EOS Flashes

Canon EOS Flashes

Fill-in Flash and the Shutter Speed

Canon, like all other camera manufacturers, has a flash mode to balance the flash with the ambient light, aka the fill-in flash. You need to have the flash in eTTL and the camera in Av mode. When using the flash, the aperture controls the power of the flash and the shutter speed controls the ambient light.

Canon: Setting Flash Exposure Compensation

In the Canon system, you can set the Flash Exposure Compensation (FEC) either on the back of the Speedlite flash or in the camera menu system. And they can be active at the same time.

And that's where the problems start. To avoid confusion, you should use one or the other place to set the flash exposure compensation not both. Why not both? Because the effect depends on the order that the flash exposure compensation was set.

  • If the flash exposure compensation is first set on the flash, then you can't set it in the camera.
  • If the flash exposure compensation is first set on the camera, and then you also set it on the flash, the flash setting will override the flash exposure compensation set on the camera.

Canon E-TTL II flash settings

Flash can be very complicated or fairly simple depending on how you set it up. Some people are masters, like Joe McNally of the Hot Shoe Diaries' fame and Syl Arena of the Speedlighter's Handbook fame. Some people are more on the child-like side, like me. There are two main problems:

  1. People want one easy solution that fits all.
  2. The camera/flash combinations are so sophisticated that they are using auto on the camera and auto on the flash.

The Secret Sauce

Lately there has been some controversy about the 10 steps to become a professional photographer… Life is getting more complicated because in the “good old days” it used to be “only” 7 steps. Why 10 vs 7? I don't know. But let's go back to the secret sauce.

Q: How do can you become a successful professional photographer?

A: Spend 20 minutes in your bathroom!

No, it's not what you think! Go to the bathroom and make photos to try to resolve your photo problems, from portraits to landscapes… But do it in your bathroom!

Why in the bathroom?

Canon: Bouncing Flash

The camera pop-up flashes and the “lower end“ flashes can only illuminate in front. Most “good” flashes allow you to bounce the light instead of just sending it straight in front. You can bounce the light to the ceiling or even behind you toward a corner or a large reflector.

Regular hot shoe flashes have only one power setting: the full power. To throw less light, they cannot reduce the power, they reduce the time of the flash. A ½ power is just the same amount of energy but over ½ of the time. A ¼ power is just the same amount of energy but over ¼ of the time... just like a camera shutter.

Camera manufacturers have spent millions upon millions to simplify the flash and make it work with bounce, slave, remote... Take advantage of it.

My standard settings for the flash operations for the camera (I even have it stored as C1) are:


What is EC? What is FEC? It's alphabet soup that stands for Exposure Compensation and Flash Exposure Compensation. This is used to differentiate what photographers do on the camera vs what photographers do on the flash. The Nikon world is completely different from the Canon world.

In the Nikon world, the formula is: EC + FEC = Total Exposure Compensation. An Exposure compensation of -2 on the camera and a Flash Exposure Compensation of +2 = -2 + 2 = 0, no exposure compensation.

In the Canon world, it's much more interesting.

How Many Flash Shots Before Shutting Down

Like most speedlight flashes, the Canon Speedlite's heads are hermetically sealed. “Hermetically sealed” means that no air can go in or go out. When things are hermetically sealed, things tend to heat with use.

The rumor is that “you can't do too many flashes or the speedlight flash will shut down for 10 to 20 minutes while the flash tube cools down.”

Yes, too many flashes will shutdown the speedlight flash to give it time to cool down. The question is: “How many is too many flashes?”

Flash: Fired but Severly Underexposed. Why?

The other evening, I took this photo:

Flash didn't fire properly

The flash didn't fire properly

The photo is taken f/5.6 1/80s ISO 800 with the flash. I didn't have an external flash with me and just wanted to add some light, f/2.8 1/40s and ISO 1600 or 3200 would have been good enough.

There are 2 exposures:

  • The ambient light, it's enough to give the feeling of the area/background.

Canon: 7D: Flash Exposure Lock

Canon 580 EX II flash/speedlight

Canon has this wonderful thing for flash, it's the E-TTL II system. With E-TTL II, you can control the exposure and the flash exposure separately. Basically, it sends a pre-flash to read the exposure across the 63 metering zones for what's dark (interpreted as background) and what's bright (interpreted as foreground). The problem is that I was looking to set the exposure and to lock that flash exposure for the rest of the photos.

The problem is where is the Flash Exposure Lock (FE Lock) button? I can't see it on the flash. I can't see it in the Canon 7D's menu. And of course, I didn't have any of the manuals with me.

Is My Flash Strong Enough?

Do you remember when you were in high school? When I was in high school, we had to study physics. We had to study light, waves… For the people that either didn't have to study physics or have forgotten it:

The light coming from a flash bounces like billiard balls. This means that light that bounces against a reflecting surface will bounce back with the same angle, i.e.

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