Canon EOS Accessories
Canon 550EX flash and TC-80N3 Remote Timer
by Karen Nakamura

Overview and Personal Comments

The Canon EOS system was designed from the ground up as an all-electronic camera system. Thus, the accessories it uses - from flashes to remote cable releases - all use proprietary connectors and transmission protocols. The good news is that they are much more advanced than their predecessors. Using the text or images on this website without permission on an ebay auction or any other site is a violation of federal law.

This page describes the E-TTL flash units (mainly the ST-E2, the 550EX and the newer 580EX) and then has a review of the Timer Remote Controller TC-80N3. The flashes can be used on all contemporary EOS cameras, while the TC-80N3 can only be used on certain high-end (semi-pro and professional) EOS cameras: 1v, 3, 10D, 20D, 1D variants, etc.

Canon E-TTL Flash System (EX flash units)

Ancient history: In the beginning, before you could control the output of your flash unit electronically, there was guide numbers. You would receive with your old bulb flashes a little card that would give you the "guide number" (GN) of your flash bulb. If the GN was 25 meters at ASA 100, you would divide that by the distance to the subject and use that as your aperture. So if your portrait subject was 3 meters away, you would use 25/3 = f/8.

Auto-thyristor: The key innovation in electronic flash units was when they gained a circuit that would measure the amount of light hitting the subject through a little round window on the front of the flash and quench the flash as soon as there was enough light received. These worked well -- assuming the flash was measuring the same amount of area that your lens was. If you were using a very wide angle or a long telephoto lens, the system didn't work as well. It also restricted you to certain lens apertures and didn't allow you to use filters.

TTL: So the next key innovation was Through-The-Lens (TTL) flash metering. Basically the auto-thyristor "sensor" was moved into the camera body and measured the flash strength from a reflection off the film surface (off-the-film [OTF] measuring). This meant that the flash system now could adjust for the lens aperture, focal length, and filters since it "saw" exactly what the lens saw. The disadvantage was each camera manufacturer implemented their own TTL signalling system. This meant you could not use a Nikon TTL flash on an Olympus body. The other disadvantage of the TTL system was that if the user selected an aperture that was too small, the TTL system would only be able to warn you that there wasn't enough light after the photo was taken. Not very friendly. The final nail in the coffin was that different film stocks have different reflectance values (try some different brands and see the difference!) so TTL was not accurate enough for critical slide film use.

A-TTL (Advanced-TTL): Canon improved on the TTL concept by pre-firing a small (1/20 strength) flash before the main flash. The pre-flash allowed for calculation of a wide enough aperture to allow flash photography. The actual flash strength is measured off the film (OTF), just like in standard TTL, so it's susceptible to changes in film reflectance. This is the system used on the Canon EZ series of flash units. I don't own any, so this is all I'll say on this subject.

E-TTL (Evaluative TTL): The A-TTL system wasn't perfect. The pre-flash only controlled the aperture pretty crudely. Evaluative TTL fires a pre-flash like A-TTL, but as the name implies it allows the entire metering system to evaluate the pre-flash with the camera's matrix metering. Based on the pre-flash, the camera determines the flash strength and optimal aperture. No measurements of flash strength are made off-the-film (OTF) which means that the E-TTL system is impervious to variations in film stock reflectance. The E-TTL system also allows for slave flashes to be used. The pre-flash includes communication with the slave flashes and also allows for "Flash Exposure Lock" (FEL). This allows you to pre-flash with the focus point selected on a medium-grey area of your subject in order to make sure the flash isn't fooled by overly white or dark subjects.

E-TTL II (Evaluative TTL-II): The Canon 1D Mk II, 1Ds Mk II, 20D, and some other cameras released in 2004 introduced the new E-TTL II system. Up to now, Canon did not use the lens distance to the subject (obtainable from the auto-focus system) in the flash calculations. This meant that the E-TTL system could be fooled by specular reflections (a mirror or glass window in the background) as well as very bright or dark subjects (notably a white wedding dress or black tuxedo). This is one of the reasons professional wedding photographers were drawn to the very sophisticated Nikon 3D RGB flash system which used both subject distance as well as subject color in its flash calculations. With E-TTL II, Canon now uses subject distance but it still has not caught up to Nikon in using subject color.

Professional Flash Units: The 550EX with E-TTL was the mainstay of the Canon professional flash line for half a decade. In late 2004, Canon released the successor model, the 580EX. It features the new E-TTL II system, better compatibility with the latest digital SLRs, and was smaller and recycled faster. There's no reason not get one.

ST-E2 Speedlite Transmitter: The E-TTL system allowed for remote flash communication. Professional portrait photographers have always used more than one flash unit in order to balance the direction and amount of light falling on their subjects. E-TTL allowed for three groups of flashes (each group containing an unlimited number of flashes) operating on 4 different channels. This is an optical system, not wireless, so the distance is limited. You can control the amount of light coming from each group. The 550/580EX units can operate as master flash units (or slaves) and are the most flexible way of controlling the system, but you can also use the small ST-E2 transmitter as a master controller as well. I use the ST-E2 myself - but mostly for macro photography - as I don't use flash much in the field and I don't do much studio photography.

Canon EOS System Compatible Flashes (professional models)

Timer Remote Controller TC-80N3

With the EOS line came the end of mechanical remote cable releases. Unlike Nikon which has a mechanical cable release socket in all of its professional series cameras (even the digital ones), Canon moved to an entirely electronic system with the EOS line. This in itself wasn't a bad move.

Electronic releases have many advantages: the length is only limited by the amount of extension cable you have attached; you can electronically transmit the signal to focus the camera as well as release the shutter; and it is easier to build electronic cable releases with sophisticated timer circuitry or remote control releases than it is for mechanical ones.

But the main disadvantage is proprietary connectors. And Canon doesn't win any prizes here. The first EOS cameras used a T3 type connector with a screw-in mount. The consumer EOS line then moved to a 1/8" headphone jack style connector. Then the professional EOS line shifted to the new bayonet-style N3 connector. For people making their own remote releases, it's easy to mcguyver your own headphone jack connector, but if you want to make an N3 remote release, you have to cannibalize an expensive Canon cable.

Enough with the critique. I came to praise the TC-80N3 and not bury it. I am in love with this little remote release unit for the professional EOS line (N3 connector cameras: 1v, 3, 10D, 20D, 1D series, etc.). It costs an arm and a leg ($133 from B&H) and many will decide to get the cheaper RS-80N3 ($50) which doesn't have any timer circuitry.

The TC's advantage is that it's more than just a timer. It has three timers (and one counter) in it, each which can be set independently or in combination. Each timer can be set from 1 second to 99 hours 59 minutes 59 seconds with second precision.

• SELF: This is the initial count-down timer. Set this to '4' for example and the TC will wait 4 seconds before releasing the shutter (and then move to the next timer interval if applicable)
• INTERVAL: This is the amount of time the TC will wait in between shutter releases. Set this to 10 minutes, for example, and the TC will start taking photographs at 10 minute intervals.
• LONG: This determines how long the TC will hold down the shutter button. If you set your camera to Bulb, you can direct the TC to take photographs up to 99 hours long - although your EOS camera will run out of batteries well before this expires.
  There's also a hidden feature. If you set your EOS camera to automatic exposure bracketing, but also turn on the motor-drive to take multiple photographs, then the EOS camera will only take 3 photographs even if you hold down the shutter button continously. So if you set LONG to 30 seconds, then the camera will take three 0/-/+ photographs each interval.
• FRAMES: This allows you to set a limit to how many frames (in total) the TC will take. So if you set INTERVAL to 1 hour and FRAMES to 6, then your camera will take 6 photographs in the next 6 hours and then shut-off. There is a limit of 99 frames.

The power is that you can combine all of these timers:

• SELF=10 seconds; INTERVAL=2 minute; FRAMES=90. The camera will wait 10 seconds (I do this to allow it to "settle" from vibrations imposed by me tramping around it) then take a frame every 2 minutes for the next three hours. You can use this to take "flower opening" type sequences.
• INTERVAL=15 minutes; LONG=1 minutes; FRAMES=12. On the camera: AEB=2 EV, Exposure compensation=+2. You can use this in astrophotography to take a series of 3 photographs (+0, +2EV, +4EV) every 15 minutes for 3 hours. You might do this to track a comet or satellite across the field. I did this with the photograph above.

Other suggestions welcome!

About Canon

Canon started out its life as Seiki Kohgaku Kenkyuujo (Precision Optical Research Company). Its first goal was to produce domestic inexpensive Leica clones, and it released the Kwanon, its first camera in 1934. Interestingly, they used Nikon lenses since Nikon was already established as an optical lens manufacturer and was not making any of its own camera bodies at that time. Canon soon gained the ability to make their own lenses and never looked back. Nikon also went on to produce some reasonably popular cameras of its own as well.

The name 'Canon' comes from the Buddhist deity Kwanon and early Canon cameras were actually spelled 'Kwanon' and the lenses were named 'Kyasapa' after another deity.

Side note: Canon is my favorite Japanese company along with Honda. I actually interned for Canon Japan (ok, Canon Sales Japan, a part of the Canon keiretsu) during a summer in college and loved my coworkers to death. They keep coming out with innovations that take your breath away.

On the Net

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