EOS Speedlites

EOS Speedlites are a small flash unit manufactured by Canon for use with their cameras.  

The speedlites are useful due to their portability, low cost, battery power, wireless abilities, and their ETTL II system.  These same strengths are also part of their weaknesses which will be addressed towards the end.

Speedlites are also great because they help increase focusing accuracy, especially in low light situations. They have built in red LED lights that shine on your subject and then focus the camera tack sharp.

Currently Canon sells 3 flash models, 230, 430 and 580 Speedlites. 
This guide will focus only on the 430 and 580 speedlites.
The 230 is a fixed position flash that is not very powerful, therefore I would not recomend getting one.

XSi and 580ex II

The 580EX II and 430EXII are great flashes, they provide customization and manual control that allows you to dial in proper exposure and lighting techniques.  You can also control them through your XSi’s lcd menu.

The flashes feature the ETTL II system, this basically works in combination with your cameras metering system to achieve proper subject flash exposure.   What does that mean?   here is my best attempt to explain how ETTL II works.

first, ETTL ?   evaluative – through the lens     metering.  
Your camera has a metering system, it meters for the ambient light of your environment, there are a few metering modes – but none the less it meters in some fashion.  The camera meters the scene and helps achieve the best shutter / aperture composition to properly expose an environment or subject ( based on metering mode). 

The addition of a flash, does not cause the camera to adjust its exposure preferences.  The camera will evaluate and meter independently of whether or not a flash is used or not used.  When the shutter is pressed, the flash will fire a pre-flash which instantly sends a reading to the camera.  The camera then via its speedy processor will compare the cameras metering vs the flash’s pre-fire and the flash will then take that comparison and estimate where the subject is. 

How does it do that?  well when a flash fires, it brightens those things closest to it, the flash then estimates that the intended subject matter is being lit up by the flash and adjusts the intensity of the flash so that the subject isn’t over exposed by the flash.   say what??   its definitely some what confusing, but the bottom line is the flash sends out light and then in a fraction of a second calculates what it believes to be the appropriate amount of flash to light up the assumed intended subject. 

When the flash is facing directly down and at the scene, the flash will also calculate the distance to the subject and know the type of lens being used to  either “zoom” or “wide angle” the flash.  The flash when zoomed in will have a very directed and pointed light, and when zoomed out, will have a wide light that is soft and even throughout the scene. 

back of 580ex II on XSi

ETTL is a great system, it works pretty well and can assist in obtaining much better shots.
When in AV/TV mode your camera and flash act as if the flash is there as fill light only.  How? Well the camera will adjust to properly expose for ambient light. Your flash will then fire, in addition to the ambient exposure.

When in manual mode, the flash will have the ability to be the primary light. How? You select the aperture you want… you then put in a shutter speed of 1/100 – 1/200 whatever you want. Now assuming you are indoors, the flash will be the primary light.

When you first start using your camera with a speedlite, go into the flash controls on the camera menu and turn the flash synch from “fixed 1/200″ to “auto” this will remove any in ability of your flash to shoot at varying speeds over or under 1/200 of a second. This is an important step, as its not heavily advertised. If you are shooting at 1/200 or higher you will need to enable the “High Speed Synch Mode” of your flash. This is a lightning bolt button on the back of the flash.

When you being shooting, get comfortable with your flash, leave it in auto ETTL mode and try shooting in both manual and aperture priority.

When shooting ambient light, aperture and shutter speed factor into the amount of light let in to your image. When shooting with an additional flash, there is a second exposure occuring. Flash is not controlled by shutter speed, it is instead controlled by the aperture of your lens. The wider the aperture, the more light from the instant light of the flash will be recorded. The smaller the aperture, the less flash. This is an important understanding to distinguish. Aperture = controls ambient light and flash, shutter speed = ambient light control only.

If you take a shot with a flash, and you believe the shot has too much of the artificial flash lighting, there are two ways to reduce the flash. One is to lower the aperture width, if the flash is in manual mode and you leave it with the same settings the light from the flash will not be as apparent. You can also adjust the flash by lower the flash exposure compensation on your camera. This is an easy method when using the flash in auto mode.

More Advanced Speedlite uses:
Eventually you may realize that you would prefer to have more predictable outputs from your speedlite flash. This will entail switching your flash from ETTL mode to Manual mode. Now you can control the output of your flash in F stops just like selecting a shutter speed or aperture.

When I shoot in manual mode, I select a shutter speed of 1/180th of a second, an aperture of 5.6 to 8.0 and I start off by firing my manual speedlite at 1/4th power with the wide angle panel out and in use.

From there, I will either adjust my ISO or adjust the flash output to a higher or lower amount in order to achieve the shot I desire. It may sound hard, but after about 15 minutes of playing around you’ll really start to get the hang of it.