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Why You Can’t Use Auto Exposure Bracketing When Using a Flash

July 11th, 2017

Ron in Northern California says:

I love your resource here. I have a Canon 5D MKIII with 600EX-RT speedlite and ST-E3-RT trigger. I’ve been shooting for a couple of months using brackets and Lightroom HDR. I had some color consistency issues and after reading some your posts on using a manual flash I added flash to my bracketing and it really helped! Unfortunately, I discovered in the process that my wonderful Canon equipment doesn’t support AEB with flash. Not even with the flash set to Manual. Is there a reasonably priced manual trigger that will support the automatic exposure bracketing?

I doubt that you’ll be able to get any flash or trigger to work with auto exposure bracketing (AEB). The reason AEB doesn’t work with flash is that the AEB function doesn’t have a way of waiting for the flash to recycle. But there’s a very simple solution for this problem that will allow you to use your current flash gear as described in this post.

This bracketing technique is manual. That is you are changing the shutter speed manually and pressing the shutter manually for each bracket so while you are bracketing just make sure the flash recycles each time before you press the shutter.

Notice that this technique is also making sure that you are capturing the full brightness range of the space. That is if you follow this technique when the room is very bright you may be taking more brackets than if the room has a smaller brightness range.

Update 7/12: I was wrong, there are flashes that will work with AEB! See comments for details.

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5 Responses to “Why You Can’t Use Auto Exposure Bracketing When Using a Flash”

  • I also use the Canon 5D MkIII and ran into the same issue and found what “appeared” to be a dead end. Being a stubborn Swede though, I did not give up. I will spare all with the wasted time and money and go straight to the solution. I purchased a Godox AD200 Pocket Flash (actually a few of them). It’s close to half the price of the Canon 600EX-RT with more power, super fast recycling and outstanding battery life. On my MkIII i use the Godox XT32C controller. Both the flash and the controller are set on manual. Now here is the trick or work-around. When you mount the controller on the camera, take out one of your business cards, cut it the width of the flash shoe on the MkIII. Slide it just far enough in to cover the four small connection points, leaving only the center pin to make contact. This is the pin that carries the signal to make the flash work. With the other pins not making contact the camera doesn’t know to limit your lower end shutter speed.

    Now for the cool part. Set your camera to shoot in Auto Exposure (Av) and set it to do a seven shot bracket. Set the spacing of the brackets at 1 2/3 between each shot. Set your focus on manual and your motor drive for single exposure release. You now frame up your shot as you would normally do, point your flash at the ceiling or other area for bounce, set your manual flash exposure to something like 1/4 power and press the shutter release seven times. The camera will set the exposure based on the ambient light level and provide the exposure bracketing. The flash will fire for each shot regardless of the shutter speed the camera has selected. My typical shutter speed will range from 1/30 of a second to 30 seconds for the seven exposures. So you CAN use auto exposure bracketing with a flash. I use this technique every day and it works and works well.

    As a side note, the Godox flash recycles so fast that I will on occasion, forget to take my camera off multiple shutter release from shooting exterior images. If I am at a maximum of 1/4 flash power, the flash will keep up with the rapid fire of the shutter. Do yourself a favor and program the camera settings into one of the custom settings so you can just set the camera to C1 when you do your interiors and you are all set in seconds. Also, I did graduate from the cut up business card and purchased a hot shoe connector that had internal wiring. All of the wires except the center pin were cut and it works like the business card approach but more professional. There is a bit more to all of this, like adjusting ISO for various lighting conditions, different flash modifiers, etc. but using the above, Auto Exposure Bracketing with Flash will work.

  • The Godox XT16 mounted in the hot shoe will allow AEB with Canon cameras. You can adjust the flash power with the XT16, but cannot do HSS.

  • Surely if you’re using a Canon then you just set your AEB to your desired sequence and use single shooting mode, so the flash has time to recycle.

  • If youre taking a lot of shots its can take quite some time to set each one up manual I ‘curlyed’ my Nikon by setting it to auto bracket ann then fire it in interval timer mode, works like a dream. But you need to see if you have interval timer mode. It takes my 5 shot bracket with flash in 10 seconds (I give it 2 seconds between shots for the flash to recycle)

  • I shoot with a Canon 5DMII with a hot shoe mounted Canon 580EX flash unit. I have loaded MagicLantern onto the memory card and when the camera powers up, MagicLantern is loaded which adds many, many features not enabled by Canon.

    MagicLantern will use the Camera’s auto exposure system and take as many brackets as necessary to capture the full range. I manually turn the flash on prior to tripping the shutter and then let it fire away from 1-3 exposures depending on the room, close walls, high ceilings. The flash is usually dialed back to -3.

    Once the shutter is tripped, no adjustments are necessary again on the camera. The only manual part is turning off the flash after I am satisfied I captured enough frames with flash.

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