Plunging into the fast-growing home video marketplace, Eastman Kodak Co., the world's largest photography company, introduced yesterday a one-piece "camcorder" that combines a video camera and recorder based on a new 8mm videotape technology.

However, Kodak is not manufacturing the new video system itself. The company said the camcorder was being manufactured to specifications by Matsushita, the giant consumer electronics company that also manufactures VHS video cassette recorders (VCRs) under the name Panasonic, while the tapes and cassettes will be made by TDK, another Japanese company.

General Electric Co., meanwhile, announced yesterday that it would introduce a similar product this weekend at the semi-annual consumer electronics show.

Home video has been one of the most robust segments of the consumer electronics industry in the last five years. Several experts project that more than 8 million VCRs will be in American households by 1985. In the first 51 weeks of 1983, more than 3.9 million VCRs were sold, representing a 101 percent increase over 1982 sales.

Moreover, sales of color home video cameras have closely tracked the growing sales of portable VCRs, with nearly half a million cameras sold in 1983--roughly a 40 percent increase over the preceding year.

The Kodak camcorder approach is designed to blend the best of both markets and offer consumers an entire home video system for under $2,000. The cordless, five-pound device would let users tape a sequence and then play it back by attaching the unit to a television set--thus eliminating the need for a separate VCR playback unit.

The home video market is currently dominated by the Japanese consumer electronics companies that produce the equipment in two video formats--Beta and VHS. VHS VCRs outnumber Beta recorders by more than 3 to 1.

The Kodak move to offer an 8mm technology reflects an effort to create a third standard for home video equipment. One advantage of the new format is that it permits lighter and less bulky equipment; the Kodak tape is roughly half the size of the conventional half-inch tapes now used in most home video products.

However, Kodak will also market a new line of Beta and VHS half-inch video cassettes. Prices for the new line have not been disclosed.

"Kodak is a changing company," said Michael Ellmann, a research analyst with Wertheim & Co. in New York. "They're looking into new products. This is an experimental program for the company and it will test the power of its distributional ability."

Ellmann points out that Kodak is "the last holdout" of the conventional photography companies not directly involved in the home video market. Both Polaroid and Fuji Film Co., the Japanese photography company, currently offer a line of home video tape products.

Shipments of the new system are expected to begin this summer.

In a related move, RCA Corp. introduced a palm-size color video camera weighing under three pounds that will retail for under $1,000. The company said the camera will be sold nationally later this month.