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| an almost impossible exposure was captured using graduated neutral density filters in Yosemite's high country |
doing the impossible
This photo was made near the Glen Aulin camp in the Yosemite high country after sunset during our recent annual Yosemite expedition. I noticed that others in our group were struggling with this scene’s wide range of light levels which they described somewhat in disgust as an “impossible” exposure. Agreeing with the consensus, I nevertheless made high-and-low exposures for possible use later in producing a composite image. Then I decided to go into my “filter dancing” technique to try the impossible!
Let me first explain that for a time several years ago I decided to give up on using graduated neutral density filters. With the advent of the digital scanner for film images, it seemed that ND Grads were no longer needed to hold back the sky and other brightly lit areas in a scene that were well beyond the dynamic range of the film itself. You could, instead, simply make an exposure for the highlight areas and another for the shadow areas and then blend them into a composite image later. Yes, this was tricky with film but it could be done. Did I say tricky? Here’s a definition of film which helps to understand just how tricky film image blending can be.
Photographic film is a sheet of plastic (polyester, nitrocellulose or cellulose acetate) coated with an emulsion containing light-sensitive silver halide salts (bonded by gelatin) with variable crystal sizes that determine the sensitivity, contrast and resolution of the film.
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| composite frame shot for shadow detail |
Trying to match two pieces of this film concoction was dicey at best, but it could be done and it saved images where a graduated filter could not be used! With the further advent and development of the digital SLR camera, even newer techniques were born and there were many photographers who stopped using ND filters for good. Improved resolution of digital images then made solving the “high dynamic range” exposure problem a simple—if rather time-consuming—matter of computer blending. I found I now had the ability to capture information in both the shadows and highlight areas like never before—all in the same frame. . . Well. . .sometimes I did.
And sometimes I was still forced back to the two-exposure composite.
I’ve recently found after making many landscape images and prints that sometimes composites work for me, but most often they don’t. I can’t get them to look right, or natural. I wanted to return to using my graduated neutral density filters except that in a lot of situations there is not a clear straight line in the image to work with. More recently, however, I have adopted a routine of “dodging and burning’ a high-contrast image while photographing in the field—by handholding and manipulating my ND grads during the exposure. I call this method “dancing” with the filters—simply moving the filter around the image during the exposure.
No, this is not for the weak at heart!
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| highlight frame |
When I first set up the shot, I now begin by stabilizing and locking down my camera on a very substantial tripod so nothing can move during the exposure, then use either a cable release or self timer, and mirror lockup! Where the shortest exposure possible for this situation would “normally” be desirable, I now want the longest exposure. So I use the camera’s lowest ISO setting to help achieve a longer exposure that gives me additional time to “dance” with my ND Grad filters while the shutter is open. Many times I find myself exposing for 30 seconds or longer—holding the filter flat against the lens and moving as slowly and deliberately as I can. Like I said, it’s not for the weak at heart!
This method has a few drawbacks but many bonuses as well. I now shoot dozens of the same basic setup while shooting this way. No two exposures will be the same. A change in aperture will produce different results as will any changes in the exposure time.
There were two important breakthroughs for me when I adopted this filter dancing method. First, I found that when everything works the mid-tones in the image are brighter and more natural while the shadows have just enough information to show some detail. What’s more the highlights still hold the natural feel that sets off the composition. I also found that I could more easily hide the filter gradient line along uneven shapes, like mountains and valleys, making the filters usable where they weren’t before.
Now you know why the native Americans call me “Dances with Filters.” And now you may have a better idea of how I captured the “impossible” image above. I danced with two 4 x 6-inch Singh-Ray Graduated Neutral Density filters, a 4-stop hard edge “stacked” on top of a 3-stop reverse ND. I chose the latter because the “hot spot” was on the horizon and not at the top of the frame. The large, easy-to-grip filters were then moved during the exposure from the top-left corner down to where I thought the river’s edge to be. The motion was repeated several times.
To be honest, I never produced a composite image from the two high-and-low exposures I made. I could judge by what I saw in the two frames that I had managed to get it right in the field with the use of the ND Grad filters ... while I was doing the impossible!
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