My Experience Using Singh-Ray GND Filters, Part 2: Gear

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).

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

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.

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.

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.”

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

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!)

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.

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.

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:

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.

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)

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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.

Tagged as: Graduated Neutral Density Filters, Singh-Ray