A new production at the Metropolitan Opera is at the very least a costly undertaking. Last season, two of those undertakings paid off memorably in artistic terms - Otto Schenk's superb staging of Offenbach's ''Les Contes d'Hoffmann'' (designed by Gunther Schneider-Siemssen) and director-designer Franco Zeffirelli's breathtakingly beautiful presentation of Puccini's ''La Boheme.''
This year, the first new production of the season was Mozart's ''Idomeneo,'' staged and designed by Jean-Pierre Ponnelle and received with justifiable acclaim. Now, however, the house has allowed on its stage a production of Verdi's ''Macbeth'' that should never have gotten past the talking and preliminary design stage. (On Dec. 18 it will be aired nationally on the radio - check local listings.)
Sir Peter Hall, the noted stage director, was in charge of the action, and John Bury was in charge of the designs. Together they put Peter Shaffer's ''Amadeus'' on stage to well-nigh universal critical celebration. But neither seems to have a notion of what opera staging requires. Mr. Bury's sets are a series of hung drops poorly detailed and essentially unlit by Gil Wechsler. They are ugly and ill-proportioned for the singers on stage. Sir Peter's direction seems to lack common sense, and in several scenes theatrical instincts seem lacking.
The production evidently attempted to give a modern audience the feeling of the Paris premiere of Verdi's 1864 ''Macbeth,'' in a version tailored for that city. Paris always insisted on a ballet, among other conventions. The reports of the Metropolitan's own opening night of this production suggest it was one of the most uproarious in recent Met history. Throughout the evening, the sets, the direction, and even the singing were greeted with derisive laughter and booing. When Mr. Bury and Sir Peter emerged with James Levine at show's end, they were booed.
By the fourth performance, many of the reported sillier things had been changed. But one was still always aware of trapdoors, wires for the flying (yes, flying) witches, and all the other mechanisms employed for the so-called effects.
How does such an evening come to pass? Why did no one at the Met say, ''This will not do''? New York's two other major opera houses have general managers willing to go out on a limb and say just that. It is the least that should be expected, considering the hundreds of thousands of dollars involved and the fact that the house must use the production for years to come.
The ''Boheme,'' ''Hoffmann,'' and ''Idomeneo'' meet this requirement. The directors involved are brilliant stagers of opera. Mr. Hall's record, however, is primarily theatrical, as is John Dexter's - he used to be director of production at the Met and is responsible for several dour Met stagings of Verdi operas. It is clear that good theatrical values do not work in opera without some concessions to the nature of the art form, which have not been made here.
The music contains the kernels from which the dramatic action must be unfolded. Sir Peter and Mr. Dexter fight that music all the time. Singing into a 3,800-seat theater demands entirely different body language than acting in an 800- to 1,200-seat house, but the myth today is that contemporary theatrical techniques can be applied wholesale to the opera stage. It does not work.
We have great singing actors around, but their style is inextricably related to the process of singing. They are not Royal Shakespeare or Stanislavsky thespians. Many more of our finest singers are not very good as actors. Sherrill Milnes, who sings the title role in this production, falls in the latter category. Sir Peter did very little to try to make his lurching and staggering convey much. On the other hand, his work with Renata Scotto as Lady Macbeth was scaled to a tiny theater: Seen through opera glasses, her facial expressions were varied, interesting, but unspontaneous.
Mr. Milnes is in excess of six feet tall. Miss Scotto measures in at not much over five feet. Side by side, they were quite a mismatch. John Bury's sets featured doors and archways nearly as high as the proscenium and furniture that seemed to come up to Miss Scotto's chin, dwarfing her presence.
Vocally, the performance I attended - the fourth in a run of 11 - was spotty. The dramatic soprano role of Lady Macbeth was never anything Miss Scotto, a lyric sorpano best suited to lighter singing, should have undertaken, and the Met is wrong to have encouraged her. Even her lyric soprano performance falls far short of its former brilliance. Based on the 1973 revival, a recording, and this performance, I feel Mr. Milnes appears not to offer a great Macbeth, despite his justified stature as one of the leading Verdians of the day. Giuseppe Giacomini was vocally out of sorts as Macduff; Ruggero Raimondi was a solid Banquo.
The decision to include the mediocre ballet music was perhaps the first desperate flaw. Stuart Hopps's lurching, hopping, cavorting choreography was a consistent cause for laughter, even at the fourth performance. In the pit, Mr. Levine led a superb performance that turned this score into something major, and monumental. But as music director, he should have used his authority to see to it that such productions never get on this stage. Tannhauser
Happily, TV audiences will see the Met the way it should be, in one of its finest productions of a Wagner opera, ''Tannhauser.'' The performance of Dec. 20 will be taped for airing March 23, 1983, on PBS - check local listings.
The production, directed and designed by that superb team of Mr. Schenk and Mr. Schneider-Siemssen, has been discussed numerous times in these pages. The current cast is a fine one, though it features neither of the singers who made the first night so fine - James McCracken in the title role, or Leonie Rysanek, the definitive Elisabeth of the day. The only holdover, Bernd Weikl, is the finest Wolfram imaginable. Tatiana Troyanos is the voluptuous Venus, and Met newcomer Fritz Hubner offers an imposing if rather uneven Hermann.
Eva Marton sets the entire evening on a superb level with her electrifying Elisabeth, proving yet again that she is a splendid addition to the Met roster. Richard Cassilly is slated to sing Dec. 20 but was indisposed the night I attended. His alternate, Edward Sooter, revealed an ample voice in his first house try at the title role. He also showed some genuine style and tremendous promise.
This score has always brought out the very best in Mr. Levine. He makes ''Tannhauser'' a thing of visceral excitement and tremendous emotional intensity. His work is the icing on the cake of a grandiose Met-style show - the way the Met should be, rather than the ''Macbeth,'' which is the way it should never be.