August 21, 2014, 01:01:23 AM

Author Topic: Canon 70d center focus point -bug- problem  (Read 10614 times)

PicaPica

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Re: Canon 70d center focus point -bug- problem
« Reply #30 on: May 16, 2014, 05:43:07 AM »
Quote from: Mt Spokane Photography

There are plenty of web sites that do competent testing of products, and a few that don't. 
 
I'd suggest that you take advantage of advice from the many good photographers on this site, and go to some of the premiere test sites and read actual test reports rather than taking posters in forums at face value.  Many forums have some really good photographers, but the test sites tend to be a cut above because they have expensive software and the knowhow to avoid the pitfalls that do it your self experts step into. 

When was the last time one of the websites you mention have found a bug in one of the products they have tested? Found! Not just reported.

The light leak bug in the 5D MK3.
Not a bug some say.. yet canon has fixed it.

The "white rubber" issue.

Tons of other examples where the "Bugfinder" are ordinary people in photography forums.

A testchart and other testgear will not help you find issues outside their line of use.
Review sites are usually in a hurry to get their reviews out. Longtime tests.. who does them, beside Lensrentals?

Don´t be naive. :) No review websites can test everything. 
It is the same as with car magazines.
If you would believe them no car ever would need a recall.
« Last Edit: May 16, 2014, 05:59:30 AM by PicaPica »

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Re: Canon 70d center focus point -bug- problem
« Reply #30 on: May 16, 2014, 05:43:07 AM »

PicaPica

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Re: Canon 70d center focus point -bug- problem
« Reply #31 on: May 16, 2014, 05:57:36 AM »
Here are links about this:

Well, the first video is a useless joke.  Evidence?  I see none.  Zero information about the lens used, the camera settings, or the set up.  The most obvious answer to that "problem" is that the lens needs AFMA – sharper with live view than with phase AF is the easiest test to determine that.  I chuckled at the claim that "a good knowledge of photography" is necessary to detect the problem. That's what we call irony.  ::)

The second video says exactly what I just said – the focus was off with the 50/1.4 at f/1.4, and AFMA corrected the problem. Duh. He then goes on to suggest there is, in fact, a problem with some cameras – but he has no evidence for that, except "some people on the Internet say"…

Were these two videos the best 'evidence' you could come up with?  I think the only problems you're seeing are wetware errors – the person holding the camera is the issue.

I guess you have not read the discussions about it?
No amount of AFMA will fix the problem.

As it was stated by Lightmaster.. that does not explain why other Canon Bodys work fine with the same lens type.

His argument that advanced Photographers do not suddenly become newbies when they use a 70D makes sense.




neuroanatomist

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Re: Canon 70d center focus point -bug- problem
« Reply #32 on: May 16, 2014, 08:46:27 AM »
60D was able to find the point of sharpest focus every time.
the 70D not, but with contrast AF the 70D was fine.

I have several lenses which needed 10 units or more different AFMA settings on different bodies – over a full depth of focus off.  So it's easily possible that a 60D could focus correctly and a 70D could be way off with the same lens.

In the case where the center AF point consistently misses focus, but an immediately adjacent AF point consistently achieves correct focus (assuming equivalent directional contrast for both points), that pretty clearly indicates a hardware or firmware defect.  So far, I've seen one – just one – example of that.

There's also confirmation bias...one person with a defective camera posts information about it (perhaps in German on a German forum?), and suddenly many people 'find' the same problem (if they read German?), except their cameras are fine, it's their testing that's defective.


Tons of other examples where the "Bugfinder" are ordinary people in photography forums.

Canon doesn't care about 'bug reports' on Internet forums.  Anyone who thinks their camera is defective should send it to Canon.  It seems that several people have done so, and been told that their camera is within spec.  A Canon 'coverup'?  No, you can put away the conspiracy theories.  The simple answer is their cameras weren't defective. 

When there's an issue, Canon fixes it.  If a hardware issue is widespread, Canon issues a Product Advisory; firmware issues are fixed with a firmware update. 
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Don Haines

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Re: Canon 70d center focus point -bug- problem
« Reply #33 on: May 16, 2014, 09:14:14 AM »
It's the claim of 35-50 percent of people in Germany have this problem that gets me....

The logic is flawed. If the problem is so widespread in Germany, it must be the same elsewhere, so why is it not showing up elsewhere in those numbers?



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dadgummit

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Re: Canon 70d center focus point -bug- problem
« Reply #34 on: May 16, 2014, 11:18:08 AM »
I don't know if there is a bug or not but I just purchased a new 70D from B&H last week and the center focus point works perfectly with the 85mm f1.2 and other faster than f2.8 lenses.

Personally I am willing to bet that there are a few defective cameras out there with some kind of issue and when other people start pixel peeping their fast lenses at long distances the are surprized that the camera has issues getting a sharp f1.4 shot at 20 feet out.  So they think they have the issue too. 

Whenever I shoot a wedding with low light I have the cameras in High speed continuous all the time.  Out of 4 shots of the bride eating her cake maybe 2 are in perfect focus.  The ironic thing is that she will often choose one of the less perfect shiots for her 8x10 and guess what it, comes out great!  Pixel Peeping has made the lives of Canon's engineers in the af department very difficult. 

unadog

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Re: Canon 70d center focus point -bug- problem
« Reply #35 on: May 16, 2014, 11:30:37 AM »
What we need to see to know if there really is a problem is an autofocus test similar to those done by Roger Cicala.

Every auto focus system will deliver a range of values. Look at how he measured the accuracy of focus on different bodies and different lenses.

He did 10 repeated focus attempts with phase detection and manual focus. Gave us the standard deviation of the focus error.

Compared that between older Canon bodies and newer Canon bodies. And also found out that newer lenses focused more accurately.

So you need to repeat the focus test 10 times, because it will vary. Measure those errors. Use one of the newer Canon lenses. And compare that to cameras of the same class - 60D, 50D, T4i.

SHOW US THE STATISTICALICAL ANALYSIS. ACCOUNT FOR KNOWN VARIATION IN PERFORMANCE.

Show that you understand the system well enough to demonstrate an anomoly.

Most of this is just people finally learning how auto focus works.

Please, read these articles. Then we can talk:

Roger Cicala's posts on auto focus:

Autofocus Reality Part 1

http://www.lensrentals.com/blog/2012/07/autofocus-reality-part-1-center-point-single-shot-accuracy

http://www.lensrentals.com/blog/2012/07/autofocus-reality-part-ii-1-vs-2-and-old-vs-new

http://www.lensrentals.com/blog/2012/08/autofocus-reality-part-3b-canon-ca


Roger Cicala: "Why You Can't Optically Test Your Lens With Autofocus"

 http://www.lensrentals.com/blog/2014/02/why-you-cant-optically-test-your-lens-with-autofocus
« Last Edit: May 16, 2014, 12:03:31 PM by unadog »

unadog

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Re: Canon 70d center focus point -bug- problem
« Reply #36 on: May 16, 2014, 11:36:47 AM »
Roger Cicala: "Why You Can't Optically Test Your Lens With Autofocus"

http://www.lensrentals.com/blog/2014/02/why-you-cant-optically-test-your-lens-with-autofocus

To summarize my point, if I am checking a lens like our techs do all day, manual focus is simply much more accurate than phase-detection autofocus.
 



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Re: Canon 70d center focus point -bug- problem
« Reply #36 on: May 16, 2014, 11:36:47 AM »

unadog

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Re: Canon 70d center focus point -bug- problem
« Reply #37 on: May 16, 2014, 11:40:46 AM »
More text from that article:

"Let me again differentiate ‘testing quality focus’ from ‘picture taking focus’.

If I was taking a 3-Dimensional picture, all of the images above the 850 line would be virtually indistinguishable. The two phase-detection shots that are lower would probably be acceptable; if you were comparing identical shots you might notice the two had slightly missed focus, but not horribly.

But when we’re assessing a 2-dimensional test chart, that would be enough to make the lens look unacceptable.

Phase detection accuracy is different with different cameras and even with different lenses on the same camera. The pair used in this example are quite accurate; not the very best, but better than average. The very best (in these conditions) we’ve tested, the Canon 5DIII or 1Dx with certain lenses, are nearly as accurate as contrast detection AF.


Good microfocus adjustment lets the phase detection system focus at the proper location, but it can’t make the pattern of variation much smaller. (If MF adjustment is really off, the pattern can be bigger than this, but this is about as good as it gets.)

One other point that will become more apparent with the next two posts: some of the most sensitive indicators of a decentered lens are seen when it’s just barely out of focus. So the testing I’m going to describe will require evaluating the lens both in focus, and just barely out of focus in both directions. You can’t do that kind of evaluation with phase-detection AF.

So What’s Next?

This first post was to demonstrate that hand-held, autofocus optical testing isn’t very useful. If you want to test a lens using autofocus go take pictures and see if you like the lens, which is really what I recommend everyone do, anyway.


unadog

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Re: Canon 70d center focus point -bug- problem
« Reply #38 on: May 16, 2014, 12:11:54 PM »
OLD Lens  Versus NEW Lens



http://www.lensrentals.com/blog/2012/07/autofocus-reality-part-ii-1-vs-2-and-old-vs-new

The OLD Canon 24mm f/2.8 lens was released in 1988 making it one of the oldest designed Canon lenses available.

 while the NEW Canon 24mm f/2.8 IS USM was just released last year.


GRAPHS IN ORDER:

1.) The OLD 24 mm on an OLD 5D Mk2

2.) The OLD 24 2.8 on a NEW 5D M3

3.) The  NEW 24 2.8 IS on a NEW 5D M3


Look at that last graph! Newer lenses are amazingly good on a newer body.
« Last Edit: May 16, 2014, 12:15:42 PM by unadog »

David_in_Seattle

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Re: Canon 70d center focus point -bug- problem
« Reply #39 on: May 16, 2014, 01:04:18 PM »
I rented a 70D right when it was released to compare it to my aging 60D for both photos and videos (primarily for video).  I never encountered a problem using the center AF point with a fast prime (50mm f1.2, 85mm f1.2, Sigma 18-35 f1.8 ) under normal lighting conditions.  Note: all cameras will have problems focusing on low contrast subjects or in poor lighting conditions; for that I recommend attaching a Canon speedlite.

When using the live view the AF phase detection system is very useful, though it also has problems focusing on low contrast subjects.  I've used it to record a break dancing competition under terrible lighting conditions while using the Canon 17-55 f2.8 IS.  Overall, focusing was hardly a problem whereas most of my concern was recording at ISO 3200.

Ultimately I recently decided to buy a 70D to replace my 60D.  I prefer using the 70D for run and gun video recording compared to my 5Dmk3 and 1Dx because it's lighter and has a useful live view AF system.
« Last Edit: May 16, 2014, 01:05:59 PM by David_in_Seattle »
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Mt Spokane Photography

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Re: Canon 70d center focus point -bug- problem
« Reply #40 on: May 16, 2014, 02:05:03 PM »
Quote from: Mt Spokane Photography

There are plenty of web sites that do competent testing of products, and a few that don't. 
 
I'd suggest that you take advantage of advice from the many good photographers on this site, and go to some of the premiere test sites and read actual test reports rather than taking posters in forums at face value.  Many forums have some really good photographers, but the test sites tend to be a cut above because they have expensive software and the knowhow to avoid the pitfalls that do it your self experts step into. 

When was the last time one of the websites you mention have found a bug in one of the products they have tested? Found! Not just reported.

The light leak bug in the 5D MK3.
Not a bug some say.. yet canon has fixed it.

The "white rubber" issue.

Tons of other examples where the "Bugfinder" are ordinary people in photography forums.

A testchart and other testgear will not help you find issues outside their line of use.
Review sites are usually in a hurry to get their reviews out. Longtime tests.. who does them, beside Lensrentals?

Don´t be naive. :) No review websites can test everything. 
It is the same as with car magazines.
If you would believe them no car ever would need a recall.

All of the things you mention were investigated or reported on the major sites.  I haven't heard of the light leak causing a actual issue, since you must have a lens cap on to detect it.  Likewise, the white rubber issue has been around off and on for at least 30 years, and affected Minolta and Nikon most.  They did not acknowledge or fix it, while
canon did. 
 
Its true, tons of people find Bugs that are a issue, and 100 times more that cannot be confirmed.  The issue comes when knowledgeable testers all over the world have not been able to find the issue, and even more amazing if 35% of the owners in Germany are so good at testing that they have found it.
 
I'm a skeptic, but there are certain people who I have followed over the past 20 years that have a good record for careful testing.  Most test sites do not just test in a lab, but also test in the field, people throw up the "Real World" excuse because careful testing does not support their theory, rather than using it in conjunction with lab tests.  I have had and operated a lab that did reports for Nasa, and we do look at standard tests, and certainly cannot test for everything, so having lots of users reporting issues they find is a good thing, but that does not mean that even 0.001 percent are actual problems.  Most of them turn out to be operator error, or defective equipment.

3kramd5

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Re: Canon 70d center focus point -bug- problem
« Reply #41 on: May 16, 2014, 03:51:56 PM »
Roger Cicala: "Why You Can't Optically Test Your Lens With Autofocus"


While Roger is correct, that has zero bearing on this topic.
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ishdakuteb

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Re: Canon 70d center focus point -bug- problem
« Reply #42 on: May 16, 2014, 04:37:49 PM »
still remember those days before i was making a final decision to buy my canon 7d, went on internet to do bunch of research.  what i got were number of complains on canon 7d focus problems.  there was a little hesitate about making a final call, i decided to go to best buy and tried it myself before pulling a trigger.  i ended up buying canon 7d with carrying a thought...

1. if there was focus problem found, then i would return it,
2. buying canon 7d will save the quite a bit of money for coming canon 5d mark iii

now, i am still using it without any problems so far.  however, there was a time that i had focus hunt problem with canon 7d, that was the time when i was trying to focus on a humming bird:

1. In a frame with bright sky and bird was relatively kinda small in the frame,
2. With single focus point,
3. Full range of zoom, on canon 70-200mm is mark ii, was set

why was that?  setup and try to see where is the problem...  however, there is a easy test on this...  have one person sitting by a window that lit up with a bright light, try to focus on that person to see how fast and  how accurate you can nail the focus...

disclaimer:  i am not a pro. nor a person who has used slr for 20 years.  i am just a hobbyist sitting at home learning digital photography after working hours (yes, sometimes during work hours too lol...).  my main target now is post processing, but still not forgetting about practicing everyday... sometimes with camera, sometimes with thoughts

changing a brand is not a choice to me since i do believe that if someone can deliver a good image with my current system while i am not able to, that is my fault... not learning enough... and i have invested quite a big on current setup...

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Re: Canon 70d center focus point -bug- problem
« Reply #42 on: May 16, 2014, 04:37:49 PM »

steve25

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Re: Canon 70d center focus point -bug- problem
« Reply #43 on: May 16, 2014, 06:00:58 PM »
Here are links about this:


Well, the first video is a useless joke.  Evidence?  I see none.  Zero information about the lens used, the camera settings, or the set up.  The most obvious answer to that "problem" is that the lens needs AFMA – sharper with live view than with phase AF is the easiest test to determine that.  I chuckled at the claim that "a good knowledge of photography" is necessary to detect the problem. That's what we call irony.  ::)

The second video says exactly what I just said – the focus was off with the 50/1.4 at f/1.4, and AFMA corrected the problem. Duh. He then goes on to suggest there is, in fact, a problem with some cameras – but he has no evidence for that, except "some people on the Internet say"…

Were these two videos the best 'evidence' you could come up with?  I think the only problems you're seeing are wetware errors – the person holding the camera is the issue.
 

Have you seen these videos? are they joke as well? Some newbies experimenting with the latest game changer from Canon?
Small | Large
If the language is a problem, this video may help uderstanding the issue better
Small | Large

neuroanatomist

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Re: Canon 70d center focus point -bug- problem
« Reply #44 on: May 16, 2014, 10:47:06 PM »
Have you seen these videos? are they joke as well? Some newbies experimenting with the latest game changer from Canon?

If the language is a problem, this video may help uderstanding the issue better

In the first video, it's often hard to tell if a resulting shot shown on the 70D's LCD is sharp or not - the video was apparently shot handheld and the cameraperson is moving back and forth a lot, so that LCD is often blurry due to poor focus of the video.  A lot of newbies shoot poor video like that, then they discover something called a tripod.   ::)  I do get the gist of the problem, though.  As for correcting it with AFMA, I would not expect selecting AFMA values apparently at random would be an appropriate way to see if AFMA is beneficial.  The fact that he's a well-known reviewer doesn't mean he necessarily knows what he's doing.  I've pointed out issues with his testing previously

As for the second video, perhaps you missed the update: "I sent my 70D into the Canon Service center and now have it back. They responded that image sensor was incorrect and electronic adjustments were made.  I have just started preliminary testing and can say that the difference between live view and viewfinder sharpness is still noticeable and sometime significant but seems to be almost completely corrected with AF Micro Adjustments – something that was not possible before."

That sounds like exactly what I stated previously…if you think your camera is defective, send it to Canon, and if they find it to be defective, they'll fix it…as they did in the case above.  The difference in sharpness between Live View and SIR-PDAF is normally correctable with AFMA.

So far, I see a couple of cameras that appear defective, one of which was repaired by Canon.  Not counting a few 'me, too' Internet forum posts backed up by poor testing or none at all, it's not exactly consistent with a 'widespread problem'.  If it really is a widespread issue, Canon will figure it out by cameras sent in for repair, not by posts on the Internet.
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Re: Canon 70d center focus point -bug- problem
« Reply #44 on: May 16, 2014, 10:47:06 PM »