Approximately how far is optical infinity, in meters?

Approximately how far is optical infinity, in meters?

• A. 2 meters
• B. 6 meters
• C. 60 meters
• D. 0.6 meters

Answer: (B)

Optical infinity means the distance at which light rays entering the eye are effectively parallel, so the eye can form a clear image without changing its focus. In practice, the relaxed, unaccommodated state of the human eye occurs when objects are about 6 meters away (roughly 20 feet). At this distance the vergence reaching the eye is essentially zero, so no accommodation is needed. That’s why 6 meters is used as the standard approximation for optical infinity. Distances like 2 meters or 0.6 meters require the eye to accommodate to focus, and 60 meters is farther than needed to define the threshold, but 6 meters captures the practical point where focus becomes effortless.

Optical infinity means the distance at which light rays entering the eye are effectively parallel, so the eye can form a clear image without changing its focus. In practice, the relaxed, unaccommodated state of the human eye occurs when objects are about 6 meters away (roughly 20 feet). At this distance the vergence reaching the eye is essentially zero, so no accommodation is needed. That’s why 6 meters is used as the standard approximation for optical infinity. Distances like 2 meters or 0.6 meters require the eye to accommodate to focus, and 60 meters is farther than needed to define the threshold, but 6 meters captures the practical point where focus becomes effortless.