Quality control primes vs. zooms

I have the impression that there are more variation in quality between the samples of a lens if it is a zoom lens. I usually hear of bad copys when people are discussing zooms, seldom primes.
It this a fact? Is it easier to make a good prime than a good zoom?

Yes it's easier to make primes on the hole. It's not always easy to tell though if its bad copies or bad owners when complaints are made about lenses.

In general primes have fewer lens elements,fewer lens groups, and less shifting around of groups in operation, so they're much less susceptible to slight assembly errors.

Constant aperture zooms are difficult to make and they are mostly involved in QC issues.

In general... yes But take a look at the element counts in the super telephoto primes and DO lenses:

http://www.canon.co.uk​/Images/14_127385.pdf

foxbat wrote:
In general... yes But take a look at the element counts in the super telephoto primes and DO lenses:

http://www.canon.co.uk​/Images/14_127385.pdf

Then compare them to the equivalent constant-aperture super-tele zooms. Oh, wait, there aren't any. Note, too, that the various groups in zooms have to move around much more than the groups in primes do, and I did include the internal movements in the considerations.

First, there are many more zooms in circulation than primes, so the odds of somebody finding one that isn't as good is much greater.

Zooms have more moving parts, meaning more potential areas where optical alignment can be slightly off. Generally, primes only have moveable focusing groups (IS lens groups move as well, but that trait is common to both types of lenses).

Zooms, in general, are a compromise. They have to perform the work of several different prime focal lengths, sometimes with drastically different optical requirements. A wide-angle lens with a focal length shorter than that of the physical lens requires a much different optical correction than does a short telephoto with a focal length longer than the physical lens should provide. Put both of those requirements into a single zoom and you've got a very complicated package.

if you want the best optic's then its a Prime thats why i use primes and pay the price i have one zoom the 17 to 40L HOWEVER i have seen many shots with zoom's that i would have been proud to have taken, that guy on here with the sigmonster that take's birds is one of them that shows just what a zoom can do ( i hate him )
Rob