The imaging sensor technology has been advancing rapidly in recently years. However the sensor dynamic range (DR) is still not quite wide enough to be comparable to human eyes, let alone capture the high dynamic landscape scenes.

Have you been struggling to expose the sky properly but the main subject or foreground turned out too dark? Or you managed to expose the main subject but the sky was completely overexposed and appeared washed out? You were disappointed and frustrated, and wondering if the big name camera manufacturer’s next $8000 product is what you need… You are not alone with these dynamic range challenged landscape photography situations. Here are some tips that may help you out without breaking the bank.

Shoot RAW format

Many, if not most, people with a raw-capable camera shoot jpg for the convenience of it. It is quite understandable: With raw format, you can expect to shoot less photos with a given memory card capacity. You have to process the photos first before sharing them with others. RAW files are also large that they fill up your hard drives faster than jpg, and your computer may need an upgrade to avoid chocking up during raw processing. Some even claim the jpg quality is just as good as the raw

The truth is, jpg files are processed from the raw data captured by the camera. The camera, with its limited brain power, decides what’s good for you and generate a jpg file from the raw data. It might be over sharpened, or have too much contrast (you may loose DR with higher contrast). It also reduces the bit depth from 12~16 to 8. You will have 32 or 256 times less brightness levels to work with if you shoot jpg. The bit depth is very important when you are trying to extract details from highlights or shadows. For more information about raw format, please read the articles Understanding raw files by Michael Reichmann, and The raw truth by Michael Tapes.

Shoot at low ISO

In general, cameras lose dynamic range rapidly with the increase of ISO settings. The Nikon D200, for example, loses almost two full stops going from ISO100 to ISO400. With a few exceptions, sensors have the maximum dynamic range at lowest ISO setting. Shooting with the ISO that produces the largest DR will help to preserve the details.

Expose correctly

If you underexpose too much such that the signal in shadow area is at the same level of sensor noise, or overexpose too much such that the highlights are clipped, you will not be able to recover the details in post processing. As a photographer, you will need to determine what details are more important and expose these details properly. Do not worry too much about clipping highlights or shadows if they are not important.

An interesting suggestion I have seen is “expose to the right”. Basically, the bright tones contain more levels than the dark tones. By exposing to the right side of the histogram, but not so far as to blowout the highlights, the entire tone levels offered by the recording bit depth can be utilized. When the scene contains too much dynamic range, and the highlights (often, skies in landscape photography) are more important than the shadows, the only logical choice is to preserve the highlights. You can try to recover shadows and adjust the brightness of other parts of the photo in post processing. You might be surprised to see how much you can recover from shadows if you shoot raw. Read my previous post Push processing with digital camera for an example.

High dynamic range (HDR) photography

If the camera cannot capture the dynamic range in single shot, you can shoot a series of photos at different exposures to capture all the details from shadows, mid tones, and highlights. The photos can then be merged into a single photo that contains the details from a scene with very high dynamic range. Very often, HDR photos may look surreal. They are indeed unreal because the photos with real high dynamic range are difficult to present properly on screen and have to be tone-mapped so they look nice. For HDR shooting tips, please read Exposure bracketing for HDR photos.

Use graduated neutral density filters

GND example
The photo on the left was shot with a 3-stop graduated neutral density (GND) filter with a hard edge, the right without any filter. The photo with the GND filter is more evenly toned and color in the sky is more saturated and pleasant. The other photo has slight desaturated (washed out) sky and dark foreground. GND filters work well in situations where you have clearly separated bright and dark parts of the scene. You can get a good result without spending too much time on computer. In more complicated cases where the highlights and shadows are difficult or impossible to separate, you will found HDR photography more appropriate.
Posted in: Tips and Techniques on October 5th, 2007. Trackback URI
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