Canon 24-105 F4 date stamps

[skippy50]

I am daydreaming about buying a used Canon 24-105 F4 lens.  Any date codes that should be avoided? And where on the lens do I find the date code?

Any other tips for buying used gear over kijiji/craigslist?  I will only buy something I can check out in person before purchase.

[HickersonJasonC]

i would never buy a lens, new or used, without shooting it against another of the same type and comparing the results on screen. copy to copy lens quality varies hugely and doesn't necessarily follow any time frames. i bought a 70-200 f/4 is last year and while both were sharp, one was much sharper at the long end and the other was much sharper at the short end.

[stever]

i agree that the lens-lens tolerance variation with all lenses is more significant than particular production date - except with early production of new technology lenses like the Canon DOs.  i also think that later production lenses are generally better than earlier production but have minimal basis for this belief