Quality control issues with the 24-70 L II?

Status
Not open for further replies.
Sort by date Sort by votes
H

heptagon

Jun 25, 2012
227
0
6,286
#1
These two lenses should look exactly the same:
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=787&Camera=453&Sample=0&FLI=4&API=0&LensComp=787&CameraComp=453&SampleComp=1&FLIComp=4&APIComp=0

At the short end one is better, at the long end the other. But why? They should both look best for all focal lengths and never have passed the quality control.

Maybe the optical design has such low tolerances that Canon can't make it work properly and this was the reason for the long delays.
 
#3
Invertalon said:
I find one of the samples fishy to be honest. Take a look at this:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=787&Camera=453&Sample=1&FLI=2&API=0&LensComp=787&CameraComp=453&SampleComp=1&FLIComp=2&APIComp=2

Same lens, same focal length, one a stop down from the other. The f/4 should be sharper. Why is it so soft compared to f/2.8?

Something seems off.
Click to expand...

I have to say that I've long said that my results often don't match what TDP gets. Lens testing is really, reallly tricky. You have to be so careful and take many repeated attempts at each shot and then picking the best from that. I've done it a few times and it kinda drives you crazy. I have noticed some odd things on other lenses, like you say, where it will look like an 8 wide open and then suddenly like a 6 the next stop down and then back to an 8 the next stop and then to a 9. Doesn't make sense. Seems like bungled focusing to me.

It's also weird that every single tamron lens they test does horribly. Why? All three tamrons that I have owned have done much better.

That said, there can be copy variation.
 
Upvote 0
#4
heptagon said:
At the short end one is better, at the long end the other. But why? They should both look best for all focal lengths and never have passed the quality control.
Click to expand...

Maybe a good idea not to get a lens from the first batch - given the high demand and high revenue they'll probably sell every lens they've got and lower the qc standards accordingly?

Concerning tdp: The soft lens @70mm certainly shouldn't have been sold, @24mm I cannot see that much of a difference - lesson learned: paying $2000+ for a lens doesn't give you the certainty to have a perfect lens.

The same thing occurs on their 70-300L samples, I was very insecure how to manage to get a "good" copy, but the unfortunate truth is that it's near impossible to tell for a laymen w/o specialized equipment. The only thing you can do is to match the long end of the 24-70 against a known good copy of a 70-200.
 
Upvote 0
#6
Marsu42 said:
heptagon said:
At the short end one is better, at the long end the other. But why? They should both look best for all focal lengths and never have passed the quality control.
Click to expand...

Maybe a good idea not to get a lens from the first batch - given the high demand and high revenue they'll probably sell every lens they've got and lower the qc standards accordingly?

Concerning tdp: The soft lens @70mm certainly shouldn't have been sold, @24mm I cannot see that much of a difference - lesson learned: paying $2000+ for a lens doesn't give you the certainty to have a perfect lens.

The same thing occurs on their 70-300L samples, I was very insecure how to manage to get a "good" copy, but the unfortunate truth is that it's near impossible to tell for a laymen w/o specialized equipment. The only thing you can do is to match the long end of the 24-70 against a known good copy of a 70-200.
Click to expand...

Companies don't lower QC standards. They are written in company SOP and followed like a recipe word for word. That doesn't make any sense at all. Have you ever worked in a QC department?
 
Upvote 0
#7
bdunbar79 said:
Companies don't lower QC standards. They are written in company SOP and followed like a recipe word for word. That doesn't make any sense at all. Have you ever worked in a QC department?
Click to expand...

No, I did not. But I wonder how you can say with absolute determination that qc standards are never lowered no matter what the company or market situation is, nowhere, globally. That doesn't make sense to me, if I may say so. But it might very well be that my speculation is wrong and the first samples of 24-70ii will be just like the ones later on.
 
Upvote 0
#8
Marsu42 said:
bdunbar79 said:
Companies don't lower QC standards. They are written in company SOP and followed like a recipe word for word. That doesn't make any sense at all. Have you ever worked in a QC department?
Click to expand...

No, I did not. But I wonder how you can say with absolute determination that qc standards are never lowered no matter what the company or market situation is, nowhere, globally. That doesn't make sense to me, if I may say so. But it might very well be that my speculation is wrong and the first samples of 24-70ii will be just like the ones later on.
Click to expand...

Well, no, I can't do that. However, for a company as big as Canon, it would be unrealistic that they could take the time to purposefully lower QC standards when they are so large and handle so many manufacturing units. You'd be surprised at how robotic some of these people are doing the QC testing according to SOP. We used to joke that a monkey could do it and all you had to do was feed it peanuts every so often. No offense to QC personnel.
 
Upvote 0
#9
BDunbar is correct here. It takes many years for a manufacturer to establish good quality control procedures.

You don't change those for the worse, if there is no pressing need to do so and Canon is certainly not a company near bankruptcy, so that cost reductions in quality control may become necessary just to be able to manage cash flow.
 
Upvote 0
#11
Quality standards are not reduced over time, but the number of units getting a major inspection off the line can decrease. In order to maintain efficient throughput in manufacturing, not all aspects of the assembly are inspected at 100%. Rather, random sampling is done at various points on the line to try and establish a confidence level in the units being built. Normally, during the first builds, Acceptable Quality Level (AQL) values tend to be stringent so that inspection sample sizes may be larger, and this is done so that the confidence level is greater for an acceptable number of units. If the inspections on those sample sizes falls within the acceptable range with an acceptable deviation from the nominal, inspection sample sizes may get smaller over time due to a reduced AQL on a well-established procedure.

I'm sure there is a standard final quality assurance procedure that is done 100% as the final step, but it is probably not as detailed as a complete inspection based on the AQL sampling of a manufacturing lot. The same also applies to the components in a lens (e.g. optic components, lens housing, etc). So, it's completely believable that there is some unit-to-unit variation since not all components are inspected at a 100% level (a lot of validation and six-sigma work is probably done in parallel to nail down the process for the manufacturing of the components too).
 
Upvote 0
#12
Deja-Vu all over again, just like the 24-70 mark 1, everyone will be talking about whether there's is a 'soft' or 'good' copy :o

Having said that, according to the digital picture tests in the previous links, the 70mm @ 2.8 looks about the same as the 24mm @ 5.6

QC is all about tolerances - not every product has to be 100%, so 99% = "QC Passed"

Then there is the LensRental argument that both bodies and lenses have tolerances, so AFMA becomes an imperative...and so on
 
Upvote 0
#14
Could the AF have been off on the soft sample? I noticed the 24-70 II I used was backfocusing slightly.

Also, I wouldn't always trust their test results. Some of the Zeiss lenses they have on there have terrible test results but when I've used them they were absolutely amazing.
 
Upvote 0
#16
Invertalon said:
Anybody know if they focus via live-view for these tests (I would hope so)? It would be weird relying on the AF of the camera, so I am 99% sure they do use live-view.
Click to expand...

From TDP:

"Tests are conducted using externally-magnified Live View manual focusing and center-point-only autofocus. The best of the many re-focused shots (typically at least 10 sets - often 15-20) are used for the results for each camera/lens/focal-length/aperture combination. The proper lens hood is in place for all test shots, all filters are removed. Image Stabilization, if available, is turned off."
 
Upvote 0
#17
neuroanatomist said:
Invertalon said:
Anybody know if they focus via live-view for these tests (I would hope so)? It would be weird relying on the AF of the camera, so I am 99% sure they do use live-view.
Click to expand...

From TDP:

"Tests are conducted using externally-magnified Live View manual focusing and center-point-only autofocus. The best of the many re-focused shots (typically at least 10 sets - often 15-20) are used for the results for each camera/lens/focal-length/aperture combination. The proper lens hood is in place for all test shots, all filters are removed. Image Stabilization, if available, is turned off."
Click to expand...

Keep in note:

1. they did not do that on their earlier tests, they were much less careful earlier on
2. despite the above they still get weird things some apertures suddenly going to junk, maybe it's just mixed up files now and then, but for some reason they seem to only ever get bad copies of tamron
 
Upvote 0
#18
myocyte said:
Quality standards are not reduced over time, but the number of units getting a major inspection off the line can decrease. In order to maintain efficient throughput in manufacturing, not all aspects of the assembly are inspected at 100%.
Click to expand...
While statistical testing is the norm in many companies (and the only thing making sense in many cases), the QC procedure do depend on the type of business you're in. I work for a medical device company, and we do 100% inspection (all units are tested). Most electronic products like mobile phones are 100% tested as well.
 
Upvote 0
#20
+1000!!

Why should it be a lottery to get a decent quality lens from Canon? Those with experience maybe can detect the less than ideal copies and send them back. The casual hobbiest may not and just be stuck thinking that's the best they can do. Also, when someone sends several less than razor sharp new copies back, to say B&H or Adorama, until they find one they like, what happens to those returned copies? Are they sent back to Canon or resold?
 
Upvote 0
Status
Not open for further replies.

Similar threads

Dragon
200-800 test images
Replies
4
Views
4K
Dragon
Dragon
sanj
200-800 vs 100-500
Replies
4
Views
4K
sanj
sanj
sanj
24-105 2.8
Replies
7
Views
3K
danfaz
danfaz
sanj
Lenses with wider opening better?
Replies
21
Views
5K
sanj
sanj
AlanF
TDP has image quality of 600mm f/11 posted
Replies
26
Views
8K
magarity
M
Top Bottom
Home
Forums
Media
Menu