing frame and you have solved the problem.

Inverse Square Law The Inverse Square Law relates to the fall-off of light in relation to the distance from flash to subject. Think about this: you are at an indoor concert and you hold your camera up to photograph the musicians on stage. The camera and flash fire and when you view the picture what you see is the guy 3’ in front of the camera is ‘fried’ by the flash, the people 10’ out are perfect, and the musicians on stage are dark because the flash never reached them. The light had fallen off before reaching the stage. The Law states that when flash-to-subject distance is doubled, the light reaching the subject is cut to ¼ or reduced 75%. As indicated by this diagram, if the subject is 5’ from the camera and your exposure is f/16, when the subject is moved to 10’ or double the distance, the falloff of light reaching the subject is reduced to 25% of the light as received at 5’. The new f/stop would be f/8 or two stops more than at 5’.

The Inverse Square Law is a theory on how light works and falls off as the distances change. Again this is theory based on the flash outputting the same amount of light in both cases at 5’ and 10’. This does not take into consideration the ability of the flash to increase or decrease output to compensate for the distance changes. If you were in ETTL and your subject moved from 5’ to 10’, then the flash automatically increases flash output to compensate for the distance change.

However, one consideration with light falloff is making sure you chose settings that allow your flash to send enough light to the subject at a chosen distance. If you are photographing a group outdoors at night and at 10’ from the camera and the exposure is perfect, when they move to 20’ they might get very dark. Even though your flash is on E-TTL/iTTL, you might have reached maximum flash output and in combination with light fall-off, the second picture becomes dark. This means that at the fstop you chose, the subjects are beyond the flashes range and not enough light is reaching them. The first thing to do it choose a wider aperture and let’s say for this example, you switch from f16 to f8. You then have dramatically increased the distance that the flash is able to send light for a proper exposure. This photo was for an insurance company and you can see we had harsh, midday sun.I used a flash fill to reduce the shadows and contrast, but set the flash to be only -2/3 lower than the exposure settings recommended by the cameras meter. (i.e.: the camera suggested 1/125th @ f/11 and the flash output was set to be f/9.)

The Power of ETTL What makes flash photography so easy is the power of ETTL. This function of your flash and camera working together can in most cases, provide you perfectly ‘flashed’ pictures. You simply set the flash to ETTL and choose the shooting mode you want to use on the camera. No matter what shooting mode you choose, your flash will output the necessary amount of flash output for a correct flash exposure. No matter whether you choose P mode, AP, SP, or M modes, the flash is in automatic and sends out the correct flash to your subject because its job is to output light based on the chosen fstop. It does not care what shooting mode you are in because shooting modes only control background exposure. We will discuss the power of Manual flash in an upcoming lesson.

Summary:

Key points to remember:

1.) Aperture controls the amount of light allowed to expose the picture. 2.) Shutter speed controls the amount of time the picture is exposing, but not the actual flash exposure. 3.) You can control the flash exposure by moving the flash closer or farther from the subject. 4.) The camera has a maximum sync speed for use with flash 5.) Shooting Program mode weighs towards flash exposure more 6.) Aperture Priority and Shutter Priority modes weigh towards background exposures

Watch these Video Clips Understanding 550EX #1 Understanding 580EX #1 Understanding SB800 #1 Understanding Shooting Modes Simple Flash Photography SB 800 versus SB 900: what's new? In late 2008, Nikon introduced the SB 900. There are a lot of new features on the SB 900 that deal mostly with handling and the interface. The functions still pretty much operate the same as the SB800, but it's how you reach and use those features that have been significantly improved.

One of the first features that become pretty handy is the flashes ability to determine whether you're using FX or DX digital SLR's. What this means is that the camera body you have contains either a cropped sensor or a full frame sensor. The SB900 has the ability to detect which camera you have and make an adjustment for the flash coverage. For example, for an FX format camera the zoom range is 17 mm to 200 mm. If you have a DX format camera this range increases on the wide angle end from 12 mm to 200 mm and the ability to zoom to 200 mm is a first for Nikon flashes.

The next thing relates to the size of this flash and if you have one and have compared it to an SB800 you'll notice that it is substantially larger. I'm not sure that this is a bad thing with the exception of needing more room to store it in your camera bag and the additional weight. But what has come along with that size increase is a larger LCD for easier reading, and more space for the function buttons. In addition, Nikon has gone to a rotary dial for making adjustments rather than the ‘push that in dial’ of the SB800 and this allows you much quicker changes to the settings of the flash.

The flash head also for the first time has the ability to rotate a full 360°, 180° to the left or 180° to the right and this is a first. Another very cool feature is the fact that you can adjust the flash head coverage by using what they call head style. The settings are CW, which means a very narrow beam, STD which stands for slightly focused beam, and EVEN which means that the flash spread will be even from left to right in your viewfinder

This has huge advantages! Think for a moment of an image you are about to photograph and let's say for example you're photographing a rock star standing in the middle of a remote highway in the middle of the desert. (Sounds like the dream assignment.) You have on a 24 mm lens and the rock star is standing on the yellow stripe in the middle the highway so you are seeing the person in the middle your frame and somewhat small. You also see what's way over to the left in the frame and what's way over to the right in the frame. But, you only want the flash to really light the rock star and not what’s way left or right. With a normal flash on the camera used in a normal way the flash is trying to light the entire scene that you are seeing through the viewfinder. However if you set the SB 900 to CW to force all the power of your unit into almost a spotlight beam, this increases the range of the flash to hit subjects further away and that is very cool. Another fabulous feature is the SB 900 re-cycles at a minimum is 30% faster than the SB800. If you use the SD-9 supplemental battery pack the recycle times can be as fast as 1 second and if you are a wedding photographer for example, this would be a fabulous improvement.

The flash still has abilities that the SB800 including full wireless ability and they can be controlled in three separate groups. It also comes with a new ability to control overheating of the flash tube, the first ever seen in a flash unit. If you are shooting in high-speed flash situations where the flash's firing constantly and rapidly, there is the possibility of overheating the flash tube and basically frying the electronics. It's called the thermal protection feature and has temperature gauges in the unit that will automatically shut down the flash when it begins to overheat. This of course can save you about $500 because you won't have to buy new flash.

One subject of using flash that we will cover later in the lessons is using gels attached to your flash to change the color of your flash unit. We do this for cool effects sometimes but even more useful is to use color correction gels to change the color of the flash so that it matches the color of interior lighting inside a building or room. As you know lamps sitting on an end table in the living room are often tungsten balanced which means the color of light admitted by this lamp is very amber orange in color. Old fluorescent lighting fixtures in lots of office buildings tend to be green in color when photographing with daylight settings on your camera.

The cool feature about the SB900 is it has a collection of gels for use with the flash and a nice little gel holder. By setting your camera on auto white balance and attaching the appropriate gel to the flash, the camera knows what settings you are at and will balance the color of the scene quite accurately.

The drawbacks to this flash are that it's much bigger, it costs more, and much to my surprise, it's not as powerful as the SB800. There's not a huge difference with some estimates saying that the SB900 is about 15% weaker in output than the SB800. This reduced output can be offset by using the focusing aspects of the flash head. If you concentrate the beam to be more centered that will allow the light to go further and this increases the guide number.

All in all this is a great addition to the Nikon product line and shows continued improvement with innovation and functionality of these flash units.

Using the flash, step by step Now that we have covered all the details of flash and how it works, here is the step by step approach for simple flash photography. 1) The flash attaches to the hot shoe. 2) Turn on the power 3) Set the flash to ETTL/ITTL. It will output the correct amount of light for proper flash exposure. 4) Set your shooting mode to Program, Aperture Priority, Shutter Priority, or Manual. Use Program for indoor party photos, use Aperture Priority or Shutter Priority for outdoor photos where you want the background in the photo. (I rarely use Shutter Priority with flash because I get the results I want easier with Manual or Av) You can also use Manual, just make sure that you set the f/stop and shutter speed correctly based on the cameras meter suggestions. 5) Shoot some photographs.

Strategy using Flash If you are using flash on-camera and in TTL and your subject is far from the camera, like a group at a wedding, you should use a wider fstop like f8, f5.6, f4 or even wider. This is to make sure the flash has the ability to output enough light to distant subjects and allows for faster recycle time. On the other hand, if your subject is closer to the camera, like the bride and groom close-up, you can use smaller f/stops like f8, f11, f16. I usually do not use a smaller fstop than f11 and the reason is that at f11, I usually have all the depth of field I need and the flash is discharging a lot of light for a proper exposure. This then makes the recycle time longer and eats up batteries faster.

Choosing a shutter speed is important as well. When using automatic flash in TTL, the most popular shooting modes are Manual and Aperture Priority because they are so easy to shoot with and have the most flexibility. One thing to consider is using a shutter speed that allows for sharp pictures. We know that 1/60th is about the slowest shutter speed we can use and still maintain a sharp picture. If you are rock steady, you can get away with 1/30th, but any longer will result in pictures that start to blur, unless you are using VR lenses. If you have lenses with image stabilizers they will allow for longer speeds and you get sharper pictures with the longer speeds, but that is another subject for another time.

In Av mode and hand held, you should choose an aperture that allows for 1/60th second or faster (in bright light) to maintain sharp pictures and when hand holding the camera. If the light level is low, then you may need to set your fstop to very wide, like f4 or f2.8, to maintain that 1/60th shutter speed. However, if depth of field is also important you have to make some judgment calls. Let’s say for example you want f8, up from f4, so both people in your photo are in focus. That changes your shutter speed to 1/15th. The first thing you can do is use a tripod and ask them to hold still, or you can raise your ISO to 200 and get 1/30th or at ISO 400 for 1/60th.

Histogram Hopefully you are familiar with your cameras histogram and how it works. This is always a valuable tool when it comes to determining accuracy of your exposures. It is just as valuable here when learning to use flash and determine if your exposures are accurate.

Here is the histogram of a dark image. All the data is stacked on the left side of the histogram, the area for darks and black.

This histogram is more normal with tones evenly spread across from dark to light.

The histo lower left represents your typical flash picture. Normal flash exposure on the people and a dark background. Unlike the top histo image, there is data on the right ¾ area representing the info for the faces and lighter tones. Check your histograms when shooting test pictures to make sure that you have all the data you need for a proper exposure.