And the 45-150 goes back...

Started Nov 11, 2012 | Discussions thread
carlosvp
Regular MemberPosts: 193
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Re: And the 45-150 goes back...
In reply to ryan2007, Nov 12, 2012

ryan2007 wrote:

I never understood when anyone says they have a bad copy. To me if you have a bad copy then the original one is bad because that is the mold or blueprint OR all the ones after yours are bad

Actually, that's just not the case.  Lens manufacturing requires a lot of precision calibration of lens elements for positioning - there's all kinds of adjustments that are done to each element or group as they're put together.  And one element or group being off-center, tilted, or slightly too near or too far can make a huge difference in the image quality that results.  We're talking precisions of fractions of a millimeter here.

A good illustration of copy-to-copy variation in lenses is here:

http://www.lensrentals.com/blog/2012/11/canon-24-70-mk-ii-variation

If you read that blog, you'll see some articles about specific examples of image degradation due to misalignment of lens elements, too.

C.

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