Originally posted by bavd I did not say that these lenses are prone to failure, i meant they could not be converted to screw drive.
Rgds.
The goal would be to have lenses that don't need to be converted to screw drive. Unfortunately, the 16-50 and 50-135 seemed pretty prone to SDM failure. On the other hand, lenses like the DA *55 and DA 18-135 do not seem to have this predilection.
I don't find this thread particularly useful though. The problem is no one has numbers. What is the failure rate for screw driven lenses? What is the failure rate for in lens motors for each of the other lenses out there? How does that compare to other brands? Obviously there will always be some failures, but if the percentage is low, then that is probably acceptable. If ten or twenty percent of lenses are failing by the two year mark, then that is a problem.
I own ten year old copies of the 16-50 and 50-135 and both work fine, but my experience doesn't mean that there aren't plenty of folks out there who have experienced SDM failure. Without hard numbers you just don't know.