Gordon Lewis
Gordon Lewis

Gordon Lewis has been a passionate photographer and writer for more than 30 years. His first Canon was an F-1, purchased when he was a student in college and he has always owned Canon cameras and lenses since then.

Speedlite Tip Series, Part 1: Choosing the Right Flash

March 29, 2011

As long as a Canon EX-series Speedlite is connected to your EOS-system camera, the two operate as one… the flash and camera will automatically adjust themselves for correct synchronization, no matter what exposure mode you’re in.


This is the first part of a three-part series on Canon Speedlite flashes, written for the Canon Digital Learning Center by Gordon Lewis:

  1. Choosing the Right Flash
  2. Beyond the Instruction Manual (click to read)
  3. Multiple Flash and Lighting Ratios: A Wireless Primer (click to read)


One of the most valuable accessories you can have as photographer is a portable electronic flash unit, especially one that’s fully integrated with your camera’s exposure and autofocus systems. For Canon shooters this means a Canon Speedlite 220EX, 270EX, 430EX II, 580EX II (or any of their predecessors). If you doubt the value of owning an portable flash unit, consider the following facts:

  1. Ambient light isn’t always good light.
    As wonderful and convenient as available ambient light may be, sometimes there just isn’t enough of it, or it’s coming from the wrong direction, or it has a strong color cast, or it’s too harsh. Whenever this happens you’ve got three choices: You can either settle for a less than optimal photo, you can miss the shot entirely, or you can pull out a Canon Speedlite and correct the problem.
  2. Speedlites are powerful.
    Even the 220EX, the smallest of the line, has an ISO 100 guide number of 72 in feet (22 in meters) with enough coverage for a 28mm lens in full-frame format. That’s enough to give you a maximum shooting distance of 26 feet with a f/2.8 lens, at 100 ISO. The built-in flash units in Digital Rebels, xxD-series SLRs, and G-series compacts have a guide number closer to 43, which is almost two stops less. Compare that to the whopping maximum guide number of 190/feet that the 580EX II delivers at 105mm coverage. More light output means a greater maximum range and the ability to use smaller f-stops for greater depth-of-field. It also provides the ability to bounce the light off reflective surfaces for a larger and therefore softer light source—which, come to think of it, is another thing you can’t do with a built-in flash. I’ve provided a few examples here for your reference.
  3. Speedlites are a consistent, daylight-balanced light source.
    Canon Speedlites are designed to emit light at the same color temperature as the mid-day sun. That means you can add flash to a daylight-lit photo without drawing attention to your secondary light source. If you prefer something warmer, you can adjust the light balance in-camera, by taping a color gel over the flash reflector, or by adjusting your Raw files. Whatever the case, you can always be confident that you’re working with a consistent light source.
  4. Speedlites freeze subject motion.
    When flash is the primary source of illumination, its short duration becomes your effective shutter speed. Speedlite flash durations are typically 1/800 second or shorter. That’s fast enough to freeze subject motion and eliminate camera shake, even with non-IS lenses. Assuming accurate focus, the result is more consistently sharp photos in low light.
  5. Speedlites reduce your reliance on high ISOs for low-light photography.
    Canon EOS digital SLRs are renowned for their ability to produce low-noise images at high ISOs. That said, even Canon D-SLRs have their limits. Having a Speedlite on hand to provide an extra stop or two of light can mean the difference between shooting at ISO 800 vs. 3200 or shooting at f/5.6 instead of f/2.8.
  6. Speedlites are fully integrated with your EOS camera.
    As long as a Canon EX-series Speedlite is connected to your EOS-system camera, the two operate as one. This means that the flash and camera will automatically adjust themselves for correct synchronization, no matter what exposure mode you’re in. If there’s not enough light for the lens to focus properly, the flash will automatically emit a focus-assist beam onto the subject to help provide sufficient light for correct focus. If the flash exposure is too bright or too dark, you can adjust it from the camera, the same way you would any other type of exposure. The same applies to the ambient light exposure. In fact, you can adjust the flash and ambient exposures separately from each other to achieve exactly the balance you want.

    Your EOS SLR can even tell when you’re using flash in bright light. Based on the assumption that you’re using flash to lighten shadows rather than as the primary light source, your camera will automatically reduce the flash intensity so it won’t overpower the ambient light. Since DSLRs give you instant visual feedback on exposure, you’re never shooting blind. If you don’t like what you see, it takes only seconds to adjust the exposure to suit your preference.

Flash Fundamentals (for those new to flash photography)

Some photographers get a little intimidated by electronic flash units because the short duration of their illumination makes them seem hard to control, and you can’t see flash illumination in the same way you can see continuous ambient light. The fact is that a flash unit is basically a very simple device. Think of it as a light bulb that has a fixed output. Since the output is fixed, the only way to control exposure is by controlling the amount of time the light bulb is on. Flash Duration refers to the length of time a flash illuminates during an exposure.

If the maximum duration is 1/1000 second, then 1/2000 second would provide half as much light, 1/4000 would provide 1/4th as much, and so on. The camera and Speedlite automatically control flash output by reading the amount of light reflected from your subject and adjusting the duration to match your ISO and f-stop settings. Your camera’s shutter speed is not a significant factor in flash exposure because the flash duration is so much shorter than the shutter duration. Your shutter speed does affect the ambient light exposure, however. The longer the shutter is open, the brighter the areas not lit by flash will be. The reverse is also true: the shorter the shutter speed, the darker the ambient light exposure.

Even Canon’s wireless flash system operates on a simple principle: The flash units use brief pulses of light to communicate with each other. As long as their sensors are within range of each other and within each other’s line-of-sight, they will flash in sync at the output you set. Better yet, you can adjust the output at your camera or the master flash unit without having to walk over to each separate flash. Whether you’re using one flash or many, portable flash lighting doesn’t get much easier than this.

So now that you’re familiar with the benefits of Speedlites in general, let’s turn to specifics: Which one is right for you? Well, if you’re looking for something small, lightweight, inexpensive and easy to use, the entry-level Speedlite 220EX and the new Speedlite 270EX are the obvious places to start.

Speedlite 220EX

The Speedlite 220EX is handy even if your camera has built-in flash. Aside from providing nearly twice the light output, it’s self-powered by four AA-size batteries, and therefore places no drain on your camera battery. It also overcomes one of the most serious limitations of built-in flash: The fact that they are so close to the lens axis. Under some conditions this can result in “red-eye,” caused by light reflecting off a subject’s retina and back into the lens. With large lenses, especially those that have a lens hood, using a pop-up flash can cause the lens to cast a shadow at the bottom of the frame. The 220EX positions the flash head far enough way from the lens axis to greatly reduce red-eye and lens shadows. For even more flexibility, Canon’s optional OC-E3 off-camera shoe cord allows you to use the 220EX off-camera, which makes the 220EX perfect for quick and easy macro lighting. The 220EX even has a high-speed sync feature that allows you to use shutter speeds faster than the normal sync speed—perfect for flash-fill at close distances.

The 220EX has limitations, of course. Because it has no bounce feature, the flash is always pointed toward the subject, providing direct flash illumination. Bounce flash would only be possible if you remove the flash from the camera, and use the optional Off-Camera Shoe Cord OC-E3. Another limitation is that 220EX’s reflector has a fixed 28mm angle of coverage, which makes it less efficient with longer focal-length lenses. (With cameras like the EOS Digital Rebel series or EOS 50D, the Speedlite 220EX can cover wide-angle lenses down to 18mm.) Finally, the 220EX is also not compatible with Canon’s wireless E-TTL flash control system. If you’re looking to step up from the built-in flash, but want something affordable and compact that can also bounce and zoom the flash head, Canon has great news for you: the Speedlite 270EX.

New: Speedlite 270EX

The Canon Speedlite 270EX is a brand-new lightweight flash unit that adds several significant new features, but in a size and form factor that’s especially appealing to owners of lightweight cameras. This Speedlite allows the user to manually pull out and zoom the flash head, narrowing the flash’s coverage to 50mm (approx. 32mm on an APS-C camera such as the EOS Digital Rebel series or EOS 40D, 50D, etc), for more distance range and effective power. It also allows tilting the flash head upward up to 90°, for bounce flash in typical indoor situations, concentrating more light upward when it’s needed most.

Its guide number is 72 (in feet, at 100 ISO), and expands to 89 (in feet) when the flash head is pulled out to provide more concentrated coverage. This is again essentially double the power of a built-in flash, and especially with telephoto lenses means easier shooting, without lots of size, weight and cost.

With only a simple on-off switch on its exterior, it may appear at first glance that the Speedlite 270EX offers almost no user control. However, this isn’t the case — if used with any of Canon’s recent Digital SLRs (EOS Rebel XS/XSi, EOS 40D/50D, EOS 5D Mark II, and the top-of-the-line “Mark III” cameras), their new Flash Menu feature allows you to control any EX-series Speedlite via the camera as well as the flash. When attached to any one of these models, the Speedlite 270EX allows you to select 2nd-curtain flash sync, manual flash mode (from full to 1/64th power, in 1/3-stop increments) Flash Exposure Compensation, and your choice of evaluative or average flash metering.

Advanced new circuitry allows the Speedlite 270EX to run off of only two AA-size batteries, yet still provide faster recycle time than the 220EX does with four batteries. Side-benefits of using two batteries are an even more compact design, and lighter weight — in spite of its zooming and bouncing capability. This new Speedlite is a terrific choice for users whose needs exceed those of a built-in flash, and it’s a great and light-weight option for EOS 5D Mark II users (which have no built-in flash) when a bit of fill-flash is needed outdoors, or for fast indoor shots with flash.

Speedlite 430EX II

Although it’s approximately double the size and weight of the 220EX, the Speedlite 430EX II offers more than double the maximum output and significantly more flexibility. This comes largely by virtue of its flash head, which automatically adjusts to your lens’ focal length within a range of 24-105mm, even if you’re using a zoom. The 430EX II also comes with a built-in wide-angle diffuser that can increase the angle of coverage to 14mm. Together, these features ensure optimum output and coverage whether you’re shooting wide angle or telephoto.

The 430EX II’s flash head also tilts (from directly forward to 90˚ up) and rotates (0 – 180˚ left or 0 – 90˚ right). This allows you to aim the flash head up at the ceiling or toward a nearby wall for bounce lighting, and also permits easy upward bounce flash when you’re shooting a vertical shot. All it takes to move the flash head is a single push of a single button, located on the side of the head.

The Speedlite 430EX II has its own Custom Functions, allowing the photographer to modify various aspects of its operation. Example: ever turn off your flash to conserve battery power, only to forget to turn it back on again? The 430EX II’s auto-off feature solves this problem by automatically turning the flash off after a predetermined amount of time (the available range is from 1.5 to 15 minutes). Tap on the shutter button and the flash immediately powers up again. This can save battery power when you're shooting  flash pictures over a long period of time. You also have the option of using a Speedlite Custom Function to disable auto-off if you want to make sure the flash is always on and ready to fire. Other Speedlite Custom Functions include:

  • Time before Auto Power Off when used as a Slave Unit (60 min. or 10 min.)
  • Auto Zoom matched to camera’s image sensor size (on or off)
  • AF-Assist Beam (on or off)
  • Modeling Flash (on or off)
  • LCD Panel Display When Shutter Button Pressed Halfway (maximum flash range or aperture)

Along with the aforementioned automatic features, the 430EX II allows you to set the power output manually from full to 1/64 power, in 1/3-stop increments. Manual settings are useful for when you need a specific and consistent output, regardless of subject distance or brightness. They’re also handy for when you’re using the 430EX II as a “slave” unit. This photographic term refers to a flash unit off the camera, that is triggered by something other than a direct connection to the camera. With Canon’s wireless flash system the “master” unit that controls the slaves can be either a 580EX/EX II or a Canon Speedlite Transmitter ST-E2 infrared trigger. The 430EX II doesn’t have the circuits necessary to be a master flash unit.

Speedlite 580EX II

The fact that the Speedlite 580EX and 580EX II can function as either a slave or a master flash unit is one of the most significant advantages they has over the 430EX/EX II. When used as a master, the 580EX/EX II can wirelessly control up to three groups of flash units (A, B, and C), with multiple flash units in each group and with full exposure automation. Although the optional Canon Speedlite Transmitter ST-E2 will also work as a master unit, it can control only two channels, and the infrared light it emits has a more limited range. That’s why if you want to take full advantage of Canon’s wireless flash system, the 580EX II is the best way to do it. Try starting out with a 580EX II and then adding more units according to how much output and flexibility you need.

That brings up another major benefit of choosing the 580EX II: power. The 580EX II can provide nearly twice the light output of the 430EX II. The only other way to get twice the 430EX II’s output at the same distance would be to add a second flash unit. When you look at it that way, one 580EX II is considerably smaller and more economical than two 430 EX IIs. It’s also a lot more versatile. Among the 580EX II’s many other advanced features are:

  • A flash head that rotates 180° in both directions
  • A moisture-sealed battery compartment and metal flash foot with quick-lock lever
  • A built-in PC connection for use with any compatible flash trigger or camera
  • A built-in external auto-exposure sensor that enables to 580EX II to be used in traditional, non-TTL auto flash exposure mode
  • A built-in pull-up reflector to fill-in the shadows that result from ceiling bounce lighting
  • 14 Speedlite Custom Functions (vs. 6 for the 430EX II)
  • Ability to manually adjust light output from full to 1/128 power, in 1/3-stop increments. These are just the highlights, but based on these features alone the Speedlite 580EX II is the obvious choice for advanced and professional photographers. In fact, because it’s Canon’s most powerful and versatile Speedlite, it’s a no-brainer for anyone with a serious interest in flash photography.

Integration and Control

One final thing to keep in mind is that because Canon Speedlites are so closely integrated with your camera, there are additional features such as Flash Exposure Lock, Exposure Compensation, and Exposure Bracketing that can be set either on the flash or on the camera. Suffice it to say that Canon’s Speedlite system offers you more ways to control flash lighting and exposure, more easily than ever before. For more information and ideas on what you can do, check out the next two tutorials in this series:

The CDLC contributors are compensated spokespersons and actual users of the Canon products that they promote.

All images are copyright Gordon Lewis


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