Bracketing With Flash For Exposure Fusion and HDR – Revisited

January 27th, 2014

EFplusflashI think it is time to revisit the subject of the hybrid flash/bracketing. I’ve talked to people recently that seemed offended when I pointed out that adding a single manual flash to their bracket shooting could improve the quality of their results. We’ve talked about this several times on the blog since the summer of 2010 and in the flickr discussion group. I think there are some folks that missed out on that discussion. Iran Watson uses a variant of this technique and did a post about the way he uses it in April of 2011. But let’s start from the top. The first question is why? What’s the point of using flash when you are shooting brackets? You thought the reason you shot bracketed exposures was so you didn’t have to use flash, right. Well the fact is that when you use HDR or EF for interiors you tend to get low contrast results (more so with HDR than EF). That is, the blacks are not as black as you’d like and the whites are not as bright and crisp as you’d like. The term that comes to mind is muddy colors and dirty whites. You also have issues with white balance. It turns out that if you add a kiss of fill light from a single flash makes these problems much better. If you add a little fill flash to your brackets you don’t have to spend as much time and effort in postprocessing to get rid of the muddy colors, dirty whites and wacky color balance.

Also, adding a touch of fill flash to bracketed shots can be done without having to “climb to the top of the learning curve” for full blown multi-off camera flash technique. There is a discussion in the PFRE HDR & Blending discussion group on this subject. I’ve been doing some experimentation with this technique so here’s my summary of how to bracket with flash:

  1. Setup your bracketing as normal (on a tripod, aperture priority and exposure bracketing -2,0,+2) except add a manual off camera flash. For the shot above I used a Nikon SB-80dx triggered by a Cactus V2 Wireless flash trigger. The transmitter end of the Cactus trigger was in the hot shoe of my Canon 5D MkII with it’s trigger cord plugged into the 5D’s PC connector. The SB-80dx had a Cactus receiver connected to it.
  2. Set the drive mode to single shot so that you have to release the shutter for each of the three bracket shots. This is to make sure that the flash has time to recycle between each bracket shot.
  3. Use a remote shutter release so you don’t have to touch the camera body. I used the Canon TC-80N3 although you could probably get by just touching the shutter release button if you are careful and your tripod is sturdy.
  4. Aim the flash either towards the ceiling, a blank wall or the joint between the ceiling and the wall so that the light from the flash creates a large, soft fill light. On my example above I had the SB-80dx sitting on the top of a media cabinet, camera right, pointing at the ceiling. The ceiling is diffusing the light out in all directions so their aren’t many shadows.
  5. Adjust the power on the flash manually (some where between 1/8 and 1/1 – same power for all three bracketed shots) so that you get a good set of 3 histograms (you want the histograms high but not clipped histograms together to fill up the available histogram space. -2 will be left, 0 will be center and +2 will be right). See Dan Achatz’s description in the PFRE HDR & Blending discussion group.

To summarize: this technique adds the same constant level of fill flash with a single flash, to each of the three brackets you shot. This fill flash is improving the quality of the light so that the whites are whiter and the blacks are blacker. This same technique works similarly with either brackets used for HDR processing or brackets processed as Exposure Fusion (EF). For those that are already shooting brackets with flash I’m sure you’ll be able to add refinements or variations to this technique.

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14 Responses to “Bracketing With Flash For Exposure Fusion and HDR – Revisited”

  • A great summary. All marketing images are about light and how we draw the viewer into the image; this can include using shadows. HDR is a simple software tool that does need added light to define shapes and colors within a shot. Without light, you will have a muddy image that lacks definition. Larry – great summary.

    For me I have always worked to minimize spending time in a software program and get the final shot right the first time…and that means using a light meter and appropriate gels. I may not be the fastest in getting in and out of a shoot, but I know my results are consistent and sharp when I leave a property. The above article is a really good summary of basics.

    The rest is what you choose to do within your mind to create your style.

  • My Nikon allows me to bracket the flash AND the exposure so I always include a flashed set as well as a set of ambient brackets. The ambient brackets rarely look as good as the flashed set but they are great to use as a layer to remove accidental shadows, hot spots and reflections. That way I don’t have to obsess over getting rid of them (accidental shadows, hot spots and reflections) at the time of the shoot and I can get out of the property faster. The flashed set also gives me great window pull. I use Oloneo Photoengine for my fusion then import to Lightroom and export to PS for layering and masking. It’s not as time-consuming as it sounds.

  • Its great to have this kind of articles because we can learn from others in order to go to improve the work, so , thanks you a lot.

    I dont have clear the success because if do you take HDR you keep the ambiance lights and shadows, if you lit with flash so you are fighting newly with new and artificial shadows, and more visible if do you use a single flash, so flash shadows will modify the final HDR image adding odd shadows and more if the pop of flash is stronger than ambiance light to correct colorcast.

    I would like to practice this tech when i have clear how to develop it.

  • Greg, not true. In fact I’ve found that blending (I do primarily exposure fusion) and bouncing flash on the three or so bracketed shots, tends to smooth out the shadows. Direct flash will always be a problem, which is why I say to bounce the flash. Adding flash cleans up color casts to a large degree and produces a much more pleasing blended photo.

  • Through my experience, I would learn this technique so you have another tool in the toolkit, and to not rely on it 100% I only do this when the room is too big or difficult to get even lighting throughout, and other rooms (like the one shown in the example) are far easier and quicker to use the single exposure/flash fill method. There is nothing easier in post then when you are dealing with single exposure images that come out of the camera properly exposed.
    Also, I have found that you don’t need as many brackets to get a good blend as some people think. Routinely I see people using 9 brackets, which will only eat up way more time in post. I have found that no more than four are really needed to get a nice blend. Many times I only need three- one for the window pull, one for the shadows and one in between.

  • Using this technique, when you set the flash level, do you set it so it has good balance with the ambient light in the middle exposure or in the brightest exposure?

  • @Shawn – as with any use of manual flash a little trial an error is necessary… it doesn’t take long to get a feel for what works best for you.

  • @Jim

    Regarding the number of brackets, I have found (rather un-scientifically) that you’ll get a better image doing, say, 5 exposures at 1 stop gaps vs 3 exposures at 2 stops gaps. You cover the same dynamic range, but for whatever reason the resulting image is better when using more frames within that range.

    With that said, the differences tend to be minor: less noise in the shadows, very slightly richer colors in the highlights. I don’t know if this phenomenon has a physics explanation or if it’s simply the way in which exposure fusion software interprets the data, but it’s good to know in case you ever need to print one of those images.

    I don’t bracket often, but when I do I’ll always over-bracket. It doesn’t take up much space, and then I can pick & choose what frames I want when fusing.

  • @Jeff,
    I agree that more data in post is better. The more points on a graph, the smoother the curve. My most difficult shots used to be all white kitchens and living areas with black or very dark furniture. When I started doing +-3 at 1 stop gaps, I’m much happier. As for including one or more flash shots, I’m interested but have zero equipment to experiment with. How can I start with on camera flash without fiddling with the camera too much? I’m using a Canon 70D that lets me take the above seven exposures with one press of the shutter.

  • Mike Martin, I have a 70D but it will only do 3 exposures. How did you expand that to 7?

  • @Robert, abt the Canon 70D:
    You can change the default 3 exposures to as many as 7 shots in the Custom Functions Settings. Specifically C.Fn 1-5: Number of bracketed shots.
    This info is not included in the little manual that comes with the camera. Its in the expanded manual available on-line.
    “The number of shots taken with AEB and white balance bracketing can be changed from the usual 3 shots to 2, 5, or 7 shots”.
    Once changed, it remains that way even after the camera is turned on/off (good). However, you must remember to turn on AEB every time you turn on the camera (using the “camera” 3 tab). Then use the dial near the shutter button to select the exposure range. I normally set it to +-3. However, the camera can be set at, I think, to as much as +- 8. The ability to take as many as 7 exposures with one press of the shutter is the major reason I upgraded. The 70D will also do “in camera” HDR two ways using only 3 exposures. Thanks for asking.

  • My thing is, if you’re taking the time to use flash and set it up in a way that illuminates the scene pleasantly, why not nail it in 1 shot and save yourself the extra work?

  • @Robert – You are correct, if you know how to use small flashes, you get a better result by using flash, but in larger rooms it may take 2 or 3 or 4 small flashes to get the job done. And there is definitely a learning curve to learn how to use multiple flashes effectively. The fact is many folks are more comfortable shooting brackets and a single flash used the same way every time can save a huge amount of time in post.

  • I have produced a nice result by doing a 9-stop EF and also a separate off-camera flash exposure. Then layer the flash exposure over the finished EF in Photoshop at about 40-60% opacity.

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