HDR Photography: What is High Dynamic Range?

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Have you ever seen a fantastic photograph of a natural wonder or a famous building that have incredible detail in the bright areas like the sky as well as in the shadows and darker areas and wondered why the photographs you take never quite seem to have as much detail or why you can get great exposure in the highlights and the sky or have perfectly exposed shadows and darker areas, but never both at once?

The answer might lie in one of the least understood and often overlooked aspects of photography: Dynamic Range.

What is Dynamic Range,
and How Does it Affect Your Photography?

HDR photography gets around the typical limitations of a camera's native dynamic range by combining multiple versions of a photograph, taken at varying exposures, and combining them into a single image. 

Going back to our example scale of one to one hundred, the camera can only capture a specific range of information at any given time. But what if we took multiple images, changing the exposure setting each time, and then combined them? 

By taking five separate images—one to twenty, twenty-one to forty, forty-one to sixty, sixty-one to eighty, and eighty-one to one hundred—we can hypothetically capture 100% of the information in a scene. When we combine them in our favorite photo editing software, we can create an image that has plenty of details across the entire range of light to dark. 

Step #1: Setting Up Your Camera
The first and most important thing you need to know about HDR photography is that having a completely still camera makes things much, much more comfortable. Using a sturdy tripod and a remote shutter release (or the automated bracketing function if your camera has one) will make the workflow much more straightforward and help you create images with tack-sharp edges. 

Step #2: Capturing Your Frames
At its most basic, creating an HDR image requires at least two images at varying levels of exposure, thought having more images can help ensure smooth transitions from light to dark areas within your image. 

You will want to ensure that the subject is stationary and motionless throughout the shooting process, or your images may end up with artifacts such as ghosting or blurry edges. 

If you are just beginning, try taking a series of four images. Once you have decided that proper exposure for the scene (based on the average lighting throughout the composition), take a photograph set to -4 stops, a second at -2 stops, a third at +2 stops, and finally a fourth at +4 stops. 

This should give you (and your favorite photo editing software) plenty of dynamic range to work with when building the final image. 

Step #3: Building Your Image
Now that you have your multiple exposures captured, it's time to combine them into a single High Dynamic Range image. Depending on the software you use, there may be automated functions for creating an HDR image from a set of inputs, but for now, I'm going to cover the basic concepts of how to create the image yourself. 

First, you should import the image files and add each file to a separate layer within your project. Once the layers are created, you are going to need to decide for each area of the image, which of the exposures has the proper details, and that is the exposure that should show in that specific area. 

For example, if the -4 stops image is correctly exposed for the sky, but extremely dark in the foreground, and the +4 stops image is completely blown out in the sky but has just the right exposure for the foreground, you will want to let the -4 stops layer show in the sky and the +4 stops layer show through in the foreground. 

With each additional exposure you include, you are giving yourself (or your editing software) more information to work with and, therefore, more opportunity to get the exact right exposure across the full range of highlight, lowlight, and mid-tones. 

Manually creating an HDR image requires using some intermediate photo editing workflows, including lighting channels, blending modes, or the dodging and burning tools, but don't let that scare you off from trying. It can be great practice using some of these core photo editing features.

 
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What is Focus Stacking & How Does it Relate to HDR Photography?

When we create an HDR image from multiple exposures, we are aiming to create an image that goes beyond the normal capabilities of our camera. But increasing the effective dynamic range of our images isn't the only reason to use multiple photographs to create a single image. 

Focus stacking is another technique that many photographers use to create images that go beyond the normal limits of their equipment. 

Many photographers love the bokeh look, where the subject is in full focus, and everything in the background is a smooth blur, but sometimes we want to create an image that keeps everything in focus throughout the entire picture. 

When the composition includes objects very close in the foreground as well as far off in the distance, we can quickly run into the limitations of our equipment to produce sharp focus. You may have heard about how increasing the aperture number (making the hole smaller) can create a wider depth of field and allow more of the image to be in focus, but this isn't always the best solution.

When using smaller apertures (larger numbers), we can run into several problems. First of all, we may not have enough light to capture the image at the appropriate shutter speed. We may also find that even the maximum depth of field that our equipment can produce just isn't enough to get those cute flowers in the foreground while keeping the towering mountains the background in focus. Add to this the fact that some lenses can create unwanted effects and distortions as the aperture gets smaller. To avoid these issues, many photographers turn to focus stacking. 

Focus stacking, like HDR photography, requires us to take multiple images of a scene and combine them into a single photograph, however, whereas HDR images are taken at varying levels of exposure, with focus stacking we take multiple photos with different areas in focus and combine them into a single image with a depth of field far surpassing what our camera could typically produce. 

 
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