Lenses used in tests
EF 24-105mm f/4L IS: Purchased new in 2006 and manufactured in April, 2006 (UU0404).
EF 24-70mm f/2.8L: Purchased new in 2004 and manufactured in 2004 (US0904).
EF 28-135mm f/3.5-5.6 IS: Purchased new in 2006 (date of manufacture is estimated as 2005-2006 since there is no date code on this consumer lens). This is the second sample of this lens I have owned which I purchased to compare with the EF 24-105mm lens as a travel lens with my EOS-5D.