YELLOWSTONE NATIONAL PARK - It must have looked a little strange to passers-by on the boardwalk as Steve Wood knelt to take a photo of a small, plastic toy grizzly bear and cub perched on a bench in front of Old Faithful geyser.

But it was Jeremy Sullivan's way of introducing his photography students to the concept of depth of field - having objects close and far away in focus at the same time.

"The thing that's fun for us is these folks are on vacation so everyone is in a good mood, and we're in a beautiful place," Sullivan said.

Sullivan, of American Park Network, is in charge of the free camera workshop, with all new digital photo gear, that traveled to three of the nation's grandest national parks this summer. The program is part of Canon's Photography in the Parks photo workshops. Xanterra Parks and Resorts partners to provide lodging for the crew. This is the third year of the seminars.

American Park Network, publishers of park guides, puts together the six-and-a-half-week tour that starts in Yosemite, moves on to the Grand Canyon and finishes out in Yellowstone this weekend. Photographic equipment manufacturer Canon provides the latest digital cameras and lenses, such as the $2,000 Canon EOS 5D body, equipped with lenses that range from 18mm up to a huge 500mm that retails for around $5,800.

"We get a whole range of folks with different photography experience," Sullivan said. "Some people will come up and say. 'I want to try a telephoto lens.' Some people want to demo a particular lens."

Others will even come back a few days in a row to try different lenses and camera bodies, or in the case of two students, take part in a workshop in Yosemite and then in Yellowstone.

Steve and Karen Wood of Cody drove to Old Faithful on Thursday to take one of the two-hour workshops.

"It just seemed like a good thing to do and to see the park," Steve Wood said. "Plus, it's been a really long time since I've held a good camera in my hands."

Wood, 60, is a retired John Deere worker who moved to Cody from Walcott, Iowa. Over the years he has owned Nikon and Pentax film cameras, but never one of the newer digital models.

"Now I know what I want for Christmas, a lot earlier than Christmas," Wood said.

Rob Cude, of Idaho Falls, Idaho, brought his 12-year-old daughter, Maddie, to the workshop to give her ideas on composing photos with her new digital camera.

"She won't listen to me," he said. "I've been shooting since I was a kid, always film and slides.

"I thought we'd come up here and give her a little more education than out of a book."

Sullivan, a former park ranger who lives in Seattle, said it's hard to compress a lesson into two hours.

"We're always fighting the balance of talking too much and getting them to click the shutter," he said.

Wood said the class provided good, basic advice.

"I'm learning a lot of stuff I used to know a long time ago," he said. "This is a good lesson. I'm finding I am doing some good things accidentally."