Reprinted from yesterday's late editions.

Before the American musicals came the Viennese operettas and, more triumphantly than most, Franz Lehar's "The Merry Widow." Starting a series which will follow, in proper chronological order, with "Camelot" and "A Little Night Music," Shady Grove Tuesday night began a week's run of Lehar's old gem with Roberta Peters, a leading Metropolitan Opera soprano for years.

Fortunately, there are some other fine singers with Peters - Laurence Guittard, Harry Danner and Judith McCauley, as well as Werner Klemperer, the colonel of TV's "Hogan's Heroes" and Woody Romoff to handle what one might call "comedy."

European operetta style is as far from today's world as Mars, characters of royal and ambassadorial rank, a plot so silly as to blow the mind and humor that's downright painful. The style also demands scores of singers, dancers, violins and musicians, lavish settings and piles of red velvet.

Such you will not find in Shady Grove's arena stage, and some degree of patience is needed to get the hang of the outmoded fashion.Conductor Jonathan Dudley does what he can with a few strings among his dozen musicians.

Thus, the leading voices are vital, and, for this relief much thanks, they are good and well-trained. Peters shows the style and much of the voice which has kept her at the operatic top for a quarter-century. In a properly flashy wardrobe, she takes the firm stances sopranos have when getting into their big numbers. Her voice is at least carefully used.

Lehar's waltzy score includes not only "The Merry Widow Waltz," but also "Vilia," "Vienna, City of Dreams" and the Czardas Ethel Jackson once made famous in America. For Guittard there is the scampering "Maxim's" and for the fine full-throated tenor of Danner there are "A Virtuous Wife" and "Romance." McCauley, who played opposite Danner's "Student Prince" here, is a capable lyric soprano for Baron Popoff's flightly wife.

That name, Baron Popoff, should give a clue to the humor. He's an ambassador who encourages his wife to flirt with any man who takes a shine to the rich widow whose fortune is needed for Marsovia's treasury. As soon as the audience recognizes that "Hogan's" Klemperer is playing Popoff, the battle is won as far as it's possible to be won.

The Australian Ballet's dance version had the proper splash and personnel. Here what matters is the skilled singing for solos, duets, quintets and choruses: Lehar wrote some lovely tunes and elegant harmonies and those are what you will carry away.