In one wide open vista, scrubby, bright green pines sparkle in sunlight, backed by Bridalveil Fall tumbling lightly down a cliff side; the distinct granite crest of Half Dome looms in the background. In another, a heavy mist obscures stands of giant sequoias.
"He has such command of space, atmosphere and light," said Fine Arts Museums director Colin Bailey.
Other iPad images are overlaid, so viewers can see them as they were drawn, an animated beginning-to-end chronological loop. He tackles faces and flowers, and everyday objects: a human foot, scissors, an electric plug.
Some of the iPad drawings are displayed on digital screens, others, like the Yosemite works, were printed on six large panels. Hockey's technical assistants used large inkjet prints to reproduce the images he created on his IPad.
Exhibiting iPad images by a prominent artist in a significant museum gives the medium a boost, said art historians, helping digital artwork gain legitimacy in the notoriously snobby art world where computer tablet art shows are rare and prices typically lower than comparable watercolors or oils.
"I'm grateful he's doing this because it opens people's mind to the technology in a new way," said Long Island University Art Historian Maureen Nappi, although she described Hockney's iPad work as "gimmicky."
Writing about the historic shift of drawing from prehistoric cave painting to digital tablets in this month's MIT journal "Leonardo," Nappi said that while iPad work is still novel, the physicality of painting and drawing have gone on for millennia.
"These gestures are as old as humans are," she said in an interview. "Go back to cave paintings, they're using finger movements to articulate creative expressions."
Hockney, 76, started drawing on his iPhone with his thumb about five years ago, shooting his works via email to dozens of friends at a time.
"People from the village come up and tease me: 'We hear you've started drawing on your telephone.' And I tell them, 'Well, no, actually, it's just that occasionally I speak on my sketch pad,'" he said.
When the iPad was announced, Hockney said he had one shipped immediately to his home in London. He splits his time with Los Angeles.
He creates his work with an app built by former Apple software engineer Steve Sprang of Mountain View, California, called Brushes, which along with dozens of other programs like Touch Sketch, SketchBook Mobile and Bamboo Paper are being snapped up by artists, illustrators and graphic designers.
Together, the artists are developing new finger and stylus techniques, with Hockney's vanguard work offering innovative approaches.
"David Hockney is one of the living masters of oil painting, a nearly-600-year-old technology, and thus is well positioned to have thought long and hard about the advantages of painting with a digital device like the iPad," said Binghamton University Art Historian Kevin Hatch in New York.
Hatch said a "digital turn" in the art world began about 25 years ago, as the Internet gained popularity, and he said today most artists have adapted to using a device in some way as they create art.
A similar shift happened almost 100 years ago with the dawn of photography, he said, when innovations such as the small photograph cards and the stereoscope captured the art world's imagination.
And Hatch said there are some drawbacks to the shift to tablet art.
"A certain almost magical quality of oil paint, a tactile, tangible substance, is lost when a painting becomes, at heart, a piece of code, a set of invisible 1's and 0's," he said.
Hockney, who created 78 of the almost 400 pieces in the de Young show this year, isn't giving up painting, or drawing, or video, or tablets, any time soon. When asked where he sees the world of art going, he shrugged his broad shoulders and paused.
"I don't know where it's going, really, who does?" he said. "But art will be there."
