An informal sampling of yesterday's sizable Kemper Open gallery, estimated at 30,000 and the biggest Friday crowd in the tournament's history, indicated fans care about the strength of the field, but not passionately enough to stay away when it's considered to be weak. Most seemed to care only moderately that they saw Greg Twiggs and not Greg Norman.

"I'm disappointed, but I'm still having a good time," said Danny Hill of Alexandria, taking a day off from his job as a policeman. "I usually pick out one player and follow him around, but the players I usually follow around are not here, {Fred} Couples and {Greg} Norman." Hill, at his eighth straight Kemper, said he intended to follow Tom Kite, Bobby Wadkins and Fred Funk yesterday.

"I am a lover of the game; I think I would have come no matter who showed up," said Leroy Sampson, an air transport worker stationed at Andrews Air Force Base. "I get to get up close to the players I idolize."

The Phil and Carol Cuellar family of White Plains, Md., picnicked near the practice green. "The field is a little weak, but they still have some outstanding players who can really shoot," said Phil. "We're going to follow Seve Ballesteros.

"Today is Friday, so we beat the weekend rush a little bit. We couldn't have picked a better day. Last year we enjoyed it and decided to come up again. It's nice and peaceful here. Nobody is pushing anybody around. I would have come out here regardless of the strength of the field."

General chairman Ben Brundred anticipated crowds of 40,000 each day this weekend, "if we get good weather." Yesterday's estimated crowd of 30,000 is more than last year's record second-round gate of 27,000. Funk Misses Cut

Thoroughly disgusted, Fred Funk shot a birdieless 74 for a 36-hole 145 and missed the cut by one shot.

A second year pro from Laurel, he could not make key putts. "That was the worst putting display I've ever seen," said Funk, who said he knew he had narrowly missed the cut before it became official.

He did hours of putting penance on the practice green Thursday evening after an opening-round 71. It did little good. He had numerous chances at birdies, about five or six opportunities from within 20 feet. The most telling was a six-footer that failed to fall on his 15th hole (the par-5 sixth).

"Oh, I had chances," said Funk, who has won $70,000 of his almost $82,000 in season earnings in the last month. "I missed them all." Still in the Running

Former Frederick pro Donnie Hammond hooked his shot into water on the 12th hole for bogey, but made four birdies, shot his second straight 70 and is in contention.

Hammond, who finished last year with a flourish, winning his second tour event, the Texas Open, and $458,741 for the year, has won $70,380 so far this year. . . .

Bethesda's Webb Heintzelman made three birdies on the front nine, cooled off on the back and finished with 71 and missed the cut. He started this tournament with a triple bogey, leading to an opening-round 76 that was too much to overcome. It's the second year he has missed the cut. Three years ago he tied for the first-round lead with 66.

"It is disappointing to play here for two years in a row like this when I know the course," said Heintzelman, who has had bone spurs and a pinched nerve in this his second season on the tour. Hurst, 20, Youngest

Amateur Jon Hurst, 20, formerly of Dumfries, was the youngest player in the field.

A former Washington area junior of the year, he shot even-par 71 yesterday but missed the cut after a balky putter left him with an opening 76. Still, he seemed satisfied with his performance in his first PGA Tour event, and hopes to someday be on tour.

"I feel pretty good," said Hurst, now married, living in Norfolk, and playing No. 1 for Old Dominion University. "I didn't embarrass myself. A couple of putts here and there and I'd be back for the weekend." . . .

The wheels came off for Middle Atlantic PGA pro John McNaney, and he had a mud-splattered white shirt to prove it. McNaney, who opened with even-par 71, visited water and mud on the sixth and seventh holes and finished with 78. . . .

It's back to the Woodmont pro shop for new head pro Bob Boyd after he soared to 79 yesterday after opening with 71. He started on the back nine and double-bogeyed the 12th and 18th holes to be out in four-over 39. Things didn't get any better on the front, with a double bogey at the second hole. He has a chance to redeem himself in Monday's U.S. Open sectional qualifying at his home course.