August 22, 2014, 09:43:03 PM

Author Topic: Canon 70d center focus point -bug- problem  (Read 10697 times)

koolman

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Canon 70d center focus point -bug- problem
« on: May 14, 2014, 06:26:49 AM »
Hi,

I was considering upgrading from my t2i to the canon 70d. I use quite a few fast primes at 1.4 like the canon 50mm 1.4, and 35L 1.4.

There is quite a "buzz" on the net - claiming a focus problem with the 70d when using the view finder and center point for maximum accuracy. it seems there is a quirk which does not provide sharp focus.

Can anyone confirm or negate this ? If I cannot focus like my t2i with my fast glass - then the 70d is not for me?
Jerusalem Photographer (canon t2i, 50 1.4, Tamron 17-50 non VC, canon 60mm, canon 35mm L,Samyang 14mm MF,Voigtlander 20mm MF)

Mt Spokane Photography

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Re: Canon 70d center focus point -bug- problem
« Reply #1 on: May 14, 2014, 03:49:11 PM »
Hi,

I was considering upgrading from my t2i to the canon 70d. I use quite a few fast primes at 1.4 like the canon 50mm 1.4, and 35L 1.4.

There is quite a "buzz" on the net - claiming a focus problem with the 70d when using the view finder and center point for maximum accuracy. it seems there is a quirk which does not provide sharp focus.

Can anyone confirm or negate this ? If I cannot focus like my t2i with my fast glass - then the 70d is not for me?

Phase detect autofocus is fast, but is not as accurate as the dual pixel AF or manual AF either.  I have not heard of any issues, do you have links to reliable testers that found a issue?  Usually it is lens related, some lenses do not focus reliably or accurately.  Be sure that the tester is experienced and knows what he is doing.  Beware of posts on forums where testers make incorrect assumptions or use lenses that may not be consistent.
 
I've yet to see any expert reports of a issue that is repeatable using good lenses.
 
Here are some links to people who know what they are doing. 
 
http://www.imaging-resource.com/news/2014/02/27/canon-dual-pixel-cmos-af-autofocus-secrets-of-the-canon-70d-explained
 
DP Review did a lot of testing and has some remarks specifically about AF accuracy.
 
http://www.dpreview.com/reviews/canon-eos-70d/12

koolman

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Re: Canon 70d center focus point -bug- problem
« Reply #2 on: May 15, 2014, 07:38:36 AM »
Hi,

I was considering upgrading from my t2i to the canon 70d. I use quite a few fast primes at 1.4 like the canon 50mm 1.4, and 35L 1.4.

There is quite a "buzz" on the net - claiming a focus problem with the 70d when using the view finder and center point for maximum accuracy. it seems there is a quirk which does not provide sharp focus.

Can anyone confirm or negate this ? If I cannot focus like my t2i with my fast glass - then the 70d is not for me?

Phase detect autofocus is fast, but is not as accurate as the dual pixel AF or manual AF either.  I have not heard of any issues, do you have links to reliable testers that found a issue?  Usually it is lens related, some lenses do not focus reliably or accurately.  Be sure that the tester is experienced and knows what he is doing.  Beware of posts on forums where testers make incorrect assumptions or use lenses that may not be consistent.
 
I've yet to see any expert reports of a issue that is repeatable using good lenses.
 
Here are some links to people who know what they are doing. 
 
http://www.imaging-resource.com/news/2014/02/27/canon-dual-pixel-cmos-af-autofocus-secrets-of-the-canon-70d-explained
 
DP Review did a lot of testing and has some remarks specifically about AF accuracy.
 
http://www.dpreview.com/reviews/canon-eos-70d/12

Here are links about this:

Canon 70D- Serious Focusing Problem!

Canon 70D Focusing Issue
Jerusalem Photographer (canon t2i, 50 1.4, Tamron 17-50 non VC, canon 60mm, canon 35mm L,Samyang 14mm MF,Voigtlander 20mm MF)

neuroanatomist

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Re: Canon 70d center focus point -bug- problem
« Reply #3 on: May 15, 2014, 08:34:46 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.
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Don Haines

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Re: Canon 70d center focus point -bug- problem
« Reply #4 on: May 15, 2014, 08:46:25 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.

Who would have thought that moving a camera a greater distance than the DOF would result in blurry pictures! Next thing you know, people will discover that the 1DX does not focus well with the lens cap on....

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neuroanatomist

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Re: Canon 70d center focus point -bug- problem
« Reply #5 on: May 15, 2014, 09:00:24 AM »
Next thing you know, people will discover that the 1DX does not focus well with the lens cap on....

So that's what I've been doing wrong!!!
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alistairm1

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Re: Canon 70d center focus point -bug- problem
« Reply #6 on: May 15, 2014, 09:02:26 AM »
check this out for a bit more detail.

http://photography-on-the.net/forum/showthread.php?t=1354075


Not all the people reporting issues are as poor at photography as your comments suggest.


neuroanatomist

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Re: Canon 70d center focus point -bug- problem
« Reply #7 on: May 15, 2014, 09:49:36 AM »
check this out for a bit more detail.

http://photography-on-the.net/forum/showthread.php?t=1354075


Not all the people reporting issues are as poor at photography as your comments suggest.

Yep, lots of experts there...

Like the person who states, "I may also try on a T1i to see if FoCal can come up with an MFA number for my 50/1.4 on that."  I wonder how much luck he'll have with that.   ::)

Or all the people saying the 70D has inconsistent AF…but they're using a 50/1.8 which is one of Canon's poorest-focusing lenses. 

Or the person who states, "AFMA should generally correct across the range" of distances, which is far from true.

So, we have a few complaints on the internet, lots of poor testing by 'experts', and the known reality that in any production line there are defective units that make it past QC, so there are undoubtedly a very small number of actually defective units out there. 

That, and claims of a Canon coverup.  Egad, we'd better all switch to Nikon, where that sort of thing never happens.   :-X
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alistairm1

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Re: Canon 70d center focus point -bug- problem
« Reply #8 on: May 15, 2014, 10:08:31 AM »
Just picked a few out of 35 pages-worth.
Better just tell them all to get a 1Dx then all their problems will go away.

Just joined this forum, but it doesn't seem to be all than friendly.

I'll contact the admins to get unregistered.

Sorry to have wasted your valuable time

neuroanatomist

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Re: Canon 70d center focus point -bug- problem
« Reply #9 on: May 15, 2014, 10:21:20 AM »
Just picked a few out of 35 pages-worth.
Better just tell them all to get a 1Dx then all their problems will go away.

Just joined this forum, but it doesn't seem to be all than friendly.

I'll contact the admins to get unregistered.

Sorry to have wasted your valuable time

Sorry you feel that way.  But honestly, I don't see anything in those 35 pages or the two videos the OP linked that are consistent with this being a widespread problem.  Once you eliminate the people who don't know about or haven't tried AFMA, the people who aren't testing properly, the people who are using lenses with known AF inconsistency (Canon 50/1.8, almost every Sigma lens), and the people with unrelated issues (many of which also boil down to user error), and once you subtract the people in that 35-page thread that tested for this specific problem with their 70D and found it worked properly, you really aren't left with much of an issue. 

Particularly in this thread…the OP is wondering if the 70D should not be purchased because of the 'buzz' about this 'problem'.  I see no reason to avoid the 70D over this non-issue.

alistairm1, are you experiencing AF issues with your 70D?  If so, what steps have you performed to identify and troubleshoot the issue?
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alistairm1

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Re: Canon 70d center focus point -bug- problem
« Reply #10 on: May 15, 2014, 10:36:02 AM »
I haven't bought one as I can see other people having problems with theirs.
Just as I wouldn't buy anything else which has issues reported and  which doesn't seem to have any sort of fix available.

I'm sure you are the same.

Or maybe not.

neuroanatomist

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Re: Canon 70d center focus point -bug- problem
« Reply #11 on: May 15, 2014, 10:47:12 AM »
I haven't bought one as I can see other people having problems with theirs.
Just as I wouldn't buy anything else which has issues reported and  which doesn't seem to have any sort of fix available.

I'm surprised you've bought anything at all.  Do you have a dSLR now?  Google search for that camera and 'problems'.  Do a search on anything you've bought - a car, HDTV, computer, whatever, with the word "problems" appended.  I bet you'll get hundreds of thousands if not millions of hits. You'll find forums with people reporting problems of all kinds.  My cars give close to a million 'problems' hits each.  My HDTV gives close to 50 million 'problems' hits.  Over 70 million hits for one of my laptops.  My cars, TV, and laptops have worked flawlessly since the day I bought them.

Reports of problems on the internet are a very poor guide for buying choices. 
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jarrieta

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Re: Canon 70d center focus point -bug- problem
« Reply #12 on: May 15, 2014, 11:02:08 AM »
Have gone through the POTN thread and some people there are even implying that people "without" this problem do not know how to use their cameras. So, I guess the people posting excellent shots on the 70d sample thread don't know how to use their 70ds.

Don Haines

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Re: Canon 70d center focus point -bug- problem
« Reply #13 on: May 15, 2014, 11:19:07 AM »
I haven't bought one as I can see other people having problems with theirs.
Just as I wouldn't buy anything else which has issues reported and  which doesn't seem to have any sort of fix available.

I'm sure you are the same.

Or maybe not.

Alistair, it does not matter which camera model you get or from which company.... you can find "experts" who claim that the camera has problems and that there is a conspiracy. Sometimes these claims are true, like the Nikon oil-on-sensor issue, but in the vast majority of cases it comes from people not knowing what they are doing or having the settings wrong.

A classic example of that is the Tamron 150-600 which came out recently. A number of users were complaining that the AF on the lens would not work, yet they had the camera set into a mode where it would quickly abandon attempts at AF and just "give up", when all they had to do was to set the mode to "continue autofocus".

Auto-focus on fast lenses is very problematic, from any company. The in-focus range of some of those lenses can be less than half of a centimeter. Any forward/backward/up/down/angle movement after you have locked on focus will take you out of focus.. You really need a tripod under those conditions. One of my favourite lenses in the 100L... the DOF on that lens is miniscule... take a picture of a bee wide open and you can't even get the whole head in focus... it's DOF is that narrow! The depth of field calculator gives me a number of <1mm.

With a fast lens used wide open, AFMA is almost essential to good focus, yet few users AFMA their lenses, and of those who do, most do not do it right and may actually be making the problem worse.

« Last Edit: May 15, 2014, 11:23:23 AM by Don Haines »
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AlanF

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Re: Canon 70d center focus point -bug- problem
« Reply #14 on: May 15, 2014, 11:26:38 AM »
My 70D focusses very accurately and consistently with centre spot. It is much, much better than my previous 7D and as good as my 5DIII.
5D III, 70D, Powershot SX50, 300/2.8 II, 1.4xTC III, 2xTC III, 70-200/4 IS, 24-105, 15-85, Sigma 10-20, Tamron 150-600.