Originally posted by Edgar_in_Indy If the difference in price between new and used was greater, I might consider a used one, but $150 is not even close to being enough of a difference.
I agree that the price gap between the two needs to be big enough to justify buying a used lens over a new lens. How big that gap needs to be depends on a lot of factors. For me, if I am purchasing a DA* lens, the gap needs to be large enough to cover the cost of placing the SDM motor. So basically a $150-200 gap is about right (for me). I personally would prefer a used lens and $150 because I believe it puts you in a better position overall as one of three things will happen. Let's say the lens fails in the first year, you use the money to buy a new SDM motor and you're no worse off than had you bought it new. Let's say the lens fails outside the first year, well now you're better off because you use that $150 in savings to replace the motor and you're $150 up on where you'd be had you bought a new one and it failed outside the 1 year warranty period. Or the third case, let's say you don't end up with a failure during the time you own the lens. Well in that case you end up with an extra $150 in your pocket. Obviously the above doesn't account for the slim possibility that the lens fails twice (which I realize can and has happened on occasion). That said, I still think the postivies outweight the small chance of a double failure.
Now, if you buy the lens new AND choose to buy an extended warranty, then the numbers change a bit. Depending on how likely you think the SDM motor is to fail during the time of your extended warranty, and how much the warranty costs, will dictate whether it is worthwhile compared to buying used.
Anyway, I know my opinion on the matter is typically not a popular one as the convenstional wisdom is to only buy DA* lenses new because of the higher than expected rate of SDM failure. While I understand the motivation behind that notion, generally speaking, the math doesn't usually support it.