Norman Sperling. Originally published in The Refractor, vol. 73 #1, September 1996, p6.
Do people use their right eyes, or their left eyes, to observe through telescopes? If they predominantly use one, the design of telescope eyepiece areas might be specialized for that side.
On 5 public nights in March through July, 1996, tallies were kept of which eye was first used by members of the public who were observing celestial objects through telescopes at Chabot Observatory. The nights were selected for the following characteristics:
The sky was clear.
At least 30 members of the public were present
No other duties promised to distract from the tally.
In fact, answering questions from patrons did indeed distract from tallying approximately 10 observers. Also, fewer than 10% were noticed to try both eyes while at the telescope. Only the side first used was tallied.
Night Left Eye Right Eye
1 19 22
2 26 23
3 26 34
4 11 22
5 11 36
Total 93 137
Each side is used by large numbers of the public. Therefore, as expected, the design of eyepiece areas of telescopes for public viewing must accommodate both sides.