unfocused said:
Awhile back I got curious, so I checked my customer profile on Adorama (they keep a record of everything you've ever ordered). Virtually every lens I've purchased is either now selling for more or roughly the same as what I paid.
So, I guess the answer would be: maybe never.
Untrue to one extent: Crap always varies. Good stuff on the other hand is on a "buy it if you need it" basis . . . because it's a hit-or-miss sale proposition.
The only lens I got (financially) burned on was the 70-300 IS . . . which is also the lens I was greatly disappointed in.
As I said in another post (paraphrased) it's not like X bursts into flames and stops taking good photos when it's replacement comes out.
Most people are looking for sales on the 24-70mm right now; so, just find a 'good' dip in price ASAP and stick with it, IF you need it and you'll be fine.