Using Multiple
Canon EX Flashes

The artificial lighting learning curve for most photographers starts with a built-in flash or external flash mounted above the viewfinder. The photographs they take with a single flash look flat and boring because they lack shadows to create the illusion of depth or look unflattering due to the position of the shadows to the side of the head and nose.

The first step a flash user can take to improve the the lighting is to change the direction of the light. Not by moving the light a few feet to one side - which only creates dark distracting shadow - but by simply raising it a foot or more above the lens. Raising the flash above the lens was a trick discovered by wedding photographers about 40 years ago. When the flash is raised straight up the head shadow disappears behind the shoulder the one created by the nose is hidden out of sight directly below it in a full face view or out of camera view in an oblique pose.

I learned to use a pair of flashes in 1972 when I went to work as an apprentice/assistant to Monte Zucker, the recognized as the best wedding photographer in the U.S. if not the world. He is the person who introduced the two-flash technique for wedding coverage. I've been using it ever since. For about 30 years I used a pair of Vivitar flashes, but a few years ago I switched to the Canon EX system using a pair of 580ex with my 20D.

Single flash using a bracket and diffuser

Raising the flash head above the lens by about 12 inches does two very good things. First it eliminates the chance that light will reflect off the subjects retinas causing the pupils to appear red (red eye). Secondly, the downward angle of the light throws the shadow from the head down and and directly behind a subject in front of the camera. Finally, the downward shadows under the cheeks define their shape in a flattering way and the nose shadow falls under the nose where it is not a distraction. Note: if you see nostrils in a photo your camera try a higher camera angle; the top of the nose is much more flattering.

There are many different flash brackets on the market ranging in price from $50 to over $300. The one shown above is a Stroboframe camera-flip bracket, which at $70 is one of the least expensive but most effective. Brackets which turn the camera put less strain on the base of the flash and keep it in exactly the same place regardless of whether the camera is being used in landscape or portrait mode. The flash has a Do-It Yourself (DIY) reflection diffuser which I made from two sheets of craft foam and some self-stick velcro; total time and cost 30 min and about $2. If you do nothing else as a result of reading my tutorials, please get a bracket and make a diffuser similar to this one. It will be the best investment you will make in the improvement of your lighting. I have an illustrated tutorial showing how to build one.

Many popular hot-shoe modifiers rely on the ceiling and walls to bounce some of the light to create soft fill. That works quite well when there is a low ceiling, but when there isn't one these devices are little better than bare flash. Over the years I've experimented with many different do-it-yourself modifiers and finally settled on a design which captures 100 percent of the output of the flash and bounces it forward. I explain why it works more effectively in this tutorial.

Canon E-TTL / E-TTL-II Flashes

TTL in its generic usage means Through-The-Lens exposure control. A TTL flash is linked intelligently to the camera which controls the the flash duration based upon the light detected from a pre-flash. If you have read my overview of the Canon flash system you know why I selected 580ex flashes rather than the other possible configurations. The remainder of this tutorial refers to 580ex, A 580ex/430ex combination will function similarly but the 430ex controls may differ from what is described here. This tutorial only covers E-TTL / E-TTL-II operation (ETTL mode indicated on flash). See the links at the bottom for a separate tutorials explaining the differences between Canon TTL, E-TTL and E-TTL-II and how to configure the Canon EX system for wireless M (manual) mode.

The Canon 580EX can wirelessly control and trigger other Canon flashes in a Master-Slave configuration. The lighting ratio is set via the master unit on the camera. The A:B ratio notation used by Canon does not produce the same results as the conventionsH:S ratios. As with manual flashes it is necessary to do some systematic testing to determine what A:B settings produce pleasing H:S ratios.

As with all flashes I recommend that the Canon TTL flashes be mounted on the camera with a flash bracket to keep the flash head above the lens at all times. To maintain the TTL signaling to the flash it is necessary to use the Canon Off-Camera Shoe Cord 2 to connect the flash to the hot-shoe of the camera.

Try To Forget What You Saw in The Manual

The Canon folks make a very fine flash system, but they don't appear to have clue how to use it. Exhibit A is this illustration from page 33 of the 580ex manual:

Note how the "A" and "B" flashes are each on opposite sides of the face. That's how the engineers at Canon apparently think a face should be lit. But that's horrible lighting for a face. Also notice that Canon apparently thinks we should buy a third 580ex or ST-E2 controller to trigger the off camera A and B flashes.

A more logical and economical arrangement is the one perfected by Monte Zucker about 40 years ago and used successfully by thousands of wedding photographers and other pros: a flash on a bracket as fill with a single off-camera light on a stand. When used with the Canon EX system the 580ex on the bracket which is connected to the hot shoe by the two-foot TTL extension cord 2 becomes the Group A MASTER in fill. The SLAVE flash on the stand, a 580ex or 430ex, is configured to operate the same channel as the MASTER and Group B as shown below:

Here is a shot taken with two 580ex with the diffusers shown above, but with the off camera light on the left rather than the right as shown in the diagram above:

Candid Shooting With Two Flashes

I learned flash photography with two flashes covering wedding receptions for Monte Zucker, who I assisted in the early 1970s. Back then we used twin-lens Rolleiflex cameras with a direct flash on a bracket above the camera and an identical flash with an optical slave on a modified medical IV stand, which had a heavy base with casters and was ideal for the job. Thirty-five years later I've yet to find a more effective technique for candids. I've changed to Canon 580ex ETTL flashes and added the foam diffusers but the technique and results are the same.

The IV stand I use for my off camera light (shown here) has five compact legs with casters. It has a footprint of only 25 inches. I just grab it with my free hand and wheel it around like a dance partner. For candid shots I'll often just park the off camera light behind and to the side of the people I'm shooting. The position isn't really very critical but the highlights the second light create nice separation of the subjects from a cluttered background. Also because the on camera flash is providing fill rather than a full blast of light the background distractions will also tend to be darker, also helping the more important foreground subjects to contrast.

These first two candid shots were taken at a party at my church for a departing pastor with the off camera light off to the side or behind without any attempt to use it for a specific pattern on the faces:

Here the three people were actually posing full face for someone else. I positioned myself to capture all of them in a more flattering oblique pose.
The off camera light to the left is providing the rim lighting.

When people are standing talking, or at a podium or microphone it is possible to predict where they will be looking and place the off camera flash to short light their face. Here I moved the light over to the left until I saw an oblique view of his face from behind the light stand, quite literally "seeing the light". Then I went over to the right until I saw his other oblique view and took the shot getting a nice flattering angle with studio-like short lighting.

This group wasn't even posed, they just happened to have arranged themselves in a perfect triangular composition. I just grabbed the off camera light and put it 45 degrees from the noses.

Configuring for A:B TTL

Setting up the MASTER flash for fill

  1. Set your camera to M (manual) mode with Shutter at 1/125 Aperture f/5.6 ISO100

  2. Connect a 580ex to the hot shoe using the hot shoe TTL extension cord 2 and set the wireless flash switch on base to the center MASTER position.

  3. Turn the flash on. If ETTL is not displayed in the upper left corner of the rear LCD press MODE until it is.

  4. Press the zoom button until you see CH and the number beneath it flash. There are four available channels. MASTER and SLAVE must be on the same channel. Turn the dial and select a channel other than 1 then press the center button on the dial.

  5. Press the zoom button until you see Ratio and off flashing. Turn the wheel the right until you see Ratio, on and A:B flashing. Press the button in the center of the dial.

The MASTER is now set. You should see the 8:1 to 1:8 ratio indicator appear. Turn the dial so the black indicator bar is under 1:1.

Important things to know
when configuring the MASTER flash:

With the Canon EX system the MASTER flash always defaults to Group A. To use wireless ETTL A:B ratios the slave must be be set to group B.

The ZOOM button controls four (4) different functions: 1) flash head zoom override; 2) communication channel selection; 3) wireless ratio on/off and A:B or A:B C; and 4) Main Flash on/off. Do not confuse #3 and #4, and take care to select A:B when setting the ratio mode (Step 5 above).

When the wireless selector on the base is set to MASTER the flash head will zoom to 24mm. That is done to ensure maximum line-of-sight communication with the SLAVE flashes. The zoom can be overridden by pressing ZOOM until the zoom setting begins to flash and turning the dial. To verify if MASTER and SLAVE are communication press the PILOT button on the MASTER. The MASTER will flash, followed by the SLAVE if they are communicating.

Please ignore / cross out pages 34-35 of the 580ex manual Fully Automatic Wireless Flash which will results in both flashes winding up in the "A" group and has left many new 580ex users confused and wonder why the @#*&%# ratios where not working. It is a useless mode of operation.

Setting up the off-camera SLAVE flash as "key" light

  1. Set switch on base to SLAVE

  2. Press the zoom button until you see SLAVE and A flashing. Turn the wheel to the right until the A changes to B

  3. Press the zoom button until you see CH and the number beneath it flash. Turn the dial and select the same channel as the MASTER then press the center button on the dial.

The SLAVE is now set as Group B. It will follow the instructions the the master

Shooting an exposure test

As with a single flash it will be necessary to shoot some test shots an adjust Flash Exposure Compensation (FEC) to get the highlights correctly exposed. I use and recommend a white terry washcloth as an exposure guide. It is as light as any textured clothing or other detail likely to be encounter in a scene, and unlike a smooth card it has texture which make it easy to see when detail is being lost due to over exposure. Bunch it up a bit so there are some folds and tonal gradation in the image.

It is not important that you have diffusers like mine for this test, but if you add them later, repeat the test because the amount of FEC needed will likely change.

Face a person full-face to the camera. Set the off camera light about 5ft away, 45 degrees from their nose and about a 18 inches higher than the eyes.

To "see the light" simply stand directly behind the stand, with it between you and the face if the subject. What you see from behind the light is what it will illuminate and where the highlights will be. What you can't see will be in the shadows. What you want to see is both eyes and a clean oblique view of the far side with the eye socket profiled. That will put the key light on the face with a short light pattern when you move and view the subject full-face or from the opposite side from the key light. Remember to show modeling on the face it is necessary to "shoot" into the shadows.

Important things to know
when positioning the SLAVE flash:

With the exception of the ST-E2 the EX MASTER flashes use visiblelight to send the coded pre-flash instructions to the SLAVEs. The small lens over CANON is the wireless sensor window (see pg. 4 of the 580ex manual) which must be pointed back towards the MASTER FLASH. Turn the front of the SLAVE flash base (sensor side) to face the camera flash, then turn its head to face the subject.

When the wireless selector on the base is set to SLAVE the flash head will zoom to 24mm. That is done to ensure maximum line-of-sight communication with the SLAVE flashes. The zoom can be overridden by pressing ZOOM until the zoom setting begins to flash and turning the dial. To verify if MASTER and SLAVE are communication press the PILOT button on the MASTER. The MASTER will flash, followed by the SLAVE if they are communicating.

The big red lens on the front of the flash is the Auto Focus (AF) assist lamp. It simply projects a grid pattern which helps the AF points of the camera focus. When the wireless selector on the base is set to SLAVE the AF Assist light will begin blinking. There is no way to turn it off. It serves as a "ready" light for the SLAVE on the side which winds up visible to the photographer. It will go out when the flashes are fired and come back on when the SLAVE is ready for the next shot. If it creates a problem it can be covered with black tape without affecting the operation of the flash.

With the SLAVE set stand about 8ft away directly in front of the subject and shot a test shot with ratio set to 1:1. Have your subject hold the white wash cloth or towel next to the face on the key light side.

Important things to know
when setting FEC:

If your camera body has an FEC button use it first for adjusting the FEC. Rebel 300D / 350D lack an FEC button. For those cameras, or if setting FEC on the flash is your preference, press the center button on the dial of the MASTER flash and dial it in.

FEC set on the camera or MASTER is applied to MASTER and SLAVE. There is no need to touch the SLAVE.

FEC set on the MASTER will override any entered on the camera body.

Examine the files in your PC editor (e.g., Photoshop). If the towel is not white with its texture intact (i.e. looking like it does by eye) adjust FEC, reshoot, and repeat until the correct amount of FEC is determined. The histogram spike from the towel will touching the right side of the graph. A simple way to get set the exposure is to increase FEC until the brighter parts of the towel turn black (over-exposure warning) in the playback then reduce the exposure by reducing FEC by 1/3 stop (one-click).

When I purchased my pair of 580ex flashes I shot the above test series using a white binder to determine what the A:B ratio settings actually produced. The off camera key light (Group B) illuminated only the right side, while the on-camera fill light (Group A) illuminated both sides of the binder. Both lights illuminated the gray card. My DIY reflection / diffusers were used on the flashes for the test. The yellow numbers are the A:B (Fill:Key) ratios. The small numbers are Photoshop eyedropper readings of the green channel. White balance is set automatically by the camera when a 580ex is used in AWB mode and it was very close to neutral.

As should be expected Ratios from 2:1 to 8:1 will appear flat because the camera axis fill of Group A (Fill) overpowers the off camera Group B (Key) Ratios of 1:1, 1:2, 1:4 and 1:8 will produce increasingly darker shadows and would be useful for portrait work.

Important things to note
when selecting A:B ratios:

With the Canon EX system the MASTER flash always defaults to Group A and he SLAVE must be be set to Group B.

When Group A is fill and Group B is the key light the Canon A:B ratios represent the SHADOW:HIGHLIGHT ratio, not HIGHLIGHT:SHADOW as for the past 100 or so years for portrait ratios. DOH!!! What the heck was Canon thinking?

I have a separate tutorial about this reversal of the lighting ratios, but just remember than with "neutral" fill on the bracket overlapping the off camera light the ratios between 8:1 and 2:1 all look the same: FLAT

Follow the Nose

One final point before moving on the three lights. The critical relationship in lighting is between the key light and the nose of the subject. As noted above, standing behind the off camera light while moving is as simple way to "see the light" without modeling lights. The key light will about 45 degrees from the subject's nose and higher than the eye line so the nose tip shadow falls down and over the top of the shadow side nostril.

Once a flattering short lighting pattern is set on the face any movement of the face will change it. So simply put, if the nose of the subject moves the key light must move also as if it were attached between the eyes with a rod. Note how the key moves as the facial angle to the camera changes from full-face to oblique. The angle of light-to-nose stays the same: about 45 degrees. Remembering that will greatly simply the question of where to put the key light.

Three Group A:B TTL

The Canon 580ex is designed to serve as the master controller for three groups of 580ex / 550ex / 430ex / 420ex slave flashes. The A and B groups are used as fill and key, respectively, with the master flash connected to the hotshoe always defaulting to group A. As shown in the test sequence above the ratio of B-to-A which is dialed in via the wheel on the back of the flash controls the H:S ratio. Group C is intended by Canon to serve only as a background light, not a light hitting the subject. That distinction is important because the C flash is not factored into the TTL exposure for the A:B groups and must be set from the master via a Group C FEC adjustment.

The sequence of shots below taken with three 580ex flashes configured as A:B + C shows the benefit of using dual flashes vs.the flat lighting obtained from a single flash and how the addition of a third flash to control the background can enhance and add another level of creative control.

Set-up: The Master flash "A" serving in the role of fill is mounted on a Stroboframe camera flip bracket and connected to the hotshoe via the hotshoe extension cord 2 and equipped with my DIY foam diffuser. The "B" group "key" flash, also equipped with a DIY diffuser is on the far right, hidden behind the improvised barn doors. I placed the key light behind and to the side of the Nativity figures because I wanted rim highlights to emphasize their overall shape rather than classic lighting patterns on the faces, and also so the manger which is the focal point would be in the most direct light and wind up brighter than the other figures which are mostly in shadow. The improvised barn doors were added to control spill. The flash in the middle just to the right of the table is the "C" group. aimed at the mantle.

I decided to shoot the figures with an A;B ratio = 1:4 and dialed it into Master on using its wheel. As is my usual practice a white terry washcloth was used to set the exposure. The foam diffusers I use alter the color temperature of the flash so I set custom white balance from a Kodak gray card. I also include a gray card and other calibration targets in exposure my test shots for checking and adjusting white balance during editing. The camera was set in M mode at f/8 and 1/250th sec. because I wanted to isolate the flash from the ambient light coming in from the windows on the right.

When the towel is exposed correctly everything else will be also. After setting the A:B ratio and establishing the A:B foreground exposure the background lit with with C group was adjusted visually via the flash exposure compensation (FEC) for group C. That is set on the master flash by pressing the center "set" button of the wheel until "C" flashes. I found that setting FEC for C to - 2 produced the tonal balance I desired.

The same set-up with three flashes, two flashes, and a singe flash. All the flashes were equipped with my DIY foam diffusers:

A:B and C

A:B Only (C group disabled)

A Only (Wireless TTL turned off)

After doing the shots above I started the fireplace and slowed the shutter from 1/250th to 1/8 sec. to capture the flame. It was late in the afternoon and the ambient light from the windows on the right wasn't a factor with the longer shutter time. These two shots taken in A:B+C mode differ only in their A:B ratio setting. The TTL exposure system in the camera automatically compensated for the change in shutter speed and ratio setting:

A:B = 1:2

A:B = 1:8

Disabling the Master Flash

When the 580ex is used as the master flash in the hot shoe it can be set so it does not contribute to the exposure. This capability would be used when two slave flashes set to A and B groups are used on stands with umbrellas. The test sequence below was shot with an A group slave flash to the left of a roll of paper towels and the B group to the right. Note that the lights were positioned so the middle of towels did not receive light from either flash. I do not suggest actually lighting anything that way, especially not a face.

The master flash is turned off by pressing the zoom button on the flash until the rays of light on the flash icon and the word "on" are blinking. The control wheel is then turned until "off" appears. The rays of light will disappear and the lighting bolt symbol indicating wireless control mode will start blinking and remain blinking during normal operation.

After turning off the master flash the A:B or A:B+C mode is selected by again pressing the zoom button until the words "ratio" and "off" flash. Turning the dial one click changes the display to "on" and "A:B". Turning it another click sets the master to A:B+C mode. After setting the desired mode a press of the set button in the center of the control wheel will change the display to show the bar graph used to set the ratio from 8:1 to 1:8.

E-TTL II vs Manual Power Mode

The beauty of the Canon wireless TTL system is its simplicity. Flash-to-subject distances don't matter with regard to exposure because the TTL automatically compensates both for setting the ratio and the exposure, even with three groups in play. As with any TTL system it is necessary to adjust the overall FEC to obtain the correct highlight detail exposure, but once that task is performed its ability to keep the exposure consistent regardless of the A;B ratio is something I find nothing short of amazing. However, when shooting several hundred directory portraits for my church with a pair of 580ex flashes I found Manual mode for the flashes to be superior to TTL. When I tried TTL the difference in clothing and complexion from person would change the flash output, requiring FEC adjustment to compensate. The biggest problem was the background, a plain shell white wall which made even slight variations in flash output very apparent.

Reverting to the method used with my trusty Vivitars I set both 580ex in manual mode at 1/2 power (for faster recycling). 5-1/2 is my arm span so I place the key light with the diffuser 5-1/2 feet and 45-degrees from nose of the subject. Setting the off camera flash for short lighting on the face is quite simple if you stand behind the flash stand and move it until a perfect oblique view of the face is visible. Fill is the master flash on the bracket, three steps backwards from the subject places the camera and fill light 8 feet away from the subject, the ideal distance for a head and shoulder portrait,with the relative distances of the 1/2 power key and fill producing a perfect 3:1 highlight:shadow ratio. A exposure test with the towel revealed that the best exposure was obtained at f/6.3 at ISO 100. The beauty of manual mode is that the exposure is always f/6.3 and every exposure, yesterday, today and forever is the same because the flash power and distance are the same for my standard portrait set-up.

The Equipment I Use

People frequently ask where to get the flash bracket, funky IV stand and other stuff pictured above. So here are the links to where you can find them.

For the on-camera MASTER Group A 580ex Flash:

Canon TTL Extension Cord 2

Stroboframe Bracket

Pitch-It Sr. IV Stand

For the off-camera SLAVE Group B 580ex / 430ex Flash:

Universal Umbrella Bracket

How to make the DIY Diffusers Find the materials to make them at Walmart in the craft section for about $2

Please let me know if any of the links above to other sites don't work. The mini-ball head shown in one of the shots was sold by Stroboframe when I got it, but I can no longer find it. It really isn't necessary if the universal umbrella bracket is used./Canon

More Canon Tutorials Here

Tutorials specific to Canon Flash

Holistic Concepts for Lighting
and Digital Photography

This tutorial is copyrighted by © Charles E. Gardner. It may be reproduced for personal use, and referenced by link, but please to not copy and post it to your site.

You can contact me at: Chuck Gardner

For other tutorials see the Tutorial Table of Contents