Calcite Springs, Calcite Springs Overlook, Roosevelt area, between Tower-Roosevelt Junction and Canyon Junction, Yellowstone National Park - Processed using the "exposure blending" technique, but using GND filters in the field could have yielded a different result

In the previous and first post from this series, My Experience Using Singh-Ray GND Filters, Part 1: Introduction, I wrote about the so-called dynamic range problem in photography, and the various solutions that exist to overcome it.  Graduated Neutral Density (GND) filters are one possible solution.

In this second posting, I describe the filters and accompanying equipment I chose, and attach the filters to my camera for the first time and share.

What are Graduated Neutral Density (GND) filters?

Graduated Neutral Density (GND) filters are optical filters that are clear on one half, and dark on the other. They are used to bring an overly bright part of a scene (for example, a bright sky) into the dynamic range of the camera’s sensor. They come in different shapes, including round filters that you screw onto the end of a camera’s lens like you would a polarizer. They also come in square (or rectangular) shapes, which most photographers tend to favor, as they allow you to adjust and move the filter to make the ND cut-off line meet the horizon, making square GND filters more flexible. With round GND filters, the ND cut-off line is directly in the center of the image, and many photographers do not frame their images with the horizon line at the center. Because of the flexibility that square filters allow, I decided to go down this route.

Aside from the square and round distinction, GND filters come in two categories: soft-edge and hard-edge. These terms are used to describe the transition between the clear and dark halves of the filter. A soft-edge transition is a more gradual transition. One would commonly use soft-edge filters when photographing scenes where the horizon line is not so easily defined, like some mountain or seaside landscapes. A hard-edge transition is a sudden transition. One would commonly use hard-edge filters when photographing scenes where the change in light is defined (some desert landscapes, for example).

Image courtesy of Wikipedia

The GND filters come in different strengths. These strengths refer to the amount of light that the dark portion of the filter cuts out, from one to five stops more dense than the clear part. Different manufacturers use different methods for measuring the density (or strength) of their GND filters. Singh-Ray sells filters in one, two, three, four, and even five stop strengths. Lee uses the filter grades 0.3, 0.6, and 0.9, corresponding to one, two, three stops respectively. Based on my research, Singh-Ray is unique in that they sell GND filters with a strength of four and five stops. The most popular strengths of filters are two and three stops, especially two stops. For unique lighting situations, one can always combine two filters together.

GND filters can be used with your camera in the following ways: You can get a filter holder (such as the ones from Cokin), which is a device that attaches to a lens, and that holds each GND filter in place. The filter holder is helpful to obtain a precise, exact placement of the GND filter. Some photographers, however, prefer to hand-hold their filter(s) in front of the camera, without the need to use a filter holder. The advantages of hand-holding are that it helps to reduce vignetting, offers more control, is faster, and doesn’t require the photographer to carry and work with extra gear in the field. Note that the filter holder option does allow you to place multiple filters in its slots (see pictures below).

Different manufacturers make and sell the filters themselves. Based on my research, I concluded that while Singh-Ray filters are the most expensive, they are also the highest in quality. They were designed by the late prominent landscape photographer Galen Rowell, and they are used by some of the leading landscape and nature photographers in the world. However, Lee also makes some excellent GND filters, and many photographers have been happy with the results that they have obtained using them. Cokin also makes GND filters, however I cannot comment as to their quality.

My chosen GND setup

The three components of a filter system. Image courtesy of Cokin

A filter system consists of three major parts, as shown in the illustration above: an adaptor ring, a filter holder, and the filters themselves. Let us look at each part one by one, and also look at which parts I chose.

Cokin Z-Pro Filter Holder

While different manufacturers make filter holders, I chose to go with the Cokin Z-Pro Filter Holder. Cokin makes filter holders in multiple sizes to accommodate the gamut of consumer and professional DSLR and video cameras. For the purposes of digital photography up to DSLR, Cokin makes filter holders in two sizes: P and Z size. For more details about the sizes, visit the page on Cokin’s Web site. Basically, the P size is a smaller filter, and the Z size is a bigger filter. I chose the Z size because my camera is a full-frame DLSR. I also plan to use this filter system with a wide-angle lens, and wanted the best setup to minimize vignetting that is possible when using this type of lens with a full-frame sensor.

Cokin Z-Pro 82mm Adaptor Ring (for use with my Canon 16-35mm lens)

Once I chose the filter holder, the need came to choose adaptor rings that will fit each of the lens that I plan to use with the GND filters. This decision wasn’t too difficult at all. I plan to use my GND filters with both my Canon EF 24-105mm f/4 L IS USM lens (which has a filter size of 77mm) and my Canon EF 16-35mm f/2.8 L USM (which has a filter size of 82mm). I simply chose the adaptor rings that will fit these two lens: two adaptor rings, one size 77mm, and the other size 82mm. I had no trouble finding the 82mm. However, I am having some trouble finding the 77mm. Apparently, Cokin is known for having delays in shipping their products to retailers.

One very nice thing about the Cokin filter system (or any other filter system), is that if one uses the square-shaped filters, it is possible to use them on a variety of lens of different sizes without having to invest in individual filters for each size lens. This keeps the cost down when purchasing filters. The rings themselves are reasonably priced at about $30 each size.

So now I had the filter holder and adapter rings chosen. I now had to choose the filters themselves. As said before, I decided to go with Singh-Ray GND filters. I purchased two filters: a tw0-stop soft grad, and a three-stop soft grad. I felt that this is a good starting set, especially for my upcoming trip to Grand Teton National Park. With time, I will purchase hard grads, when I return to the American Southwest for more shooting. Two-stop and three-stop strengths are just good numbers to have in a kit, in my opinion. We’ll see what results I am able to obtain using this “introductory kit.”

Singh-Ray packages the GND filters very nicely

Singh-Ray even provides a protective case with an optical-cloth liner for the each filter's storage

My recently-aquired Singh-Ray GND filters

That’s it!  That’s my basic “introductory” GND filter kit. Now, let’s put them on my camera…

How my GND filters attach to my camera

The Cokin Adaptor Ring screws on to the end of a lens (or the end of a UV filter if it has threads)

Each Cokin Adaptor Ring attaches to the threads located at end of the lens. If you’re using a UV filter that has threads like me (I’m using one manufactured by Heliopan), then the adaptor ring screws right over the UV filter. (a side note: I never, ever leave the glass of the lens exposed while shooting. I always have either a UV filter or polarizer on my lens at all times. Just good practice to prevent damage to the lens’ glass. It’s much cheaper to replace a UV filter than it is a lens’ glass!)

The Cokin Z-Pro Filter Holder slides down over the Adaptor Ring. Pins built into the holder prevent it from moving any further than it needs to

With the adaptor ring attached to the lens, the filter holder slides down over the ring. The peg located at the top of the filter holder helps to prevent it from slipping off the ring/lens assembly.

The assembled Z-Pro Filter Holder and Adaptor Ring

When the filter holder is securely attached to the ring/lens assembly, it’s time to slide the individual filters in. The Cokin Z-Pro filter holder provides slots for three filters. Some photographers prefer to cut off two of the slots, in an effort to prevent vignetting. As mentioned below, my final setup did not produce any visible vignetting, and at this time, I am leaving the three slots intact.

Sliding the GND filters in

A quick word about using polarizing filters with this setup: My polarizers do not have threads etched on the outside of them. As a result, it is not possible to stack anything else (like an adaptor ring) beyond a polarizer. If you need to use a polarizer for your shot, Cokin manufactures a drop-in polarizer that fits into one of the slots on the filter holder. You should see Cokin’s Web site for more details. Also see the illustration below:

Image courtesy of Cokin

The completed Z-Pro Filter Holder, Adaptor Ring, and GND filter assembly, ready for shooting

The Z-Pro Filter Holder with GND filter can be rotated along the Adaptor Ring, which in turn rotates the division between the graduated and clear parts of the GND filter - allowing for flexibility in composing your landscapes

Observed effects of vignetting: My above setup, which uses a Canon EF 16-35mm f/2.8 L USM (the widest of my lenses that I would ever use a GND with), a full-frame digital DSLR, and a Z-size filter system, yielded no observable vignetting at the time of this initial test and writing. Please note, however, there are many different combinations of cameras and lenses, and that vignetting can occur in some of these combinations, but not in others.

A side-view of the completed filter system

That’s all for now. I hope that this posting provided some useful information to anyone researching filter systems for their cameras.

Here are some additional useful resources:

http://www.great-landscape-photography.com/graduated-filters.html

http://en.wikipedia.org/wiki/Graduated_neutral_density_filter

http://www.my-photo-blog.com/graduated-neutral-density-filters

http://timsastroblog.blogspot.com/2008/12/cokin-z-pro-filter-holder.html (another great look at the Cokin Z-Pro Filter Holder)

———-

This is the second blog posting in a series of three postings that describe my initial experience with shooting landscapes using Singh-Ray Filters.

In the first posting, I wrote about the so-called dynamic range problem in photography, and the various solutions that exist to overcome it.  Graduated Neutral Density (GND) filters are one possible solution.

In the third posting, to follow after my upcoming fall 2009 trip to Grand Teton National Park, I report back on the results of shooting landscapes in GTNP using the filters.

Snake River Overlook, Grand Teton National Park - this landscape, processed using the exposure blending technique, could have been improved by using Graduated Neutral Density (GND) filters in the field

The Dynamic Range Problem

Most scenes that a landscape photographer would photograph contain elements that fall into one of two categories: bright and dark. For example, a landscape scene where the sunset is the main subject (like Snake River Overlook, Grand Teton National Park above) might include both bright and dark elements when photographed using only one exposure. The foreground (which might contain a buck and pole fence, a river, trees, bushes, etc…) might be dark, while the sky (containing dynamic clouds or a dynamic sunset) might be very bright. The difference between the brightest and darkest parts of an image is known as its dynamic range. If a shot has very bright highlights, dark shadows and everything else in between, it is said to have a wide dynamic range. The human eye is very powerful. It has the ability to perceive a very large dynamic range. It can perceive a scene with both bright and dark elements.  Unfortunately, our cameras cannot. As a result, without knowing much about dynamic range and how it works, one would either expose for the bright spots of a scene, or the dark ones.

Snake River Overlook - RAW unprocessed exposure, exposed for the bright spots

Snake River Overlook - RAW unprocessed exposure, exposed for the dark spots

As one can see, the top image which is exposed for the bright spots in the scene, shows some detail in the sunset and sky, but elements and detail in the foreground are lost (the foreground is underexposed).  The bottom image, which is exposed for the dark spots in the scene, shows the foreground detail, but the detail in the sky is washed out or lost (the sky is overexposed).  In both of these exposures, it would be very difficult (if not downright impossible) to restore the lost detail in post-processing.

There are several solutions to the dynamic range problem in photography:

1. Use the “exposure blending” technique (which I used for my Snake River Overlook, Grand Teton National Park composition above)
2. Use High Dynamic Range Imaging (HDR), a technique which is becoming widely popular
3. Use Graduated Neutral Density (GND) filters

Numbers 1 and 2 above require creating several exposures of a scene in the field, and later combining them using computer software (a program like HDRsoft’s Photomatix Pro) in post-processing.  I can do this, and I’ve done it before. However, my goal moving forward is to explore the use of GND filters (option number 3) and how they can improve my landscapes.

Why use Graduated Neutral Density (GND) filters?

Using GND filters, you are able to bring to the camera what your eyes see, both bright and dark elements. This without using any Photoshop or software post-processing. Taking photos of landscape scenes which include moving water (a waterfall or river, for example), can also be a problem if you intend to take multiple exposures to either blend them together or create an HDR in post-processing. The same problem applies to fast-moving clouds in a scene. GND filters help curb these problems. And of course, they help diminish the amount of time spent in front of a computer in post-processing. Flat out, GND filters are indispensable when the need arises to control the contrast range in any landscape image to avoid blowing out highlights, like dramatic skies. Many professional photographers attest to their usefulness and some say that they are among the best investments they have made for their cameras.

The outstanding, beautiful, and jaw-dropping work of photographer Patrick Smith inspired me to look into GND filters, and explore how they can help improve the quality of my landscapes.

———-

This is the first blog posting in a series of three postings that describe my initial experience with shooting landscapes using Singh-Ray Filters.

In the second posting, coming soon, I describe the filters and accompanying equipment I chose, and attach the filters to my camera for the first time and share.

In the third posting, to follow after my upcoming fall 2009 trip to Grand Teton National Park, I report back on the results of shooting landscapes in GTNP using the filters.