For a while Friday night at the Filene Center, it seemed possible that the scenery would be the best element in the Wolf Trap Opera Company's production of Benjamin Britten's "A Midsummer Night's Dream." Considering the quality of the set (designed by Henry Bardon for the National Arts Centre of Canada), that might not reflect too badly on the performers -- but the fact is that on opening night this production got off to a slow and rather unfocused start.

Act 1 seemed devoted largely to efforts, by singers and sound technicians alike, to work out a modus vivendi with the sound system. By the end of Act 3, the electronics were going smoothly enough and the singing and acting were coordinated at director Leon Major's usual high level of imagination, but some of the voices never got around to projecting words rather than tone. It might be worthwhile for the company to use surtitles in the Filene Center even when the text is in English -- though that kind of precaution seldom seems necessary in the Barns.

Britten's opera is a very special kind of experience -- not necesssarily congenial to everyone who goes wild over "La Traviata" or "Tales of Hoffmann," but strongly imbued with flavors unlike those of any other opera.

The Wolf Trap environment enhances that part of the flavor which is related to the feeling of a forest at night. The grass, shrubs and trees around the Filene Center seemed a continuation of Bardon's wonderfully atmospheric set -- which, with the lighting by Neil Peter Jampolis and the costumes by Michael Stennett, formed a symphony in shades of green, with bold dashes of brown and bits of burgundy for contrast.

Britten's music is equally atmospheric. Sometimes it seems to echo the two great orchestral song cycles he composed about night, dreams and fantasies: the Nocturne and the Serenade.

The composer's style accommodates each of the three main categories of beings who fill the stage: fairies, members of the Athenian upper classes and workmen who aspire to be actors.

The music is ethereal, earthy, often pointed in the instrumental comments on the action, but at its best when weaving a gossamer screen of sound to match the setting and action. Richard Woitach deftly underlined instrumental felicities while keeping the focus of attention solidly on the voices, where it belonged.

The workmen/actors, who put on the "lamentable comedy of Pyramus and Thisby," nearly stole the show from the mortals whose love lives get hopelessly tangled and the fairies whose spells are responsible for the confusion.

For long segments of the opera, the stage is dominated by Alan Held, who is impressive both musically and theatrically in the role of Bottom. William Cotten also performs well as Flute, and the whole crew for the opera-within-an-opera is excellent.

As Oberon, Drew Minter turns in his usual near-flawless performance, with a fine partner, Jeanine Thames, in the role of Tytania. Paul Austin Kelly, Cheyne Davidson, Emily Manhart and Ann Panagulis, as the four young lovers, confirm the positive impressions they made earlier this season.