File:AS08-12-2100 - Apollo 8 - Apollo 8 Mission image, Farside of Moon - NARA - 16668703.jpg

• Scope and content: The original database describes this as:

Description: Apollo 8,Farside of Moon. Image taken on Revolution 4. Latitude 12 South, Longitude 157 East. Camera Tilt Mode: Vertical Stereo. Sun Angle: 51.5. Original Film Magazine was labeled D. Camera Data: 70mm Hasselblad. Lens: 80mm; F-Stop: F/8; Shutter Speed: 1/250 second. Film Type: Kodak SO-3400 Black and White,ASA 40. Other Photographic Coverage: Lunar Orbiter 1 (LO I) S-9, Lunar Orbiter 2 (LO II) S-3,S-5. Flight Date: December 21-27,1968.

Subject Terms: Apollo 8 Flight, Lunar Photography

Categories: Lunar Observations

Original: Film - 70MM B&W

Interior_Exterior: Exterior

Ground_Orbit: On-orbit

This photo was used in Figure 2-6 (b) of the Analysis of Apollo 8 Photography and Visual Observations (SP-201), which has the following caption:

Comparison of photography of same area (13° S, 157° E) on the lunar far side. (a) Portion of Lunar Orbiter II frame H-75 (Sun angle 19°); (b) Apollo 8 frame 2100-D (Sun angle 51.5°).

The text of the Analysis refers to the figure as follows:

One of the most important aspects of the Apollo 8 photography is the acquisition of high-resolution photographs under high-illumination conditions. For the first time, it is possible to compare topographic features photographed by Lunar Orbiter under relatively low lighting conditions (phase angle of approximately 20°) with the same features photographed by Apollo 8 under high lighting conditions (phase angles greater than or equal to 50°) and with approximately the same resolution.

Figures 2-5 to 2-8 are pairs of Lunar Orbiter and Apollo 8 photographs of the same areas taken under different lighting conditions. The Lunar Orbiter photographs were all taken at a relatively constant Sun angle of approximately 20° from the horizontal, while the Apollo 8 frames record Sun angles varying from 34° to 77°. As the Sun angle becomes greater, differences in albedo become more apparent. On the Apollo 8 photograph in figure 2-5(b), albedo differences are just beginning to appear at a phase angle of 34°, and it is still easy to recognize topographic features by their shadows. At the higher phase angles (51°, 62°, and 77°), shown respectively in figures 2-6(b), 2-7(b), and 2-8(b), the albedo differences are readily apparent; but it becomes considerably more difficult to recognize elevation differences because of the lack of shadows.