Graduated Neutral Density Filters

Slide film has latitude of about 5 stops, with digital being a little more at around 6 stops. As photographers we always want to expose properly for our subject. My definition for correct exposure is to have the correct tone with detail. White snow can be white, be it also should show the fine texture of the snow. A black bear is black, but I also want to see the detail in the fur.

	Pasque Flowers at sunset taken with a 3-stop GND filter

I will generally tell a photographer to base their exposure on the most important element in your image. A black bear cub in a white birch tree would need to be exposed for the cub and let the tree be a little over-exposed. Photographing a mature Bald Eagle I would expose for the white head and let the brown feathers be a little under-exposed. No medium whether film or digital will be able to show detail on the extreme edges of its latitude, that is why it is necessary to expose for the main point of interest in your image. However when doing scenic type of photography there is help for us photographers. Graduated Neutral Density Filters will allow us to take the brighter part of the scene to make it more in balance with the rest of the scene. I will generally try to achieve about a ½ to 1 stop difference between the brightest and darkest areas. It is important to always let the brightest part still be lighter than the rest of the image. Neutral Density Filters will come in two different ways - hard edge and graduated. They also will come in 1-2-3-4 stop difference. A hard edge Neutral Density will have a very definite transition from light to dark. So if a photographer is using a hard edge the image must have a very definite line such as a horizon to hide the light to dark line. I use only Graduated Neutral Density which is sometimes referred to as soft edge.  This line is very subtle and gradually makes the transition from light to dark. The gray of Neutral Density filters is neutral and it will do nothing to change the color of your image but will only affect the exposure of your image to allow the lighter and darker areas to be more closely in balance. I commonly use GND filters when shooting sunrise/sunsets, reflections, mountains with snow capped peaks, etc.

My GND filter of choice is the Cokin rectangular filter and the P series filter holder. At present I only have 1, 2, 3 stop GND filters. I will usually just look at a scene and determine what filter I want to use. As I look through the view-finder, I will slide the filter up and down to find the best position to bring the light and dark areas more in balance. If your camera has a preview button, sometimes this feature will make it easier to see the transition line of the filter.  If necessary I may also use a different GND just to compare the difference. Some photographers may spot meter the light area and the dark area and notice the stop difference and choose a filter based on this method. Always remember that a naturally light area should always be lighter. While taking the image I rely on my camera’s reflective light meter for it measures the light going through the GND. I will meter the scene based on what I want my subject to show. I may bracket in 1/3 stops which will allow me to make a comparison. Although I now shoot digital, I will still use these filters instead of using the computer. I am a firm believer in getting it correct in-the-field and this will save much computer time. I would much rather spend the time in-the-field than sitting at my desk on my computer.

		Roscoe Prairie Sunrise taken with a 2-stop GND filter

Like many things in photography there will be some additional hurdles that may need to be jumped. When using the Cokin P Filter Holder and wide angle much more than about 35mm will cause the lens to pick up the edges of the holder. This will show as dark edges around your image. To offset this I cut the very first part of the holder. This holder is designed to allow use of two filters.  I never use two so cutting the first slot will allow me to use my 28 mm lens with no problems. However if I use a wider angle I usually just hold the filter in place with my fingers.  Just be sure your fingers are not in the way. A photographer can also use gaffer tape and tape the filter to the lens. This tape will not leave any residue on the lens. If shooting into the sun such as in backlighting, the filter will add to the act of “flaring”. These bright “donut holes” are created as the light bounces around the glass inside the lens. The filter just adds to this problematic curse that we all have to deal with. I usually just try to keep the brightest part out of the scene, by moving the sun outside the frame. This will help somewhat, but it also may not be the image that you are after. These “donut holes” are easy to see through the view-finder, try changing your composition so they are in brighter areas not darker areas. Although they are still problematic, it will make it easier to accept. Also try adding additional shade by using a hat or some other device to shade the lens.

If you are not using Graduated Neutral Density Filters, I highly recommend that you try using one or two. These filters will allow a photographer to make an image of a scene that would be virtually unacceptable and could turn it into an award winner.

View Previous FYI articles