But the decades have changed Fielder. He still finds calm here -- but now, apprehension.
"Well, Nature is challenged more than ever these days," he said. "We've got a warming planet. We soon will have nine billion people on the planet visiting places like this. We need to protect it."
That's what drove President Lyndon Johnson to sign the Wilderness Act 50 years ago, protecting America's outdoors.
- Celebrating 50 years of American wilderness ("CBS This Morning")
To celebrate that anniversary, Fielder hit the road for a year showing his pictures, selling his books, working up to this night matching John the photographer with that other Colorado John, John Denver -- his music played by the John Adams Band.
It filled a downtown Denver concert hall -- the wonder of Nature, with a warning.
"Nature is being lost very quickly because of climate change," said Fielder. "And I want to be a part of the community of people that truly care about four billion years of the evolution of life on Earth.
"And one of the best ways to share with people how special this is and why it needs to be protected forever is through photography."
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