Maybe the life span depends on the quality of the lenses also. Like Canon L lenses have no problem after 15-20 years but the cheap EFs kit lens can survive few months only.
Your justification to compare L lens with non L lens is hilarious. L lenses are of course great, but cheap EFs are just as good.
erm.. i dont use canon.. but are u serious about ... Cheap EF kit lens only can survive a few mths?
my goodness.. u must be kidding... perhaps u need to explain more in detail...
No such thing as cheap EF lens can only last a few months. I mean, if Canon started making this type of lenses, then it is time the company folds up.
I have a 18-55mm kit lens (one of the cheapest around) and it last me for more than a few years now, I brought it to my China vacation shoot a thousands shot with it, and stuff it into my DIY camera bag, store it in overhead compartment of aircraft, whatever, and it survive all those ordeals.
I have a EF 50mm lens too, and it is the cheapest in Canon's line... also for a couple of years now, and it had been one of my favourite lens... up till now, no problem at all.
So all those bullshits on cheap EF lens that can only last a few months are just nothing but... bullshits.
Many folks thinks that mechanical parts do not fail so easily compared to electronics. It is only true to a certain extent.
Mechanical parts fail thru wear and tear, especially those plastic gear. Well lubricated metal parts can last helluva long time.
However, for electronic parts, it depends on how well it is designed and made. If the connectors start to corrode, or the chips are not properly sealed, over time, dust, moisture, oxidation etc would render it to fail.
For those who wanna to keep old lenses, it is a good idea to get it serviced once in a while, to get it cleaned up, lubricated and screws tightened.
I love big car, big house, big lenses, but small apertures.