Dash Dash The dash is a punctuation mark that is similar in appearance to and , but differs from these symbols in both length and height. The most common versions of the dash are the en dash (–), equal to half the height of the font; the em dash (—), twice as long as the en dash; and the horizontal bar (―), whose length varies across typefaces. Historically, the names of en dash and em dash were loosely related to the width of a lower-case "n" and upper-case "M", respectively, in commonly used typefaces. Usage varies both within English and in
Looney 11 rule to a factor close to the square root of two, thus the above rule. The intensity of visible sunlight striking the surface of the Moon is essentially the same as at the surface of the Earth. The albedo of the Moon's surface material is lower (darker) than that of the earth's surface, and the Looney 11 rule increases exposure by one stop versus the Sunny 16 rule. Many photographers simply use the f/16-based Sunny 16 rule, unmodified, for lunar photographs. Looney 11 rule In lunar photography, the Looney 11 rule (also known as the Looney f/11 rule) is a method