Eye of the eclipse...

by darkhausen

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I've read a lot of reviews on sites like photozone.de, the-digital-picture.com and the likes and found that quite a few of their review samples turn out to be defective (including the premium 'L' lenses!) and they end up using as many as 4-5 lenses before getting a proper one. This makes me pretty paranoid when shopping for lenses.

I do understand that the higher defect rate on review sites could be due to the use of pre-production samples and\or initial production lots. Also, customer lens reviews on sites like Amazon seem to have lower defect rates. However, this could be due to general customers not being equipped to evaluate lens defects the way dedicated review sites can.

Is there any way to find out the reliability of a lens, and are there any defect rate or reliability charts for lenses? This is mainly to avoid known buggy lenses\production batches.

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This might be insightful: canonrumors.com/tech-articles/this-lens-is-soft-and-other-myths. I would agree that some defects might be due to the use of pre-production samples, however generally speaking I think its a combination of what the above article states, and a bit of pickieness on the part of reviewers...who tend to prefer their samples to be perfect, rather than simply acceptable. – jrista Nov 23 '11 at 17:30
There's an excellent article on this just up at dpreview: dpreview.com/articles/7333489584/variation-facts-and-fallacies/… – mattdm Nov 26 '11 at 3:57
In 30 years of photography, several dozens of lenses, I've encountered only 1 that was defective on delivery. That was a cheap zoom that arrived with a cracked barrel. – jwenting Jan 12 '12 at 6:40

1 Answer 1

The high reject rate for reviews tends to be down to them wanting a lens that is perfect for the test body they use. The tolerances for lenses and bodies can either add up to something unacceptable or cancel each other out. For instance if a lens is at one end of a tolerance limit and the camera body is also slightly out in the same direction this ends up with a poor result. However if the body is perfect or out in the other direction this will produce a good result. Same lens, just bad luck if you get a poor result. This why getting another copy of lens often provides a good result. Many higher end bodies now include micro adjustments for focus because this very often can correct for tolerance mismatches. Even the L lenses that I own apart from one all needed a bit of micro adjustment to get spot on focus.

This is not to say that all problems are down to this phenomenon, there are bad ones out there but high end lenses that are actually defective are quite rare and even many of these can be sorted out with calibration adjustments.

I suspect that almost all lenses leave the factory in a good state but after being thrown around by couriers can end up needing recalibration.

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more succinctly: the "reviewers" are pixel pokers who reject as defective perfectly functional lenses for no other reason than that they're not perfect. – jwenting Jan 12 '12 at 6:39

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