At Tanglewood, a midsummer night's what?

Caleb Mayo and Antonio Weissinger perform with the BSO in Mendelssohn's incidental music to "A Midsummer Night's Dream" Saturday in The Shed at Tanglewood.

LENOX - Onstage, the fairy chorus lit candles to sing its farewell. Out front, the audience lit answering candles (all electric, of course), plunging the darkened Tanglewood Shed into fairyland flicker and sparkle. Puck then stepped forward to deliver the adieu.

If the scene suggested cigarette lighters being lit at a rock concert, it nevertheless made a magical ending to Tanglewood's semi-staged version of Mendelssohn's "Midsummer's Night Dream" music on Saturday night. The production was a brave experiment, but an experienced cast of Shakespearean actors so dominated the stage that they virtually pushed the Boston Symphony Orchestra and Mendelssohn's mercurial music aside.

The adaptation, made and directed by Bill Barclay, probably worked well when first staged (under conductor Andris Nelsons) in Symphony Hall during the winter. Outdoors, it seemed too ambitious for a large, open space like the Shed. From a seat in the middle, the actors' rapid-fire delivery, though miked, was sometimes unintelligible, and the elaborate, athletic stage action, seen from an unraked floor, was too busy and distant to be clearly followed. Characters melted into one another.

No fault of the actors themselves. Karen MacDonald was a queenly but easily duped Titania, and Will Lyman made a dignified, if slightly daft, Oberon. The unstoppably busy Kiera Duffy and Abigail Fischer delivered the lines of just about everyone else, from Hermia to the rustics.

Confusingly, Mendelssohn himself mixed in the action. Caleb Mayo doubled as the older composer and Puck; Antonio Weissinger — an upcoming 13-year-old talent there — was both the young composer and a boy. Projections distracted from, rather than helped along, the stage business.

The opening scene, projected, showed a mature Mendelssohn composing his overture for his beloved sister, Fanny. (A problem: Mendelssohn actually wrote the overture at age 18.) Costumes were Elizabethan, with an outlandish ass' head for Bottom, who slept blissfully on a luxurious bed beside the deluded queen.

Mendelssohn's overture and suite of short pieces are intentionally "incidental" music, of course. Barclay's production, incorporating disparate chunks of Shakespeare's text, made it more so. Seated at the back of the stage to make space for the actors in front, the BSO, conducted by Hans Graf, sounded distant and indistinct. Members of the Boston University Tanglewood Institute Chorus innocently intoned the fairies' bits.          

If enchantment was lacking, the audience responded with a roar to an allusion to Tom Snout playing a "great wall" to separate Pyramus and Thisbe. In the end, even if you knew the play, a wall seemed to separate music and theater.                                                                                                                                                 

Let's not forget Garrick Ohlsson's final installment of the two Chopin piano concertos, which preceded the theatrical antics. The American pianist can thunder out runs along with the best of them but, as sequel to Friday night's performance of the first concerto, the Second emerged with the same utter naturalness — call it rightness — as he stretched and bent phrases to give them breadth.                                                       

Again, the slow movement enjoyed crystalline, almost unearthly beauty of sound and line: a true midsummer night's dream. The finale virtually danced. As on Friday, Ohlsson played a Chopin nocturne as an encore: the C-sharp minor, Op. 27, No. 2.                                                                                                                   

Sunday afternoon's concert came with a surprise encore.                                                                      

Instead of coming out with his cello after playing the Schumann Cello Concerto, Yo-Yo Ma returned with an arm around conductor David Zinman's shoulder and pleaded with the audience for help in finding his friend's lost dog. The 4 -month-old tan Havanese strayed from the Zinman's rented house in Lenox that morning, Ma said, and hadn't been seen since. Call the Lenox or Stockbridge police, he urged, giving their phone numbers.                                                                                                                                                           

Ma alerted — at a guess — 12,000 pairs of eyes in the huge crowd that thronged the grounds, lots and roads to hear the superstar cellist on the fine summer afternoon. However, the program, like the pup, seemed at times to lose its way. Even Ma, with his fabulous technique and expressive range, could not energize the always problematic Schumann concerto, composed shortly before the mentally disturbed composer threw himself into the Rhine.

The veteran Zinman, replacing Christoph von Dohnanyi, who had injured himself in a fall, led a nicely detailed performance of Mozart's "little" G minor Symphony, No. 25, bringing out the storm and stress that came to full fruition in the "big" G minor, No. 40. He concluded with a drift through Schumann's Symphony No. 2. All the elements were in place but fires only dimly lit the romantic passions. The BSO sounded tired. Bring on the candles.