The Story Behind the Photograph
The Bighorn Sheep
When photographing wildlife, one usually uses a fast shutter speed to stop action. Mary and I normally do, and with our latest digital SLRs our default ISO is 400, and we often use 800 for our second choice for the default ISO. That allows us to use shutter speeds of 1/2,000th for many shoots, and slower speeds when there is less light. Even then, we're often not shooting at speeds slower than 1/500th. In the old days of film, 1/500th was a fast shutter speed, so how things have certainly changed!
We were photographing a small herd of Rocky Mountain Bighorn Sheep on our latest Yellowstone Fall Photo Tour along the roadside in late afternoon. These sheep often climb down the cliffs to feed at a roadside saltlick, but occasionally the sheep will cross the road and continue down to the river's edge. The light was low, for although it was still three hours before true sunset the steep canyon walls created a dusk-like atmosphere below.
As I said, normally we immediately consider using a fast shutter speed to stop action, but earlier I had been doing some very slow shutter speeds of streams, often using the Singh-Ray Variable Neutral Density Filter, so when the sheep moved close to the river's edge inspiration struck. The light was low enough that I didn't need to use a neutral density filter, provided I used a small aperture. At f20 my shutter speed was .8 seconds, slow enough to create the 'angle hair' or 'cottoncandy' appearance on the river. The sheep were actively feeding, pausing only occasionally to look up, and those moments were very brief and rare. Luckily, of the four frames that I got off before the sheep moved on I managed to get one critically sharp, as the sheep paused, motionless, during the slow exposure.
The sheep moved further down stream and from our vantage on the road we had several more shooting opportunities, but now the sheep were moving. Accordingly, I reluctantly switched to a faster shutter speed, a whooping 1/50th of a second, as I kept a relatively small aperture of f10. Quite honestly, I no longer remember why I chose f10, but I'm hoping that at the moment I had used my Depth-of-Field Preview Button and decided that f10 provided more detail and looked better than shooting wide-open would have provided. I'm wondering, because 1/50th is still a slow shutter speed for a moving animal, but that slow shutter speed did create some water blur which I find more interesting than when water is 'frozen' at speeds of 1/250th second or faster.
I'd have loved to have had the sheep pause right on the shoreline of this fast-moving water long enough for a shot. The sheep did go to the river's edge, but the ewe's head never stopped moving and it barely paused before stepping back into the thick brush. Hopefully I'll have another chance next year, and I might improve upon the image I envision, and that I captured, somewhat, in the opening image.
For more information on our 2011 Yellowstone Trip, read our Trip One or Trip Two trip reports.
Past Stories Behind the Photograph
The Raccoon
The Pileated Woodpecker