Are there really such things as bad copies?

I know, I do it too. I hold my breath and with shaky hands I attach a virgin lens and take a test photo hoping that I got a "good copy" of my latest lens.

Canon is the world's leader in quality photography equipment. I'm sure they've got an outrageous team of engineers and top-notch manufacturing facilities. Do they really have "bad copies" of their best glass? Is there no quality assurance? Is it impossible to test for a bad copy in the lab? Do they have to send it to a customer and hope for the best? It just seems a little odd that of all the modern technology we purchase lenses are the only ones we worry about getting bad copies.

>>I'm sure they've got an outrageous team of engineers and top-notch manufacturing facilities

Incorrect. Competition to hire the best engineers is ruthless; just because they are a large company does not mean they have the best talent. And their manufacturing is behind the times. Due to recent poor company performance, they have put on hold the building of the new digital SLR plant they were planning in Japan that would've brought the manufacturing up to higher standards:

http://www.reuters.com …ews/idUSTRE50A0​IP20090111


>>Do they really have "bad copies" of their best glass? Is there no quality assurance?

Yes and yes. But think about this -- if you are selling a product to a consumer, you must include the hardware -- the glass, the metal, the focusing rings, the motors, etc. Those all cost money to produce and that is reflected in the price of the lens. Those things MUST be included. Now when you want to cut costs, what part of the production process can you eliminate or reduce and still deliver the lens? The Q/A of course.


>>Is it impossible to test for a bad copy in the lab? Do they have to send it to a customer and hope for the best?

"Within specifications" differs between the lines of lenses. So while it may seem soft to you, it may register as within specifications due to the lens or type of lens. Maybe only one in 10 lenses gets a rigorous test before it leaves the factory? (This seems more the case with Sigma, but I digress...)

And as I'm sure someone else will point out, most of the 'bad copy' syndrome on the forums is attributable to user error with misunderstanding of the depth of field from a larger-sensor'ed SLR, or too low of a shutter speed, or poor focusing technique, or a combination of the above.

Having worked some in high-tech manufacturing myself and from a limited knowledge of Statistical Quality Control, unless you are doing 100% testing, yes bad copies of anything can slip through.

Now, using POTN to calibrate the numbers is flawed because you have a disproportionately high number of very knowledgeable photographers. What many here would consider "soft" would be undectable to the average consumer.

Ignorance is bliss...

Even with the best quality assurance in the world, you should still expect a proportion of bad copies of anything. This is not limited to lenses but ALL technology. Computers, iPods, you name it, there are duds. And people worry about it all, not just lenses.

I don't know where you get the idea that of may be limited to lenses.

FlyingPhotog wrote in post #7075809
Having worked some in high-tech manufacturing myself and from a limited knowledge of Statistical Quality Control, unless you are doing 100% testing, yes bad copies of anything can slip through.

Now, using POTN to calibrate the numbers is flawed because you have a disproportionately high number of very knowledgeable photographers. What many here would consider "soft" would be undectable to the average consumer.

Ignorance is bliss...

I tend to agree with the latter statement. Speaking with many photo "enthusiasts", I have found that the notion of a "bad copy" is foreign to most. There must be quite a few subpar lenses out in circulation with the owner not realizing what they have. Most bad copies don't really show themselves unless used wide open...which probably eliminates a lot of lenses in the field and how they are used.

My co-worker just bought a brand new 50D w/ kit lens (28-135 IS i think?) over christmas. He brought it in right after the new year (vacations) because he was worried about the sound coming from the lens. Turns out he got a "defective" copy of the lens that sounded like a coffee grinder when IS was activated. On top of the sound the shaking through the eyepiece was completely unacceptable (it was enough to make you dizzy if you were shooting more than 2-3 photos).

Luckily BHPV was kind enough to swap it out for him without hassle but it was certainly an issue.

bohdank wrote in post #7075898
I tend to agree with the latter statement. Speaking with many photo "enthusiasts", I have found that the notion of a "bad copy" is foreign to most. There must be quite a few subpar lenses out in circulation with the owner not realizing what they have. Most bad copies don't really show themselves unless used wide open...which probably eliminates a lot of lenses in the field and how they are used.

Good point, I bet Green Box almost never chooses a wide-open aperture.

Aren't there really two different issues to discuss? The first is the one where an obviously bad copy is let loose on the market. These are the lenses that slipped through the QA/QC processes and release for general sale. These lenses are usually spotted by not only POTN members, but the general public as well as it's optical performance is clearly out of spec.

But there is a different class of lens. The ones that do pass QA/QC and are by all Canon standards a lens that could be sold. Yet to the enthusiast or finicky photographer the lens does not live up to expectations. These are much harder to detect and I believe lead to most of the "is this soft" discussion that happen here.

This is the one that strikes me most. I have had only one lens from Canon that I would consider a defective lens and a failure of the QA/QC program, but almost 50% of my lenses have had to go back to Canon as they were not living up to the quality I was expecting from the lens. Some of these lenses were returned to me with Canons note stating that the lens is within specs. A second call to Canon usually is needed to convince them that though the lens might be in spec, the quality is not acceptable. To Canon's credit, they work hard to get these types of issues ironed out.

mrkgoo wrote in post #7075826
Even with the best quality assurance in the world, you should still expect a proportion of bad copies of anything. This is not limited to lenses but ALL technology. Computers, iPods, you name it, there are duds. And people worry about it all, not just lenses.

I don't know where you get the idea that of may be limited to lenses.

I agree completely.

It certainly isn't limited to lenses. Look at the amount of so called 'friday afternoon' cars around. Those which are nothing but trouble from day one, because they have an unusually high amount of badly fitted components.

Even properly built cars have good and bad examples. Just like lenses they are built to be 'within specs', that can mean that your example may have 5% or more horsepower than your neighbours 'identical' model. Just as his lens may be a touch sharper than yours. Both cars and lenses are up to the required quality (within specs in other words) but performance varies a little. Common in most engineered products, I'm afraid.

I did not know that i had any bad copies until I read in this forum that they were bad

I think there are a lot more poorly skilled photographers than there are "poor" copies.

I agree; more bad photographers than bad copies. However...

Sometimes a photographer goes to a local shop, locks down his camera on a solid tripod, good lighting, low iso, MLU, multiple f-stops, etc. and shoots a series of blind shots matching a group of shots with a serial number and tests 4 copies of a lens side by side with careful control of the environment. Multiple identical shots, new focus acquisition each time for repeatability. He finds a very sharp copy, an OK copy and two dogs. Then he repeats the entire sequence, in a new order, new distance, blindly, and again finds 1 sharp, 1 OK and two poor copies. He then looks at the serial numbers and finds the performance in the first test matches, copy for copy, in the second test. He buys the sharpest copy. All else seems equal; color, contrast, saturation, noise, etc.

I believe the issue is more about the focus alignment, lens to body, than a copy that won't perform well at all. Perhaps another guy does the exact same tests on his camera body and finds one of the dogs now performs best, for him. I also believe that a lens can be shipped performing within spec but not spot on.

FlyingPhotog wrote in post #7075809
Having worked some in high-tech manufacturing myself and from a limited knowledge of Statistical Quality Control, unless you are doing 100% testing, yes bad copies of anything can slip through.

Now, using POTN to calibrate the numbers is flawed because you have a disproportionately high number of very knowledgeable photographers. What many here would consider "soft" would be undectable to the average consumer.

Ignorance is bliss...

that's it in a nutshell. many of the bad copies here just aren't and others are toward the edges of acceptable specs.

joe average consumer does not perform the POTN rectal exam on every lens he buys .

ed rader

Absolutely there are bad copies. They aren't nearly as common as these boards would have you believe, however. I had two consecutive bad Sigma 30s before getting my good one. By bad, I mean it would front focus by several FEET on anything over 6 feet away. My current one is stellar, though.

single_track wrote in post #7078963
...I believe the issue is more about the focus alignment, lens to body, than a copy that won't perform well at all. Perhaps another guy does the exact same tests on his camera body and finds one of the dogs now performs best, for him. I also believe that a lens can be shipped performing within spec but not spot on.

That certainly was the case of my 100-400. I was moderately happy with it on my XTi, but very disappointed with it on my 40. Both lens and camera took several vacations at Canon service and though Canon returned them both times claiming the lens and body to be within spec, I was never happy with it. When I upgraded to the 50D, I dialed in just a tad of micro adjustment and WOW did that lens pop. it was as it I was given a whole brand new lens and for the first time ever with that lens I understood why so many were raving about it. Thing is, it didn't need much adjusting at all.