i am fairly new to this what i consider expensive L lens game but am more then willing to play as ihave already purchaed a few (how many and what not needed to know)... my question is this ...since my wife is beginning to think im nuts .. (could have bought her a new car she says) is there anything to the newer, IE two year old lenses being better IQ wise then say one 4-5 years old ... the reason i ask is simple ..i am getting tired of changing lenses so often and am considering a 100-400 but have the oportunity to purchase one built in 2005 for considerable savings... is that lens not as sharp as say a 2007 model ...because if that is actually the case then i will buy a new one .At this point the only zooms i own are a 10-22 and the 17-55 both canon of course. the rest (number and what not important..remember the car )are primes that cover that Fl and then some


opinions based on fact and experience much appreciated


mark