HDR Photography (an introduction)

By Christopher Rainville
HDR photography, or High Dynamic Range photography, has become quite popular in recent time.  By definition, HDR photography is combining different exposure values to one finished photograph. To understand why we do HDR photography it’s important to know how your camera works and more importantly, how it compares to the human eye. Your camera most likely sees around 5 to 6 f-stops. Your eye has a wider dynamic range and can see the equivalent of 11 or 12 f-stops of light. What this means is, where you can see details in shadows and color in highlights your camera cannot. The purpose of HDR is to expand the dynamic range of the photograph. The dynamic range is the total exposure value of light that your camera can see. By shooting multiple exposures the dynamic range is expanded because the total value of light is stretched through the entire scene. For example, on an underexposed photo definitions are more visible in clouds and in areas where the sun is reflecting off of white objects. In an overexposed photo, details like the interior of a building through an open door, are visible. By combining images with different exposure values we can include details in the highlighted areas, and details in dark shadows.

HDR combines multiple exposures to increase the dynamic range of a photograph.

Now that you understand what HDR photography is, let’s explore how it is created. The first process is deciding on a subject. Good subject matter is important to the success of an HDR photo. Typically, outdoor scenes with dramatic skies featuring lots of clouds work well. High contrast photos with a lot of texture also work best for high dynamic range photography. You also want to try to choose scenes or subjects that are not moving. Since HDR is combining multiple exposures moving objects can appear “ghosted” or blurred in the final photo, but more on that later. Typically, HDR is not for portrait photography but I have seen it done with great results. Another thing to look out for when choosing a subject for HDR photography is avoiding noise. By noise I mean the amount of grain in the photo itself. When shooting a darker scene with high ISO for example, you might get enough noise in each of the exposures that when processing them the noise becomes amplified. This creates a grungy effect to the photograph. This grungy effect can be quite desirable depending on the subject matter but in most cases it is better to make a clean HDR photo grungy than to try to clean a grungy HDR photo. For HDR photography you will need at least three exposures. One at low exposure another at what would be considered “proper” exposure, and another at high exposure. Before we go any further we should probably talk about equipment. A lot of photographers use five exposures but three is the minimum.  Typically not all cameras can perform HDR because they don’t allow manual exposure settings. Some cameras can mimic HDR in the camera or can combine multiple exposures to produce an HDR image as a single outputted image. The Casio EX-ZR 100 can produce an in camera HDR photo as well as the more stylish over processed HDR photo. Not all camera manufacturers that have built-in HDR capabilities call it HDR, so be sure to check your manual to see if your camera has that capability.  Fujifilm calls their built-in HDR program Advanced Pro Low-Light Mode.  A little searching at manufacturer’s websites can give you more information on each manufacturer’s definition of this feature. My main concern with an in camera HDR is that you’re allowing the manufacturer to determine the final result. Anything that is automatic usually means compromise. For the purpose of this article I want to explain the basics of HDR photography using a camera that allows you to make those decisions  yourself by setting your own exposure values, and post-processing decisions. You’re going to want to set your camera up to take bracketed photos. Bracketing is a pretty common feature on most digital SRL’s and allows you to take photos with different exposure values without stopping to readjust the camera manually. On my Nikon D90 I simply turn on the bracketing feature and it allows me to  adjust the steps in between each photo. I typically set mine between one and two f-stops in between photos, usually never as low as one but never as high as two. On my camera, I can set it up in burst mode and it will fire off all three photos quickly with the different exposure values however I can also push the shutter button for each exposure change. Once again, check your user manual to determine how to take bracketed photos.

Books and websites about HDR photography will often state that you need a tripod. Although using a tripod is an ideal method of taking your photos, carrying around a tripod in Walt Disney World is not always practical. Needing a tripod has a lot to do with setting up your camera. Idealistically, you want to take all of your photographs at the same f-stop for a consistent and even depth of field focus. For the sake of continuity, as you take your separate exposures you would want to adjust your shutter speed and not your aperture. If you’re not familiar with aperture and its relationship to depth of field let me give you a brief explanation. Basically has your aperture size increase the area that stays in focus decreases. So how does this affect your multiple exposures? Let’s say your subject is Cinderella Castle shot just before The Liberty Sq., Bridge. So the shot would include the moat and the Castle as well as a fair amount of sky. If you were to use a dramatically different aperture setting for each one of your photographs you run the risk of having areas of each exposure not in focus. This would essentially ruin the final HDR photograph. So to get your highest exposure you need to keep the shutter speed open longer this is why a tripod is recommended. If your shutter speed drops too low, you would not be able to keep the camera steady enough to avoid blur caused by camera shake. The little-known secret about creating a shallow depth of field with a wide aperture is that the phenomenon depends on the size of the camera sensor. The larger the cameras sensor is and its focal length (distance from focal point to sensor plane) for more susceptible a shallow depth of field becomes a problem. This is why small point-and-shoot cameras often have little or no depth of field regardless of the aperture setting. The same is true for crop sensor DSLRs. On my D90 which is a crop sensor camera, only my fastest lenses can create a noticeable shallow depth of field. On my camera, depth of field is affected more by focal length than aperture size. What I do to avoid using a tripod is to break the aperture rule. Instead of using shutter speed to adjust my exposures, I allow the camera to select aperture and ISO.  This allows me to shoot handheld without the use of a tripod for most outdoor daytime shooting. Of course this comes with some trade-offs. I do run the risk of changing the depth of field, and in areas where it gets a little dark the higher ISO can introduce some noise. I do this by shooting in shutter priority mode essentially locking my shutter speed.  I try to use a fairly slow speed so that the aperture doesn’t have to open a lot and the ISO won’t rise too high. This is usually somewhere around 1/100.  I have had some depth of field issues with this process but it seems to work 99% of the time.  Again, if my focal length is long, it will exaggerate the shallow depth of field.

When you get your camera set to take your bracketed photos it’s time to think about positioning the camera. This is another reason why a tripod is often considered essential. Remember, the point of the three exposures is to line them up for your final outputted photograph.

There was a time when I first started doing HDR that all 3 photos had to be pretty much dead on for them to line up correctly and avoid blurry or “ghosted” images. But as the years passed and new versions of software have been developed this is becoming far less critical. Once you hit that shutter button and you take your 3 bracketed photos unless you really move around they should all line up pretty good and the processing software should have no trouble matching them up. If you’re looking to take additional exposure shots and have pulled the camera away from your face to make adjustments remember to do this little trick. I typically pick a point in the subject through the viewfinder and lineup one of the crosshairs to a specific point, that way when I lift the camera back up and look through the viewfinder, I know where to position the camera. I find this technique works very well. I usually will use the corner of a window or door way, anything that is easy to line up again. I will tell you that if you use this method you will have some cropping of the photo. If you use a tripod, photos will automatically be lined up and no auto cropping will occur when you process the exposures down to one photo. The one thing you must remember whether your using a tripod or not, is to not change your focal distance. It’s very frustrating to get your exposures into the computer and find out that they don’t line up because you change the focal length.  Another thing to consider doing is to lock your autofocus. Autofocus can become a problem if you’re shooting in an area where it can easily lock on a different object in your composition. Let’s say for example you’re doing a 3 exposure piece. If you have a very sensitive autofocus in your camera it may switch focus points during each exposure. I very rarely run into this issue but when it does it can ruin a good HDR photo. Sometimes the focus is so minor that I don’t notice it on the small LED screen on the back of the camera, but once you get it on a monitor it doesn’t look so good.

When you captured at least 3 exposures it’s time for the post processing work.  HDR processing can be done in Photoshop CS4, CS5, and CS6. Photoshop does a lot of things really well however HDR is not one of them. This is not to mean that Photoshop won’t be used in the process but the bulk of the work should be done by software specifically designed to do HDR photography.  My workflow includes some touch up in Photoshop or Lightroom then exported directly to my processing software and then back into Photoshop or Lightroom for more enhancements.  If you only have Photoshop the process for HDR you can use it however you will find CS5 more robust and easier to use then CS4 and updates in CS6 are better but still not great.  The software I use to produce my HDR photographs is called Photomatix Pro by HDRsoft.  I highly recommend this software and it sells for around 100 bucks for the Pro version and about $40 for the essentials version.  There are also other plug-ins for Aperture and Lightroom for $79. If you have an older version of Photoshop and would like to use it, Photomatix offers a 32-bit version of their “tone mapping ” plug-in for Photoshop CS2, 3, 4, and 5. Tone mapping is the primary adjustments made to HDR photography.  Another good choice for HDR software would be from Nik software called HDR Efex Pro which is also just under $100.  If you wish to skip the process altogether but still want the look of an HDR, Topaz Labs offers a program called Topaz Adjust.  It’s around $50 and is an HDR photo emulator.  I find Topaz lab plug-ins to be an extremely good value offering a lot for very little money compared to other plug-ins.

To cook or not to cook your HDR, that is the question. Believe it or not there is a huge controversy in the world the photography on whether or not to over process your HDR photos. Commonly referred to as “cooked”, these photos dramatically increase the sharpness, vibrance and color saturation, as well as midtone contrast.  Other cooked HDR photographs will actually desaturate the photo slightly and use some hue adjustment values to create some pretty awesome effects.  If you frequently visit photography blogs you will find some pretty hateful postings about HDR photography. I’m not really sure why this is, but the same could be said for a lot of stylized photos. Personally, if you have seen my HDR photos you will notice I am a huge fan of overcooked HDR photography.  I personally like the way it looks more like a painted illustration then a photograph. Some of the tonal values have been compressed and the sharpness and vibrance gives harsh edges an artistic appearance.  That’s not to say all of my HDR photography is overcooked. I often post photos on Facebook.com/wdwphotoclub that look like a standard photograph. Another common HDR look is the “grunge” look. Typically, areas with a lot of digital noise are amplified and often have a flattened non-contrasting appearance or a heavy contrasting and gritty dramatic appearance. This look is also popular when processing edgy portraits like those used for athletes and musicians.
Hopefully you have found his introduction to HDR photography helpful but if you would like to see more examples of great HDR photography I recommend Ben Wilmore’s web site. I started doing HDR photography after attending a workshop of his a few years ago. Ben is an amazing photographer who not only produces fantastic HDR photography, but also is a light painting photographer.  Light painting is a process of using artificial floods and flash lights to create sometimes fun or dramatic nighttime photographs. Also check out Rick Sammon’s blog for more great examples.
Walt Disney World offers a lot of great HDR subject matter.  Dark interior spaces like the resort lobbyies also look great in HDR.  Take the time to look at the software available and see if you can download a demo and shoot some stuff in your own backyard.  Once you get to know it and practice it you will be able to add a new dimension to your photography.  I look forward to seeing some of your work posted on the WDW Photo Club Facebook page.

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