In the second act of "A Raisin in the Sun," when the matriarch of a black Chicago family announces her plan to leave an overcrowded apartment and buy a house, her daughter-in-law wants to know what sort of house. "Is there a whole lot of sunlight?" she asks.

"Yes, honey, a whole lot of sunlight," the mother-in-law answers.

This is the kind of moment that can be everything or nothing in the theater, depending on the skill of the players. So it is a large tribute to actresses Alfie Brown and Deborah A. Tidwell, and director Fredric Lee, that the moment is sublimely moving as rendered at the Studio Theatre. At its best, this "Raisin in the Sun" is as fortunate a union of actors and material as you're likely to find on a Washington stage at the moment.

Unfortunately, just when the production seems to be cruising along at high speed and high altitude, it has a tendency to dive without warning to depths of ghastly heavy-handedness. The descents are so steep and sudden that you have the feeling of being aboard a plane whose pilot is suffering periodic blackouts and being replaced, at intervals, by a hysterical flight attendant.

Lorraine Hansberry's 1959 play has not been produced much lately -- in part, I suppose, because of the musical "Raisin" (developed at Arena Stage before it went to Broadway in 1977), and in part because no one could hope to better the performances, preserved in the movie version, of Claudia McNeil, Ruby Dee, Sidney Poitier and the rest of the original Broadway cast. But when the Studio production is flying high -- which tends to be the case when Brown and Tidwell share the stage -- you're likely to be too swept up in the play for comparisons.

"A Raisin in the Sun" deals with a $10,000 life insurance benefit, the largest sum of money the Younger family ever has seen. Lena, the widow and beneficiary, means to use some of her windfall to finance her daughter Beneatha's dream of becoming a doctor, and some as a down payment on the house with "a whole lot of sunshine," which happens to be in an all-white neighborhood.

But her son Walter Lee dreams of putting the money into a liquor store he hopes to open with a go-getter friend. Walter Lee is "all wacked-out with bitterness" against his present job as a chauffeur and against the blank future he sees for himself.

"Eat your eggs, Walter," his wife tells him.

"On, damn my eggs!" he shouts back at her. "Damn all the eggs that ever was!"

Brown, who plays Lena, is the artistic dean of Baltimore's School for the Arts and the hostess of the Maryland public television program "Critics' Place." She is also a terrific actress, with a hugely expressive face and a voice of awesome depth and power -- and the ability to blend those natural assets into a fully realized performance.

Tidwell's portrayal of the stable, hard-working Ruth is the anchor of this production, and the unahppiness and anger that drive her to consider an abortion are emotions that, quietly registered, make a powerful impression. At the same time, as Lee has staged the play, she has a tendency to move abruptly from one mood or piece of business to another. She is continually called on to hum or sing to herself when something happens that the character can't handle -- and she makes the transition so transparently that you can almost hear the director whispering instructions in her ear.

Speaking of music, Lee has chosen to provide songs in all the scene breaks, starting them while the actors are still on stage, still acting. At the end of the play, with Lena along on stage, about to leave the apartment where she has spent most of her life, we are suddenly overwhelmed by an "especially recorded" rendition of a song called "We Could Be Flying," which includes the words "a touch of hope, a new beginning . . ." The result is jarring, and it detracts from a play and production that are perfectly capable of speaking for themselves, without musical commentary.

In constrast to this exercise in overcontrol stands Elliott Hill's uncontrolled performance as Walter. A talented actor, Hill likes to slam doors -- not just now and then, but every time he goes through one -- and with such violence that you're surprised to see the door survive (a tribute, I suppose, to Kenneth Wilson's solidly designed and built scenery). And when he isn't slamming, he's jumping, shaking, strutting and flailing, until finally his nonstop energy loses all meaning. It's a shame, because there are very effective moments sprinkled through this anarchic performance.

Among the supporting performers, Gregory J. Ford is a standout as Beneatha's Nigerian suitor, Joseph Asagai. Ford is very convincing and very funny, and his introduction to Lena -- who has hardly ever left Chicago, let along met an African -- is a real treat.

A RAISIN IN THE SUN by Lorraine Hansberry; directed by Fredric Lee; disigned by Kenneth Thane Wilson; costumes by Jane Phelan; lighting by Tomm Tomlison; special music by Donal Leace; with Debra A. Tidwell, Eston Leon Lewis II, Elliott Hill, Tia Powell, Alfie Brown, Gregory J. Ford, Vincent Brown, Gregory P. Cavanaugh and Joseph E. Kellibrew.

At the Studio Theatre through June 3.