The giant Saturn S-IVB target vehicle seen during the closest approach of the first manned Apollo spacecraft, 11-22 October 1968

Vintage chromogenic print on matte fiber-based paper, printed 1968, numbered "NASA AS7-3-1536" (NASA MSC) in red in top margin, with "A KODAK PAPER" watermark on verso, 20,3 x 25,4 cm

The flight of Apollo 7 signaled the resumption of manned U.S. space flights 21 months after the Apollo 1 tragedy.
A major objective of the first Apollo crew to fly in space on board the newly designed Command Module was to rendezvous, without benefit of radar, with the second stage of their Saturn booster (SIVB).

The S-IVB remained attached to the CSM for about one-and-a-half orbits until separation. Schirra fired the CSM’s small rockets to pull 50 feet ahead of the S-IVB, then turned the spacecraft around to simulate rendezvous and docking, as would be necessary to extract a Lunar Module (LM) for future Moon landings. In the last mile, closing maneuvers were made by eyeballing the target. Here, the Spacecraft Lunar Module Adapter (SLA) on the rocket’s second stage opens like a giant flower during Apollo 7’s simulated docking. The round, white disc inside the open panels of the S-IVB is a simulated docking target similar to that used on the Lunar Module for docking during lunar missions. The distance between the Apollo 7 spacecraft and the S-IVB is approximately 50 feet. The view was taken over Texas at an altitude of about 125 nautical miles. Close-in maneuvering with the spacecraft, Eisele said later, was “rather like one car overtaking another, but a car with very weak brakes and not much acceleration” (Mason, p. 144).

From the mission transcript during closing-in maneuvering with the SIVB stage:

002:58:16 Stafford (Mission Control): Looks like you are looking at a four-jawed angry alligator. [referring to the Agena target vehicle he had encountered on his Gemini 9-A mission]
002:58:28 Schirra: It’s a bigger one, Tom. [Comm break.]
003:00:00 Public Affairs Officer (Mission Control): Apollo Control, Houston here. That is Walt Cunningham giving that report on the position of the SLA panels. He is in conversation with Tom Stafford who is an expert on angry alligators from the Gemini days. The crew is simulating a docking approach at this time in to the SLA area. They won’t go in so close as to touch it, but they will operate in the area. They are taking pictures and in general, they will fly a formation with the S-IVB for the next 10 to 15 minutes. [...]
003:09:18 Cunningham: There is quite a small type debris still inside the S-IVB. Is that Go? [Long pause.]
003:09:29 Stafford (Mission Control): Roger. Copied that.
003:09:31 Cunningham: Seems to be coming out. That’s probably the vent.
003:09:38 Stafford: Okay. [Long pause.]
003:10:32 Cunningham: All the internal structure looks just fine. There is one set of cords that’s running around - one set of cords running around that seems to be going to a panel that didn’t open too far.
003:10:48 Stafford: Okay. Get some pictures.

Literature:
The View from Space: American Astronaut Photography, 1962–1972, Schick and Van Haaften, pg. 48.