Guide to Canon EOS Speedlite System

by Bob Atkins

Photography is about creating images with light. For indoor, night, fill light, or certain special effects, using electronic flashes to generate light becomes an important component in modern photography. Canon flash units are called “Speedlites” by Canon. There are currently three shoe mount Speedlites (220EX, 430EX II and 580EX II) as well as two specialty macro flash systems (MR-14EX and MT24EX). While Canon consumer and prosumer DLSRs (such as the Digital Rebel Series and the EOS 40D/50D) have a small built-in flash, the pro series cameras such as the EOS 5D, 5D MkII and the 1D and 1Ds series cameras do not and so require the use of an external flash, often a hotshoe mounted Speedlite.

The intro image demonstrates the size differences amongst the 220 EX, 430EX II, and the 580EX II.

Flash Basics

Flash illumination is produced by an electrical discharge though a glass tube filled with gas (often Xenon) at low pressure. This is a short burst of light, typically lasting 1/1000s or so. The amount of light which can be emitted is controlled by the size of the flash tube and the energy of the discharge. If full flash power is not needed, the discharge is “quenched” early. For example if the full flash takes 1/1000s and you only want 1/10th of that amount of light, the discharge is stopped after only 1/10000th second. The automatic metering system in the camera determines when the flash needs to be stopped to give the correct exposure. The color temperature of most flashes matches daylight, so they can be used for outdoor work to fill in shadows without the results showing “mixed lighting” effects.

Canon Speedlite and Flash System Terminology

Speedlite

“Speedlite” is the term used by Canon for its flashes. Not to be confused with “Speedlight”, the term used by Nikon for its flashes!

TTL metering

TTL stands for “Through The Lens” flash metering. In this mode (used only with film cameras), the light reflected from the film is measured by sensors in the base of the camera. When enough light has been received the flash is cut off.

A-TTL metering

A-TTL stands for “Advanced Through The Lens” flash metering. In this mode a weak pre-flash is issued, either from the flash tube when in bounce mode or from an IR emitter in normal mode. The intensity of the returning signal is used to estimate subject distance and to select an aperture for program operation. Final exposure is determined by measuring the amount of light reflected off the film, cutting off the flash when enough light has been measured. Again this mode is only available on film bodes, not digital.

E-TTL metering

E-TTL stands for “Evaluative Through The Lens” metering. In this mode the flash tube emits a pre-flash and the camera’s evaluative metering system is used to determine flash exposure. This not only allows more accurate flash metering, but also enables FEL (flash exposure lock) to be used, since the exposure is determined prior to the main flash firing. In addition E-TTL is required for digital SLRs because the digital sensor does not reflect light in the same way as film does and so TTL and A-TTL metering cannot be used. Only the “EX” series speedlites support E-TTL metering. The earlier “EZ” series speedlites only support TTL and A-TTL and so a cannot be used for auto flash operation with any EOS digital SLR.

E-TTL II

E-TTL II is much like E-TTL except that the focus distance returned by the lens may, in some circumstances, be used in determining flash exposure. Since E-TTL II is a camera body based modification of E-TTL, all E-TTL capable speedlites can also operate in E-TTL II mode when used with an E-TTL II compatible body.

FEL

FEL stands for “Flash Exposure Lock”. It’s available on most both film and digital SLRs made after the EOS Elan II in 1995

FEB

FEB stands for Flash Exposure Bracketing. This is a function built into some high end speedlites (such as the 550EX, 580EX and 580EX II) which allows three images to be taken with different flash exposure compensation settings. It’s like AEB (auto exposure bracketing) for continuous lighting.

FP sync

FP actually stands for “Focal Plane”, though some people think of it as “Fast Pulse” or “Flash Pulse”. In FP mode the flash tube emits a series of very fast flash pulses so that it appears to the film or sensor as a continuous light source rather than a very fast flash. This allows the use of fast shutter speeds, though it does reduce the effective power of the flash.

Sync Speed

This is the fastest shutter speed at which the first curtain of the shutter fully opens before the second curtain closes. At speeds faster than the sync speed, the shutter actually forms a slit which moves across the image. The faster the shutter speed, the narrower the slit. If you make a flash exposure at 1/500s when the maximum sync speed of the camera is 1/250s, half the frame will be black. If you want to shoot using flash at 1/500s with that camera, you have to use FP mode (see above) if the speedlite supports it.

Maximum Sync Voltage

When a flash charges, a voltage appears between the center pin and the edge contact on the hot shoe foot. To fire the flash, a circuit in the camera connects these two contacts. The maximum sync voltage is the highest voltage that the camera can connect without damage. This also applies to the voltage across the PC connector socket. On many earlier Canon EOS bodies this was 6 volts, but on more recent models this has been increased to 250 volts. Canon speedlites conform to the 6 volt standard, but some 3rd party flashes (especially general purpose flashes not designed for EOS use) can have sync voltages of up to 250 volts, and a few are even higher.

Unfortunately Canon seem to hide the value of the maximum sync voltage for their SLRs somewhere in small print in the manual and sometimes they don’t list it at all, so n official comprehensive list doesn’t exist. What’s worse is that if you call their tech support you’ll often get a “6v” answer even if it’s actually 250v, and I assume that’s because the support reps like to play it safe if they aren’t sure. As far as DLSRs go, as far as I can tell, the D30, D60, 10D and original digital Rebel all have a 6v limit, while the Digital Rebel XT, the EOS 20D and newer DSLRs have a 250v limit. Despite some internet postings to the contrary, it appears that the PC socket and hot shoe sync voltages are the same.

The closest thing I have to an “official” list is from Chuck Westfall’s “Tech Tips” column from March 2007 (http://dirckhalstead.org/issue0703/tech-tips.html). It states the following:

Canon Digital SLRs safe up to 250 volts: EOS-1D Mark II N, EOS-1D Mark II, EOS-1Ds Mark II, EOS-1D, EOS-1Ds,EOS 30D, 20D, 5D,EOS Digital Rebel XTi, XT (400D/350D),EOS D6000/D2000, Kodak DCS560/DCS520 (circa 1998),EOS-DCS series (circa 1995).

I would assume that the 250v limit also applies to more recent DSLRs such as the 5D MkII, the 1Ds MkIII, the 1D MkIII, the EOS 50D, the Rebel XS and the Rebel XSi

Canon Digital SLRs safe up to 6 volts: EOS 10D, D60, D30,EOS Digital Rebel (300D)

Canon 35mm SLRs safe p to 250 volts: EOS-1V, EOS-1N, EOS-1, EOS 3

Canon 35mm and IX240 SLRs safe up to 6 volts: EOS 650, 620, 630, RT, 850, 750, 700, EOS Rebel Series, EOS Elan Series, EOS 10s, A2E, A2, EOS IX, IX Lite,T90

Second Curtain Sync

In normal flash operation the sequence of operation is as follows:

1. The first shutter curtain opens fully.
2. The flash fires (which may take only 1/10000s)
3. The shutter stays fully open for the rest of the exposure
4. The second shutter curtain moves across and stops the exposure.

In second curtain sync the sequence of operation is as follows:

1. The first shutter curtain opens
2. Nothing happens during the rest of the exposure until…
3. Just before the second curtain starts, the flash fires
4. The second curtain moves across and ends the exposure.

What’s the difference? Well say you have a moving car at night. In normal operation (first curtain sync) you get a sharp flash exposed image with the car lights trailing off ahead of the car during the remaining time the shutter is open. This doesn’t look right. What looks better is if the light trails are behind the moving car, and that’s what you get when using second curtain sync. You get the light trail during the regular exposure, plus the sharp flash image at the end rather than the beginning.

PC connector

Not a Personal Computer connection as you might think, but a flash connector called a “Prontor/Compur” socket. “Prontor” and “Compur” are names of early shutters. Some think PC stands for “Push Connector”, but it doesn’t! PC flash connections are used for external flashes such as studio strobes. It’s actually an awful connector because the plug either falls out of the socket or gets stuck in it. It’s just a push fit, but were stuck with it now. There is a variant called a “Screwlock” PC connector and socket which gives a more positive connection because there’s a locking ring that screws into a compatible socket. Most of the Canon SLRs and DSLRs with a PC socket have “Screwlock” sockets.

Guide Number – GN

Guide Number is a measure of how much light a flash emits. It can be used to manually set the correct aperture for proper exposure based on the distance between the flash and the subject. To find the aperture to use you divide the GN by the distance. So if the flash is 10ft from the subject and the GN is 40 (ft at ISO 100), you would set the aperture to f4 at an ISO 100 setting. The Guide number doubles when the film speed is increased by 2 stops, so that a GN of 40 (ft at ISO 100) is equivalent to a GN of 80 (ft at ISO 400). Guide numbers assume a direct path between the flash and the subject. If the flash is bounced off a wall or ceiling, all bets are off and the effective GN will be much lower.

Type “A” and “B” SLR bodies

The type “A” and “B” designations are sometimes used by Canon to differentiate between SLR bodies that support E-TTL (type “A”) and those that do not support E-TTL (type “B”). There are some additional subgroups, but basically it’s a measure of whether some sort of E-TTL is supported or not. All current EOS SLRs (both film and digital) are type “A” and all digital SLRs (except for the very early DCS3 and DCS1 models) are type “A”. All film bodies released before the EOS Elan II are type “B” and don’t support E-TTL.

Current Canon Speedlites

Canon Speedlite 220EX

Canon Speedlite 200EX

The Canon Speedlite 220EX Flash, $125 (review) is the least expensive of the Canon Speedlites and has fewest features. It’s a simple speedlite with fixed head that neither tilts, swivels nor zooms. There is no option for manual power adjustment, though of course the camera body can apply FEC (flash exposure correction). Despite being Canon’s most basic Speedlite, the 220EX is fully compatible with E-TTL II operation and allows both FEL (flash exposure lock) and FP (high speed sync) on compatible Canon EOS bodies. The 220EX will operate in standard TTL mode using “off the film metering” with film based DSLRs which do not support E-TTL.

The Guide Number of the 220EX is 22m or 72ft (at ISO 100), giving it a range, for example, of up to about 13ft at f5.6 at ISO 100, or 26ft at f5.6 at ISO 400. The 220EX has no provision for wireless operation. There is an AF assist beam which is projected when the light is too low for normal AF operation. It’s linked to the center AF zone of the camera and should be good to about 16ft. Recycle time depends on how much of the flash power is used during the exposure, but even for full power flash (where all of the power is used), it’s a relatively quick 2.5 seconds.

The main advantages of using an external speedlite like the 220EX is that it gives you more power than the built in flash on any camera (which typically have a guide number of around 12m @ ISO 100), it gets the flash head slightly higher above the axis of the lens (which may result in slightly less “red-eye”). You can also move the flash up to a couple of feet from the camera using the Canon off-camera shoe cord for even better results. Using an external flash also saves you from drawing flash power from the camera battery and so you can get more flash images per battery charge. The 220EX uses 4 “AA” sized batteries (alkaline or rechargeable) and can provide between 250 and 1700 flashes per battery set according to Canon.

Canon Speedlite 430EX II

Canon Speedlite 430EX II

The Canon Speedlite 430EX II Flash, $250 (review) was introduced in the fall of 2008 and is a pretty full featured flash. The head zooms, tilts and swivels and the 430EX II can operate as a slave flash (but not a controller) in the Canon wireless speedlite system.

Via an LCD panel and push button controls on the rear, full manual control is possible. The head can be zoomed to 24mm, 28mm, 35mm, 50mm, 70mm, 80mm and 105mm. There is also a manually operated “Wide panel” which pulls out and which expands the coverage to that of a 14mm lens. The zoom head can be programed via a custom function to take into account the “digital multiplier” factor of lenses used on a crop sensor camera. If the flash then detects a crop sensor camera, the head is zoomed to provide the correct angular flash coverage for the focal length being used. The output can be manually set to full, 1/2, 1/4, 1/8, 1/16,1/32 or 1/64 power and in auto flash mode the 430EX II can be set for up to +/- 3 stops of FEC (flash exposure compensation), set in 1/2 or 1/3 stop steps. If FEC is set on both the speedlite and camera, the speedlite setting take precedence. The 430EX II can be manually set in a high speed sync (FP) mode and for second curtain sync.

The flash guide number (m @ ISO 100) varies with the zoom setting:

• 24mm GN=23
• 28mm GN=26
• 35mm GN=32
• 50mm GN=35;
• 70mm GN=38
• 105mm GN=43

Canon Speedlite 430EX II

The AF assist beam of the 430EX II covers all 9 focus points of cameras such as the Digital Rebel XSi. EOS 50D and EOS 5D. Range is approximately 32ft for the center AF point and 16ft for the outer points.

On compatible cameras with a DOF preview button, depressing the DOF preview in flash mode will put the 430Ex II into “modeling flash” mode, where it will rapidly strobe for about 1 second to allow you to observe where any shadows will fall.

When the flash fires, color temperature information is transmitted to compatible Canon EOS DSLRs. This color temperature information is then used to set white balance if the WB setting on the camera is “auto” or “flash”. This can reduce image color variation between flashes.

The 430EX II is powered by 4 “AA” cells and Canon specify that between 200 and 1400 flashes can be obtained from one set of batteries. Recycle time after a full power flash is approximately 3 seconds.

The Canon Speedlite 430EX II is probably has all the functions that the average photographer will need. Its major limitation for advanced use is that it cannot be used as a wireless controller in a multiple flash system. It can only operate as a slave, and so a controller capable speedlite (550EX, 580EX, 580EX II) or a speedlite transmitter ST-E2 must be mounted on the hotshoe in order to use a 430EX II off camera for lighting fill. Unlike some Nikon and Sony DSLRs, Canon DSLRs cannot use their built in flash as a wireless flash controller. The 430EX II also lacks the ability to be run from an external power source, which may be required to shorten recycle time and extend flash capacity is high use situations (e.g. weddings).

Canon Speedlite 580EX II

Canon Speedlite 580EX II

The Canon Speedlite 580EX II Flash, $395 (review) has all the features of the 430EX II, but adds a significant number of new functions. The 580EX II can act as a master controller in a wireless flash system, it can be powered by an external power pack for faster recycling and more shots than using the internal “AA” batteries. It has a PC socket for wired operation off camera and a stroboscopic flash option. It also has a small built in “bounce card” which reflects a small amount of light forward when the flash head is tilted up for bounce flash operation.

The 580EX II has more power then the 430EX II and the guide number (m @ ISO 100) varies with zoom setting as follows:

• 14mm GN=15
• 24mm GN=28
• 28mm GN=30
• 50mm GN=42
• 70mm GN=50
• 80mm GN=53
• 105mm GN=58

The 580EX II has about 35% more reach than the 430EX II.

Canon Speedlite 580EX II

New on the 580EX II is a external metering mode which does not use the camera’s metering circuit for exposure control. Instead a sensor on the 580EX II measures the amount of light being reflected back from the subject and controls the flash output accordingly. Of course this mode has been used on “semi-automatic” flash systems for decades as an “auto thyristor” mode. In the 580EX II it’s taken one step further when you’re using an EOS body such as the 1Ds MkIII, which tells the speedlite what ISO setting is in effect and what aperture is being used. With other cameras the ISO and aperture must be entered manually. There is no preflash in the external metering mode, which may be an advantage in some circumstances.

The 580EX II has 14 custom functions:

C.Fn-00: Distance indicator display (ft/m)
C.Fn-01: Auto Power Off (enabled/disabled)
C.Fn-02: Modeling Flash
C.Fn-03: FEB (Flash Exposure Bracketing) auto cancel
C.Fn-04: FEB sequence
C.Fn-05: Flash Metering Mode
C.Fn-06: Quickflash with continuous shot
C.Fn-07: Test firing with autoflash (enabled/disabled)
C.Fn-08: AF-assist beam firing
C.Fn-09: Auto zoom for sensor size (enabled/disabled)
C.Fn-10: Slave auto power off timer
C.Fn-11: Slave auto power off cancel
C.Fn-12: Flash recycle with external power source
C.Fn-13: Flash exposure meter setting

Canon Macro Ring Lite MR-14EX

Canon Speedlite MR-14EX

The Canon MR-14EX Macro Ring Lite, $445 (review) is a specialty macro flash with a circular light producing area which fits around the lens. There are actually two curved flash tubes in the MR-14EX and the power to each can be varied to produce anything from even illumination to a 6 stop difference. The MR-14EX is compatible with both TTL and E-TTL and so can be used with both film and digital SLRs.

The MR-14EX can also act as a master controller for a wireless flash system and can accept power from an external high-capacity battery pack. In addition to the flash tubes, which can also be used as modeling lights, there are two built in incandescent lamps which can both aid focusing and also act as modeling lights. It supports both FEC and FEB.

Canon Macro Twin Light MT-24EX

Canon Speedlite MT-24EX

Similar in concept to the MR-14EX, the Canon MT-24EX Macro Twin Lite Flash, $659 (review) has two flash tubes, one of which mounts on each side of the lens. They can be swiveled around the lens, aimed separately or even detached and mounted off camera. Each flash tube can be manually controlled over a 6 stop range. The MT-24 EX is compatible with TTL and E-TTL and so can be used with both film and digital SLRs. Like the MR-14 EX, the MT-24EX can act as a master flash controller in a wireless speedlite setup.

Canon Off Camera Shoe Cord OC-E3

Canon Off Camera Shoe Cord OC-E3

The Canon Off Camera Shoe Cord OC-E3, $70 allows fully automatic operation of any speedlite up to about 2ft from the camera. It is compatible with all Canon EOS cameras except for the 630 and RT. All functions are retained including full E-TTL II operation with cameras and speedlites that support E-TTL II. One end of the cord mounts in the camera hotshoe and the speedlite mounts in the hotshoe foot at the other end of the cord. The foot is threaded (1/4-20) so that it can be mounted on a tripod. The OC-E3 is an improvement of the now discontinued Off Camera Shoe Cord 2. It has better dirt and moisture sealing and has a sturdier (metal) foot.

Canon Speedlite Transmitter ST-E2

Canon Speedlite Transmitter ST-E2

The Canon STE2 Speedlite Transmitter, $200 isn’t actually a flash, but it mounts on the camera hotshoe and acts as a mater controller for a wireless flash system. It has an AF assist light built in, but no flash tube. You could just use a 580EX II as a controller of course, but the ST-E2 is smaller and lighter and cheaper ($220 vs $420 in 02/09). The ST-E2 can control two groups of flashes, while the 580EX II can control three.

Discontinued Canon Speedlites

Note that “Film only” indicates that automatic operation is available on when used with film based SLRs. With digital SLRs only fully manual operation (based on Guide Number) can be used with these Speedlites.

Canon Speedlite 160E

This was an early speedlite. Very basic, in fact so basic it didn’t even have an on/off switch! Fixed flash head, TTL only. Powered by a 2CR5 battery. Film only

Canon Speedlite 200E

A replacement for the 160E with a little higher power and powered by 4 “AA” cells. TTL only. Film only

Canon Speedlite 300TL

Originally introduced for use with the Canon T90 camera, the 300TL is also compatible with EOS SLRs. Tilt and Swivel head with zoom (24-85mm). Supports TTL, A-TTL, FEL plus two manual power settings (full and 1/16 power). Powered by 4 “AA” cells. Film only

Canon Speedlite 300EZ

Fixed flash head with 28-70mm zoom. Supports TTL and A-TTL modes. Powered by 4 “AA” cells. Film only

Canon Speedlite 420EZ

Tilt and swivel flash head with 24-80mm zoom range. TTL, A-TTL and variable manual power (full to 1/32 power). Powered by 4 “AA” cells. Film only

Canon Speedlite 430EZ

Tilt and swivel head with 24-80mm zoom. TTL, A-TTL and variable manual power (full to 1/32 power). A replacement for the 420EZ with slightly more power and the ability to use an external power pack (the Canon Transistor Pack E). Powered by 4 “AA” cells. Film only

Canon Speedlite 540EZ

Most powerful and flexible speedlite that doesn’t support E-TTL. Tilt and swivel head with zoom (24-105mm). Supports TTL, A-TTL and variable power manual (full to 1/128 power). Stroboscopic operation to 100Hz. Flash exposure compensation of +/- 3 stops. Film only

Canon Speedlite 380EX

A mid range speedlite which supports E-TTL as well as TTL and A-TTL. It has a head that can be tilted for bounce, but it does not swivel. The head zooms from 24-105mm. No manual power control. FEL and FP are supported with compatible cameras. Usable with film and digital SLRs. No wireless capability.

Canon Speedlite 420EX

An upgrade of the 380EX to include a flash head that both tilts and swivels. Zoom range 24-105mm. Can act as a wireless slave. Supports TTL, A-TTL and E-TTL operation, but no manual power control. Has a modeling light, FEL and FP with compatible cameras. Usable with film and digital.

Canon Speedlite 430EX

An update of the 420EX with slightly more power and variable power manual flash operation (full to 1/64 power). Flip out diffuser expands flash coverage to 14mm. Usable with film and digital. As of February 2009, the 430EX is still listed on the Canon USA website, though clearly it has been replaced by the 403EX II. There’s not a huge difference between the two models. The II version has a sturdier (metal) foot and with compatible DSLRs it can be configured from the camera as well as by using its own LCD panel. The 430EX II also has about a 20% faster recycling time than the 430EX and offers manual control in 1/3 stop steps.

Canon Speedlite 550EX

Canon “top of the line” flash at the time it was introduced, the 500EX can act as a mater controller in a wireless flash system. Variable manual power (full to 1/128 power) as well as TTL and E-TTL operation. Supports FEL, FP, FEB and modeling light operation with compatible cameras. The 550EX has a high voltage connector for use with an external battery pack. Usable with film and digital.

Canon Speedlite 580EX

An update of the 550EX, the 580EX offers slightly more power and some user interface improvements such as a control wheel. It has a faster recycle time than the 550EX as well as being physically slightly smaller and lighter. Usable with film and digital.

Canon Macro Ring Lite ML-3

The ML-3 is a circular flash which fits around the lens for macro photography. The ML-3 is compatible with TLL operation but is not compatible with E-TTL and so is not suitable for digital SLRs.

Canon Speedlite 480 EG

Bob Atkins

The 480EG is a handle type flash (“potato masher”) rather than show mount. It had coverage for a 35mm lens, but came with clip on panels for 20mm and 135mm coverage. It was Canon’s most powerful speedlite with a Guide number of 68 (M @ ISO 100) when used with the 135mm Tele panel. Normal operation was via a PC connection and exposure was automatic using an external sensor. However it could be connected to the hotshoe of the camera using a special cord and in that mode TTL operation was possible. the 480 EG is not compatible with digital SLRs as it has no E-TTL capability.

Which one to buy?

For most amateurs who aren’t interested in wireless multi-flash work, the 430EX II is probably the best buy. It’s a very good on camera (or off camera with the OC-E3) speedlite. It has manual control, a tilt and swivel head and is fully compatible with all Canon EOS bodies (film and digital).

If you are interested in multi-flash lighting using speedlites, then the 580EX II would be the one to get since it can act as a wireless controller for multiple slaves (420EX, 430EX, 430EX II, 550EX, 580EX or 580EX II). It’s also a good choice if you need fast recycling and a lot of flash capacity since it can be operated with an external power source.

The 220EX is a very basic flash. If you just want something small and light which can operate in a fully automatic mode, then it’s OK, but I’d certainly go for the 430EX II unless size and weight were critical.

Current Canon Hotshoe Mount Speedlite Specifications

More

• Photo.net Canon EOS discussion forum
• Canon DSLR System Overview
• Canon USA web site
• Factors to Consider when Choosing a Digital SLR