Lenses - Good and bad copies
Discussion
A bit of a Devil's Advocate question, but whenever I read lens reviews on Fred Miranda or where-ever, reviewers invariably bang on about having a particularly good or bad copy of a given lens and having to return lenses numerous times until they get a "good copy".
I can well understand that half a century ago when optics were hand ground, the skill of the machinist was paramount in the quality of the end result and it might matter a great deal whether Hans or Herman made it - or if Franz had had one pilsner too many and his wife made him sleep on the sofa the night before. But today lenses are all made by CNC machines and subject to apparently legendary Japanese quality control.
I can understand that as with everything, sometimes things have manufacturing defects for a variety of reasons, but do manufacturers really allow lenses of variable quality to go out of the door as a matter of course ?
I'm very happy with all the modest but carefully purchased glass that's in my camera bag - but reading reviews of my lenses that make continuous reference to good and bad examples of what I've got - is making me a bit paranoid.
Is this a real issue or just Emporers New Clothes ?
I can well understand that half a century ago when optics were hand ground, the skill of the machinist was paramount in the quality of the end result and it might matter a great deal whether Hans or Herman made it - or if Franz had had one pilsner too many and his wife made him sleep on the sofa the night before. But today lenses are all made by CNC machines and subject to apparently legendary Japanese quality control.
I can understand that as with everything, sometimes things have manufacturing defects for a variety of reasons, but do manufacturers really allow lenses of variable quality to go out of the door as a matter of course ?
I'm very happy with all the modest but carefully purchased glass that's in my camera bag - but reading reviews of my lenses that make continuous reference to good and bad examples of what I've got - is making me a bit paranoid.
Is this a real issue or just Emporers New Clothes ?
Edited by Seight_Returns on Monday 13th July 12:30
I'm not sure, but there may be an aspect of lens/camera tuning at play. Fast lenses can demand a lot of AF systems - hence the fine tuning function in higher Nikons and some pros sending off body/lens combos to be calibrated individually. So it may just be that some camera's AF systems aren't accurate enough to work with very shallow DOFs, rather than the lens being 'bad'.
Mind you I did once try two Sigma 20-40mm lenses and they were both SO far out that they reminded me of this guy:
Mind you I did once try two Sigma 20-40mm lenses and they were both SO far out that they reminded me of this guy:
Amazingly, although the lens itself is machine made, many Canon lenses are still constructed by hand.
Oldish video, but I understand that is is still the current approach:
http://www.youtube.com/watch?v=KpkAWZTwqI4&fea...
Oh, and regardless of how well made, you have to factor in the "courier factor" of droppage in transit...
Oldish video, but I understand that is is still the current approach:
http://www.youtube.com/watch?v=KpkAWZTwqI4&fea...
Oh, and regardless of how well made, you have to factor in the "courier factor" of droppage in transit...
Edited by plg101 on Monday 13th July 13:41
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