According to French photographer Henri Cartier-Bresson's definition of the "decisive moment," a great picture is the convergence, in one frame, of a spark of humanity and a perfect composition. A bike cruising by an intriguing staircase at just the right velocity. A fellow skipping over a puddle with both feet in the air.

Ultimately, decisive moments are the intersection of good luck and a good eye. And James Nares, who is a painter, knows something of the split-second recognition of a good picture. His work, like Cartier-Bresson's, depends on preserving just-right moments.

The paintings by the London-born New Yorker begin and end with a single gesture applied in just a few seconds. He pilots a brush -- his are self-made, some as much as a foot wide -- across a white canvas like a plane aborting its landing: The brush swoops in on the approach, skims the surface and rises up again. That's it. One color. One wave of the arm. Done.

Would that it were so easy. It takes Nares from 50 to 300 attempts to achieve the result he wants: a brush stroke with genuine charisma. That happens only when the variables come together -- the architecture of the gesture as it sits on the canvas combined with some ineffable zing. The right picture may defy calculation, but if you're Nares, you know it when you see it. And if he's not pleased, the artist puts a squeegee to the surface and takes the ink right off. And tries again. And again. With the brush dipped into the same batch of paint for each go-round, the process turns rhythmic and meditative; Nares becomes a conduit of his own pictures. "When they work, they seem preordained," he says.

The time it takes Nares to make a successful painting isn't much more than it takes a photographer to open his shutter. Nares' paintings track a moment and expand it. As when, the painter says, you witness a car accident. Time expands.

And when they're right, as each of his five paintings on view at G Fine Art is, they evoke images beyond their simple selves. A few even look like photographs. The slick ground he builds over the canvas or paper doesn't allow paint to seep in. Instead, the pigment dances on top in rivulets or ribbons. Some involve several separate brush strokes -- three perhaps -- that could be slips of satin whipping in the wind. But the standout piece here, for its sheer bravado, is the nearly seven-foot crimson "That Mississippi River Painting." Despite the title, those splashes of paint jutting off seem nearly calligraphic -- the rich red pigment evokes the art of Asia, and the arching shape of the thing looks like a Chinese dragon off some dynastic scroll.

If Nares catalogues the decisive gesture, then Maggie Michael, who is also showing at G, catalogues the decisive pour. Her paintings, created in the same all-or-nothing manner, are of blobs. (I wish there were a better word -- her shapes aren't exactly elegant but they aren't ugly, either.) Michael pours thick latex paint, the kind you'd use on your house, into rounded shapes more than a foot across. Instead of using canvas she pours pigment on a rectangular panel of plexiglass. After rehearsing the movements like a golfer taking a few practice swings before the tee-off, she lets the paint drip. The resulting shape either works or it doesn't.

For Michael, there's another hitch -- she's got to get two blobs right. Her paintings are called "Clones" and all depict pairs. The two never match exactly. How could they? But she aims at getting them really, really close.

At G, six of Michael's panels are hung in a row. They work particularly well together as their variations in form and color converse among themselves. Warm and cool gray, charcoal and cream are interrupted by one piece in bright blue. The blob forms are similar, but differences emerge out of the corner of the eye. It seems the best way to understand one panel is by looking at its neighbor.

There's been a recent push to represent scientific and biological concerns in contemporary art. Michael's is one of the most classical, painterly reactions to those concerns I've seen so far. Her references to science are tangential -- the slide-shaped plexiglass, the titles. In each piece, paint remains king.

Mikel Glass at Century Gallery Painter Mikel Glass is a realist obsessed with surrealism. This presents a problem. See, Glass paints as old-fashioned academic realists do, attending to lifelike detail and working by observing the objects in front of him. But he's not a big fan of the flowers and fruit of still lifes. He'd rather depict creatures he's fashioned out of mangoes and peppers, or broken doll parts. So he does a little of both, inserting surreal imagery into a traditional framework.

Like a dutiful realist, he constructs a tableau before laying brush to canvas. Where a still-life painter working in the Dutch tradition would arrange tulips in a vase perched on, say, a classical column, Glass inserts yellow, purple, orange and red rubber gloves into a vase he's perched on an upturned pail. He calls the piece "Full Bloom."

Glass's realist-painter buddies scoff at his weird subject matter, his avant-garde friends at his traditional approach. Ultimately, Glass's work will continue to confound both camps. But the battle between Rembrandt and Freud, as depicted on Glass's canvases, makes for meaty spectacle.

James Nares and Maggie Michael at G Fine Art, 3271 M St. NW, Tuesday-Friday 11 a.m.-6 p.m., Saturday 11 a.m.-5 p.m., to Dec. 14.

Mikel Glass at Century Gallery, 919 King St., Alexandria, Tuesday-Friday 11 a.m.-7 p.m., Saturday 10 a.m.-8 p.m., Sunday noon-5 p.m., 703-684-6967, to Nov. 19.

Spontaneity preserved: "That Mississippi River Painting" by James Nares, above, and Maggie Michael's "Clones," both at G Fine Art in Georgetown.Mikel Glass's rubber-glove still life in "Full Bloom" at Century Gallery in Alexandria.