On 5 Mar 2003 12:57:21 -0600, rmonagha@smu.edu (Robert Monaghan) wrote:

[...]

>the http://medfmt.8k.com/third/variations.html pages address your concern

>about variation within batches of lenses; they can be quite large, even

>with new in the box lenses, and even more so with used lenses. My own

>belief based on these examples is that there is more variation within a

>batch of lenses than between similar type and priced lenses. In the

>example in this thread, the averages were only .1 or .2 out of 5 units

>apart. My bet is that the variation within many of the lens groups is more

>like 1/2 unit or larger. The test of new in box Kowa lenses from the same

>batch is pretty amazing, given the large variation shown. The general

>belief that all lenses are identical as peas in a pod is clearly wrong.

>This also explains why some people rave about a particular lens, and

>others dismiss it or have bad experiences - the lenses may well have been

>the better and the worst examples of that lens type, so both reviewers are

>right ;-)

[...]

My experience is that for the better lines (and also

for those that use automated "short-cut" manufacturing

methods, often resulting in good consistency), most of

the output for a given lens (with notable exceptions)

falls within a fairly closr range of variation, with the

occasional exception existing - so for the most part,

the experience with one lens compared with a different

lens is fairly valid... In my Nikkor list, I do try to

give the variation I've seen, which is great for only

a few lenses - and for most of these, the variation is

not evenly distributed between the best and the worst

(most of the samples perform close to the best...). The

Nikkor list is at www.David-Ruether-Photography.com/slemn.html.