Graduated Neutral Density Filter

Term: Graduated Neutral Density Filter
Description: A photographic accessory designed to control and balance exposure levels within a scene featuring a significant contrast between bright and dark areas. Comprising a piece of optical glass or resin with varying degrees of light attenuation, the filter is transparent at one end and gradually transitions to a neutral gray tint at the other. When placed in front of a camera lens, the graduated neutral density filter reduces the amount of light entering the lens specifically in the brighter portion of the frame, thus preventing overexposure in that area while maintaining accurate exposure across the entire image. This tool is commonly used in landscape photography to capture well-balanced shots of scenes with stark variations in light intensity, such as capturing a properly exposed sky while preserving details in a foreground subject.

I’m not sure whether to call this a One-Shot HDR, or an HDR Panorama, or just a Panorama.  This image is created from four original frames, but they were panned and not bracketed.  So I’m just going to call it a one-shot HDR Panorama.  You can call it whatever you like!  😉

The Photo

 Nature Photograph(Click here to view a larger image!)

The Equipment and Settings

  • Nikon D70
  • Tokina 17mm f/3.5 ATX Pro (Extremely rare!)
  • Giottos Tripod
  • 1/3 sec @ f/16 & ISO 200
  • Manual Exposure, Manual WB, RAW

The Shooting Conditions

One technique for creating “One Shot HDR” images that few people talk about these days is an oldschool method- using a GND filter to manage the dynamic range of single exposures.

Some may argue that true HDR photography must be bracketed and “tonemapped” in order for it to be called an HDR, but in my opinion the term has become universal and is acceptable to use in describing any scene that has a high level of dynamic range regardless of whether it took one image to achieve, or multiple bracketed images, or other tools such as GND filters.

A brief explanation of what a GND filter is, for those of you “newschool” HDR photographers who may have never even shot on film before:  GND stands for Graduated Neutral Density, and usually it is a square filter that is mounted over your lens in a sliding holder.  The square filter is half dark, and half clear, with a gradual transition between zero and 3-6 EV’s.

Most commonly, you use a GND filter by placing the darker part over the bright sky in your exposure, while the foreground is not “blocked” by the 3-6 stops of neutral density.  Thus you can create a single that would have required a 3-6 stop bracket to achieve otherwise.

By the way, neutral density just means that the filter doesn’t have any sort of effect other than darkening.  The best GND filters have zero color shifting, while the cheap-o ones might give your images a slightly weird hue.  This used to be a huge issue when shooting on film, but now with digital photography you can usually correct any GND filter flaws with your temperature and tint sliders.

[FAQ: What is HDR Photography?]

Anyways, I created this image as a 4-shot panorama, with a 17mm lens oriented vertically on a crop-sensor DSLR.  The original, un-edited frames looked like this:

hdr-panorama-gnd-pan-original

The Post-Processing

Once again, I found myself browsing old archives from 2007 using Adobe Bridge CS6.  To watch a video on how easy it can be to hunt down old photos using Bridge and Windows Explorer or Apple’s Finder, click HERE!

I prepared the original frames in a two-step process:  creating the foundation for overall editing as quickly as possible, and spending time to fine tune the tones with gradients and local brushes.

I used the SLR Lounge Preset System (for Adobe Camera Raw CS6) to create a simple HDR foundation, basically brightening the shadows and reducing the highlights if necessary.  This image was slightly under-exposed, so I opted to leave the highlights and whites relatively neutral and just bump up the shadows.

Then I applied a small amount of burning & dodging and graduated filters, but I knew that I would rather complete that process after merging.  Click HERE to watch a video on how I use Photoshop CS6’s automated Panorama feature.

Check out the prepped original frames and the final image below:

hdr-panorama-gnd-pan-prepped

Nature Photograph

Take care, and happy clicking!
=Matthew Saville=

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