Photography

High Dynamic Range Photography

Posted in Uncategorized by Diana Eftaiha on September 14, 2010

Dynamic range in photography is basically the divergence between the brightest and the darkest spots in a sight. The larger the difference, the bigger the dynamic range the pic is said to have. A scene with high dynamic range is also known as a scene with high contrast.

To be honest film and digital cameras have their limits when registering scenes with high dynamic range or high contrast. The challenge lies in their power to register the brightest imformation and the darkest imformation of the scene simultaneously , without any detail loss . This becomes especially hard with high contrastive scenes, such as really bright skies against deep shadows. Naturally , film cameras record a lot higher dynamic range than do digital sensors. But still, both are not adequate , for nothing is more adaptive and flexible than the human visual system.

The good news is, in this era of digital revolution, nearly everything is possible . That said, there are mainly 2 ways to defeat the limitation of our digital cameras in capturingfull dynamic ranges of scenes. First suggestion would be to make 2 exposures of the exact same scene. Once, you expose for the highlights of your scene (you take the light metering indication off the brightest area of the scene). And the second is to make an exposure of the exact same scene, this time exposing for the shadows (taking the light metering reading off the darkest area of that same scene). You then finish yp with two photos of the exact same scene. One recording all highlight information , and the other recording all shadow information . You then can merge these two photos using a photo editing software of your choice , let’s say Adobe Photoshop or Photoshop Elements, selectively obscuring under- and over-exposed spots of each take and presenting the correctly exposed regions of both. This way you end up with one correctly-exposed photo showing the full dynamic range of your scene.

This method works great for still-life photography, landscapes, and other imagery involving non-moving subjects. And you need to use a tripod to make sure the camera doesn’t move while trying to record two exposures of one scene. There’s a drawback to this method though, and that is taking 2 photos of an exact exposed scene can be difficult at times wherever your scene is at constant change, such as photographing wildlife, people, landscapes with fast moving clouds, and so on. Not to worry though, cause here comes the second method that you can use alternatively to record your own full dynamic range masterpiece.

The second method is easy and much more flexible to deal with in the case of shooting non-still imagery, or when you don’t have a tripod to hold still your camera and forestall movement. It goes as follows: you need to shoot in RAW. Just one image per scene this time, and then you download your RAW photos onto a RAW converter software of your choice. I personally use Adobe Photoshop’s Camera Raw. It’s a glorious, easy to use, and easy to understand software. And you can master it in no time. It installs automatically once you install Adobe Photoshop or Photoshop elements.

So what you do is open your raw images in camera raw, and construct two conversions of the same pic . Once tuning your photo exposure settings to appropriately show   all highlight details (bright areas details). And the other, tuning your photo exposure settings to appropriately bring out all shadow details (dark areas details). And then you merge the two converted photo using your photo-editing software. Just like before, you selectively hide under- and over-exposed areas of each image and show the correctly exposed areas of both. And once again you end up with a full dynamic range shot of your scene.

Graduated neutral density filters can also be used to expand   the dynamic range of a scene that can be exposed   on photographic film or digital sensor. The graduated neutral density filter is mainly split in two halves. The top half is dark, and works to hold back light coming from extra bright areas of the photograph . And the derriere half is clear, allowing a more light to register from dark areas of the sight. The filter is   laid in front of the lens at the time the exposure is made, with the dark half placed over a scene’s high-intensity region, such as the sky. The resolution is more even exposure in the focal plane, with increased detail in the shadows and low-light areas. Though this doesn’t increase the fixed dynamic range available at the film or sensor, it stretches usable dynamic range in practice.

It is also worth mentioning that you can take advantage of high dynamic range scenes to expose for excellent stark, dark silhouettes. You should also know that your digital images may be in fact holding more dynamic range that you can actually see. Having a high quality monitor that is cautionly profiled and calibrated is essential in your photograph editing workflow, and is something we all should be cognizant of, and well informed about. in the end, it is the tool you make your color and brightness adaptation   conclusions   with, so it is very crutial to be able to trust what you see on your screen display to be able to make those conclusions .

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