One the lens body near the rear lens element of most Canon lenses is a date code stamped on in the form of “UP0805”. This code is also present on many other Canon products such as camera bodies.
The first letter, “U”, is used to denote that the lens was made in Canon’s Utsunomiya, Japan factory location. For lenses manufactured before 1986, this letter is moved to the last position of the date code.
U = Utsunomiya,
Japan F = Fukushima,
Japan O = Oita, Japan
The next letter, “P”, is a year code that indicates the year of manufacture. Canon increases this letter each year starting with A in 1986 and prior to that, A in 1960 without the leading factory code. The following table is a quick reference for the year of manufacture:
A = 1986, 1960
B = 1987, 1961
C = 1988, 1962
D = 1989, 1963
E = 1990, 1964
F = 1991, 1965
G = 1992, 1966
H = 1993, 1967
I = 1994, 1968
J = 1995, 1969
K = 1996, 1970
L = 1997, 1972
M = 1998, 1973
N = 1999, 1974
O = 2000, 1975
P = 2001, 1976
Q = 2002, 1977
R = 2003, 1978
S = 2004, 1979
T = 2005, 1980
U = 2006, 1981
V = 2007, 1982
W = 2008, 1983
X = 2009, 1984
Y = 2010, 1985
Z = 2011, 1986
The first two numbers, “08”, is the month number the lens was manufactured in. Month 02 is February, month 08 is August. The leading zero of the month code is sometimes omitted. The next two numbers, “05”, are meaningless in determining how old a Canon lens is. This is a Canon internal code (that is occasionally omitted). This information will help you figure out when the lens was made. You would need other information to determine when the lens was first sold and used. Sometimes lenses may spend a long time on the shelf as inventory.
Forrás: http://www.the-digital-picture.com/Canon-Lenses/Canon-Lens-Aging.aspx
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