# The... horrible suspicion



## GP.Masserano (Feb 2, 2017)

Dear friends 
as everyone knows, the Canon lenses are built in many factories throughout Japan (and not only). 
The… *horrible suspicion* that affects all of us is the following: all the lenses that we buy regularly in the store or on Internet are qualitatively equal or there are series A+, A-, B, etc ?
We all know that there are minimal variations even in the same models of lenses , but (how often you can read for example on Photozone), not always the quality of the lens tested is excellent.
In my long photographic activity, for example, I found poor lenses (or below the usual standard), even of Leitz...

Have you ever experienced about defective Canon lenses or just below your expectations (Optical/mechanical) ?


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## AcutancePhotography (Feb 2, 2017)

Of course I have had bad experiences with lenses. Considering the number of lenses that Canon makes, even if their manufacturing quality was 99.99999%, that still leaves a considerable number of lenses that will "fall through the cracks". 

Which is the whole purpose behind warranted sales.

It has been my experience that most lenses, made by most manufacturers are mostly good most of the time. ;D


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## sanj (Feb 2, 2017)

Never experienced lenses worse than what they were meant to be.


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## YuengLinger (Feb 2, 2017)

GP.Masserano said:


> Dear friends
> as everyone knows, the Canon lenses are built in many factories throughout Japan (and not only).
> The… *horrible suspicion* that affects all of us is the following: all the lenses that we buy regularly in the store or on Internet are qualitatively equal or there are series A+, A-, B, etc ?
> We all know that there are minimal variations even in the same models of lenses , but (how often you can read for example on Photozone), not always the quality of the lens tested is excellent.
> ...



And just think about all the times lenses get dropped or left in hot trucks or cold trucks during delivery. I can't sleep at night!

Get a lens. Do some tests. Inspect. Take some pics. Nice? Keep. Not nice? Return.

Obsess if it brings joy.


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## AlanF (Feb 2, 2017)

Lensrentals has articles in their on the poor quality control from all manufacturers, e.g: "_The summary is almost all of you greatly overestimate the type and amount of optical testing that lenses get, whether it’s at the factory after assembly or in the repair center when it has a problem._" https://www.lensrentals.com/blog/2016/09/is-your-camera-really-the-best-optical-test/

They also regularly measure copy-to-copy variation, which can be very large; e.g. https://www.lensrentals.com/blog/2015/07/variance-measurement-for-35mm-slr-lenses/

The older 100-400mm f/5.6 had notoriously bad variation. The current 150-600mm from Tamron and Sigma are also very variable as seen from widely differing reviews. As in the last post, you have to test the copy you buy.


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## YuengLinger (Feb 2, 2017)

AlanF said:


> Lensrentals has articles in their on the poor quality control from all manufacturers, e.g: "_The summary is almost all of you greatly overestimate the type and amount of optical testing that lenses get, whether it’s at the factory after assembly or in the repair center when it has a problem._" https://www.lensrentals.com/blog/2016/09/is-your-camera-really-the-best-optical-test/
> 
> They also regularly measure copy-to-copy variation, which can be very large; e.g. https://www.lensrentals.com/blog/2015/07/variance-measurement-for-35mm-slr-lenses/
> 
> The older 100-400mm f/5.6 had notoriously bad variation. The current 150-600mm from Tamron and Sigma are also very variable as seen from widely differing reviews. As in the last post, you have to test the copy you buy.



Good reminder, AlanF. We all like to imagine lens factories as cathedrals of quality control, with each assembly line worker, in spotless lab coats, attentively, faithfully shepherding each new lens through the stages of production.

I've never visited a lens factory, but I'm told they are...heavenly. :


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## dak723 (Feb 2, 2017)

I have never had a defective lens, but as others mention, there is always some variation in quality. In most cases, if you don't pixel peep, you won't notice. Some variation in quality is true of virtually everything that is manufactured. That's why they have returns. If you aren't happy with your copy, return it for another. It's not a "horrible suspicion." It's not a conspiracy. It's reality.


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## GP.Masserano (Feb 2, 2017)

dak723 said:


> I have never had a defective lens, but as others mention, there is always some variation in quality. In most cases, if you don't pixel peep, you won't notice. Some variation in quality is true of virtually everything that is manufactured. That's why they have returns. If you aren't happy with your copy, return it for another. It's not a "horrible suspicion." It's not a conspiracy. It's reality.




I *never* said that there was a "conspiracy" but only the legitimate suspicions that some specimens of a certain lens is not entirely satisfactory (beyond the normal and acceptable variations in production).
Or that some nations of the world are privileged to encourage massive volumes of purchase.
For example, in Italy everyone knows that richest of accessories and equipped cars FIAT are exported to abroad, precisely to encourage purchase in "strong markets"...
Nothing outrageous: simple "market" rules...


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## 7DmkI (Feb 2, 2017)

Just wanted to share a quality issue and buying experience a few years ago…

Went into a camera store to buy a 24-70 F4L which was on sale. The salesman took one out and I looked at it; it had a noticeable white stuff inside the lens, the salesman looked at it and agreed there was something inside. Asked them if they have another one, the answer was no but could order in a new one. Another salesman overheard it and said “the dust won’t affect the IQ”. I said I’ll wait for next one. Two days later, got a call, went to the store, examine the “new” lens, same thing – a white dot inside the lens. I asked if they had given me the same one and of course the answer was no. They could order me a third one and I could take down the serial number of the defective ones to ensure they were not the same. I said I’ll pass and would get it from another retailer. Then the other salesman came by and said “the dust won’t affect the IQ; the lens was not made and/or use in air tight condition and would have dust inside sooner or later.” My answer to him was if you went to buy a new car, there was a noticeable dent or scratch on it, it would not affect the performance, safety etc; will you take it?” Silence. I walked out the store.


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## monkey44 (Feb 2, 2017)

After buying several refurbished cameras and lenses from the Canon store, we've noticed a remarkable level of very good products. I most often buy new because if I need or want a lens, then I buy pretty much at release or shortly after.

But, I bought a 7D and wife a 60D and a few lenses. We've never had to return or adjust any of them, and they seem to operate and focus spot on.

Although it's a minuscule sample (about six) it may give a tiny bit of evidence that the refurbished stock is given a very thorough vetting before it's re-stocked. Just an opinion, nothing scientific or data specific. But it may at the same time, indicate production run inspections are less intense. Then, maybe not??


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## neuroanatomist (Feb 2, 2017)

AlanF said:


> Lensrentals has articles in their on the poor quality control from all manufacturers...



I think most people simply don't understand the point of quality control (QC). People seem to think 'good QC' means every product that leaves the factory is perfect, or that the point of QC is to achieve the highest quality possible. Conversely, 'poor QC' means lots of variation between products, a high failure rate, etc.

Wrong. 

The point of QC is to ensure that production is meeting the standards the company has pre-defined for quality. Good QC means the production meets those standards, poor QC means it's failing to meet those standards. Higher standards mean higher cost to maintain them, so a company may set lower standards but meet them perfectly – that's good QC. Perfection is prohibitively expensive. Particularly where the product is evaluated subjectively by customers, lower standards may be acceptable. So, for example, it would be quite reasonable to have high standards for AF motor performance becuase if the AF stops working, customers will know...but have lower standards for optical performance becuase a majority of customers will not really know if their lens is a little less sharp than it could be.


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## AJ (Feb 2, 2017)

Yes I've had a EF-S 17-55 that was unusable at 35 mm (I returned it, got a better copy). My friend had a 70-200/4 L that was very badly decentered (repaired by Canon)


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## Mt Spokane Photography (Feb 2, 2017)

The Japanese do not use QC, but 6 Sigma QA which is much more demanding than QC. QC samples lenses off the production line, and verifies that "X" percent meet standards, usually 2-5% are allowed to be out of specification. That practice has long long ago been abandoned by Japanese manufacturers and most others major manufacturers.

Six Sigma processes inspect every lens. They are inspected by the assemblers at defined steps during manufacturing and assembly, and every finished lens is tested. There is variation, of course, tha'ts where the 6 Sigma name comes in.

" A six sigma process is one in which 99.99966% of all opportunities to produce some feature of a part are statistically expected to be free of defects (3.4 defective features per million opportunities). "

But ...assuming every lens leaves the factory perfect, how many would arrive in the same condition, considering the transportation process which is entirely out of Canon's hands. 

There is no 6 Sigma in transportation, containers of products get banged around loading and unloading from ships, while being moved on trucks and trains, pallets get dropped by forklifts, then lenses are transferred to pallets in boxes for shipping to retailers, and get more rough handling. Within a large retailer, they can be subjected to dropping and spearing with forklifts, and then, from the retailer to the consumer, by UPS , FedEx, etc, they get extremely rough handling.

I believe that when a decentered lens is received, the odds are that it left the factory in perfect condition.

Have you noticed Roger Cicalas tear-downs of the newer "L" lenses, they are being built much more robust, I suspect that's mainly due to Canons recognition of the cost due to failures during shipping. The last new lens I bought (100-400mm L II) was packed much better than older lenses were, again a sign that Canon recognizes the problems during transportation.

And, of course, Roger has published articles about how many lenses of his are damaged in transportation. That's why they do a 100% inspection, yet, customers receive bad lenses.


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## Viggo (Feb 2, 2017)

The worst offenders I have had are the 35 f1.4 L and the 135 f2.0 L. I have had a bunch of copies of a lot of lenses and those two are the most variable I have come across, some copies are completely stellar and it's either that or quite poor.

The 24 L II comes in second with three copies owned, all brand new, all with unreliable AF.

Other than that I have found all the lenses bought and sold (close to a hundredandfifty in total) were highly consistent between copies. And most have met my expectations.


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## AlanF (Feb 2, 2017)

This is a very good article by Roger Cicala about what really happens in QA and what it means and could cost.
https://www.lensrentals.com/blog/2016/02/optical-quality-assurance/


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## Mt Spokane Photography (Feb 2, 2017)

AlanF said:


> This is a very good article by Roger Cicala about what really happens in QA and what it means and could cost.
> https://www.lensrentals.com/blog/2016/02/optical-quality-assurance/



I've worked with dozens of companies as they switched over to six sigma processes. First, they groaned at the requirement, later, they were all smiles because their bottom line improved due to eliminating costly rework or returns. A explanation of the 6 sigma process is long and can be hard to understand.

Very simply, process control starts with designing a product so it can be properly manufactured, that's obvious. 

Then, a group of experts, usually in design, define the key characteristics for each part / process. Perhaps the purity of the silica that goes into the glass is key, if so, that is identified, same for the crystal growing process.

Then, quality assurance, procurement, and manufacturing determine how to achieve those key characteristics. Perhaps each batch of glass may be checked for its key characteristic. As each lens element is ground and polished, the final piece may be checked and graded, even put into different bins if values are critical. Then, as lens groups are built up, pieces with a higher or lower value can balance out others so a final cemented assembly is within tolerance. That's how a manufacturing process goes for the high end $$$ $$ value lenses made in Japanese factories. Its why the lens costs are so high. Each part of the process that is a key is checked along the way. This saves a ton of money, testing a lens at the end of the process and finding that some unknown internal element is off, can cost far more to rework it than doing it right. 

Now, for cheap consumer lenses that cost a manufacturer $10 to churn out will just be tossed if they are bad, don't expect them to have little variance, the tolerances are wider, its related to the price. There are many trades that go into hitting a target cost.

There are a series of Canon videos that outline the lens manufacturing process for high end lenses. They don't show any proprietary things, but give a good feeling for the many steps and checks in the process.

https://www.youtube.com/watch?v=OkWsk9rXpcU

https://www.youtube.com/watch?v=7T7BDeMU_Ks&spfreload=10

https://www.youtube.com/watch?v=KpkAWZTwqI4&spfreload=10


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## AlanF (Feb 2, 2017)

Your middle paragraph about putting compensating parts together is a 19th C US invention. As you know, mechanical watches have jewelled bearings for metal shafts. Making the holes in the rubies to be the same size as the diameter of the shafts was an expensive process. But, the Waltham Watch Co had an amazing idea: make a batch of the shafts, and they would have the usual degree of variation, drill a batch of the rubies, and they would have the same degree of variation, then sort them and fit the narrow shafts to the rubies with small holes and so on.

The Americans taught the Japanese QA after WWII, and the Japanese haven't looked back.


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## Boyer U. Klum-Cey (Feb 2, 2017)

Canon's 6 Sigma approach has worked for me so far. Only blot was a 7D II that had to go back 3 times(w/ Canon paying the postage) to get it right. CSat score very high for moi!


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## TexPhoto (Feb 2, 2017)

I recall a "pro" explaining in a blog, that he would go to a big camera store like B&H and buy 3-5 of a new lens, test them, select the best one and return the others. I was mildly horrified as I realized Oh, I am ordering online and at best can hope to receive on of the 4 he gave back. This was maybe 10 years ago. He explained that because he was a frequent customer, paid retail, etc, the store was OK with this.

I have to say i have been generally very happy with the gear I receive.


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## Bennymiata (Feb 2, 2017)

I've never had a problem with Canon lenses (except for a 50mm 1.8) but I recently bought a Tamron 85mm 1.8 and thought I got a dud.
I amfa'd it on a tripod and it still wasn't focussing correctly, then decided to amfa it hand held (as that's how it's going to be used), and after around 30 minutes of fiddling, it now focusses very well.

Sometimes you need to make adjustments in different ways to get a lens to play nicely.


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## AlanF (Feb 2, 2017)

Bennymiata said:


> I've never had a problem with Canon lenses (except for a 50mm 1.8) but I recently bought a Tamron 85mm 1.8 and thought I got a dud.
> I amfa'd it on a tripod and it still wasn't focussing correctly, then decided to amfa it hand held (as that's how it's going to be used), and after around 30 minutes of fiddling, it now focusses very well.
> 
> Sometimes you need to make adjustments in different ways to get a lens to play nicely.



You could get a steady job as a human tripod.


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## GP.Masserano (Feb 3, 2017)

Many thanks for your answers. 
Can you explain (In extreme synthesis) what is the 6 SIGMA QA process that you have mentioned in many topic?


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## mackguyver (Feb 3, 2017)

GP.Masserano said:


> Many thanks for your answers.
> Can you explain (In extreme synthesis) what is the 6 SIGMA QA process that you have mentioned in many topic?


It's something I work in as well, and the simplest way to explain it is that you're targeting 99.99966% of whatever you make or do to be within specifications (i.e. not defective). That's 3.4 defects per million lenses (or bank transactions, email transmissions, etc.). The key is in have reliable ways to measure the product (lens in this case) is within specifications, detect when it is not, and better yet, engineering it up front so that the product is within specs 99.99966% of the time. Getting there is pretty complicated, but that's what the goal of Six Sigma is in essence.

One area where you will have noticed the impact of Six Sigma is in the thickness of aluminum cans and plastic water bottles. By engineering much better quality into the manufacturing, they have been able to reduce the specification (range of acceptable thicknesses) to the point where they can consistently make them near what used to be the lower limit (thinnest measurement of thickness). Thus, bottles are much thinner and by using less plastic while still having a strong enough bottle, they are saving millions each year. Too bad they don't pass on the savings, right? 

For lenses, it means that whatever range of quality they have deemed acceptable for each lens can be manufactured more reliably and saving them money by having less lenses that don't meet spec and must be recycled/remanufactured. For us, that means that their newest lenses, no matter the price, are going to be more consistent than their older lenses, because those lines are still in use, but likely haven't been modernized with Six Sigma or other processes to improve quality/consistency. Lensrentals has noted that about the newer Canon lenses.


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## C4userguy (Feb 13, 2017)

Mt Spokane Photography said:


> The Japanese do not use QC, but 6 Sigma QA which is much more demanding than QC. QC samples lenses off the production line, and verifies that "X" percent meet standards, usually 2-5% are allowed to be out of specification. That practice has long long ago been abandoned by Japanese manufacturers and most others major manufacturers.
> 
> Six Sigma processes inspect every lens. They are inspected by the assemblers at defined steps during manufacturing and assembly, and every finished lens is tested. There is variation, of course, tha'ts where the 6 Sigma name comes in.
> 
> ...



I don't even know where to start with this post.


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## AcutancePhotography (Feb 13, 2017)

C4userguy said:


> I don't even know where to start with this post.



Then maybe you should give it some thought and decide what you want to write before you post a reply?


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## Zeidora (Mar 9, 2017)

sigma = statistical standard deviation. 2 sigma (precisely 1.96 for larger number of observations, usually taken as >>100, but usually rounded to 2 for ease and good measure) is the 95% confidence interval. 6 sigmas is way further our on the bell curve. As Mt spokane pointed out, 99.99966% confidence interval. Haven't checked, but sounds about right. 

Standard deviation = Square root of sum of squared deviations from mean divided by number of observations minus one.

hope that helps. If not, google standard deviation in statistics.


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