Canon 24-70 f/2.8L mkii Focus Shift

[teedidy]

HI All,

I have just received my (2nd copy) Canon 24-70 f/2.8 mk II. Being a faithful CR follower and reading http://www.canonrumors.com/tech-articles/how-to-test-a-lens/ I begain from the top and followed ever step I could as best as I could. I also have Reikan Focal and ran through every testing option there was available. What I have found suprised me to the point I originally thought I had received the dreaded bad copy.

There is a definite focus shift on the 24-70 mk II. I have found that from f4 to f5.6 it starts to back focus severely  -5 afma vs +3 afma for f2.8 to f4 and +3 afma f5.8 on.

I am surprised there is not more information already out there on this.
I Found this on a competing forum  http://www.fredmiranda.com/forum/topic/1177402 very similar findings

I understand through research you can hold the DOF button down to get around this issue? But would that reduce effectiveness of the f2.8 cross focus points?

After a quick search it appears the Tamron 24-70 has a very similar focus shift issue. 
http://www.lenstip.com/340.5-Lens_review-Tamron_SP_24-70_mm_f_2.8_Di_VC_USD_Chromatic_and_spherical_aberration.html

Does anyone have any advice? At this point I don't know what to do?

Thank you for your time.

[teedidy]

I forgot to mention, This only happens at the long end, 70mm. At 24mm there is no issue at all.

[LetTheRightLensIn]

Did you find it only for close shooting distance or in general?
I found it happens to a considerable degree when shooting near MFD. I haven't looked into it much when shooting at greater distances. I suspect it is OK there.

[teedidy]

Did you find it only for close shooting distance or in general?
I found it happens to a considerable degree when shooting near MFD. I haven't looked into it much when shooting at greater distances. I suspect it is OK there.

Good point. When I am near MFD  at 5 feet away at f4 the Total Depth of Field is only 1.5 inches ( http://www.cambridgeincolour.com/tutorials/dof-calculator.htm )(Assume 20/20 vision on a 10in print )
This is where I see it, because at twice that distance the total depth of field is 6.2 inchs.

[jonathan7007]

I believe my copy of this lens does the same thing, but I am trying to redo my Reikan test (which produced + numbers -- opposite of expected result) and get time and conditions for a better test. Back focus observed in real-world exposures in which I would not expect last-second movement. But perhaps the same as your lens...

[teedidy]

I believe my copy of this lens does the same thing, but I am trying to redo my Reikan test (which produced + numbers -- opposite of expected result) and get time and conditions for a better test. Back focus observed in real-world exposures in which I would not expect last-second movement. But perhaps the same as your lens...

This is my second copy of this lens since I thought the first was a bad copy. I guess if I decide I am going to keep this lens, I need to fully understand what it can and cannot do. I also need to fully understand what I can do to overcome its short comings. I tend to shoot mostly photos around my house with little sticky fingers reaching for the camera. Therefore I tend to shoot a large number of shots inside 3 feet. As long as I keep it at f/2.8 I have no issues, but that will not always be possible.

[Viggo]

Is this normal or is it just the new 24-70?

I've never noticed any shift from other than my 50 L and we all know that has some shift. I also never noticed any shift with any of my 70-200's and I use all lenses up close for 85% of my shots ..

[teedidy]

Is this normal or is it just the new 24-70?

I've never noticed any shift from other than my 50 L and we all know that has some shift. I also never noticed any shift with any of my 70-200's and I use all lenses up close for 85% of my shots ..

In my testing it is only in the longer end 70mm was the worst, 50mm not as bad but still noticeable. Zero focus shifting at 24mm. I Tested out the 24-105. I was unable to find any focus shift at 70mm.

[Viggo]

Is this normal or is it just the new 24-70?

I've never noticed any shift from other than my 50 L and we all know that has some shift. I also never noticed any shift with any of my 70-200's and I use all lenses up close for 85% of my shots ..

In my testing it is only in the longer end 70mm was the worst, 50mm not as bad but still noticeable. Zero focus shifting at 24mm. I Tested out the 24-105. I was unable to find any focus shift at 70mm.

Thanks! I just bought myself a mint used 24-70 mk1 for almost zero
Money so I'll leave the mk 2 for a while..

[Dylan777]

I ran my copy through FoCal again, yesterday. Nothing happen on my copy 24, 35, 50, and 70mm(f2.8 to f8). My copy was from very 1st patch

[Mt Spokane Photography]

HI All,

I have just received my (2nd copy) Canon 24-70 f/2.8 mk II. Being a faithful CR follower and reading http://www.canonrumors.com/tech-articles/how-to-test-a-lens/ I begain from the top and followed ever step I could as best as I could. I also have Reikan Focal and ran through every testing option there was available. What I have found suprised me to the point I originally thought I had received the dreaded bad copy.

There is a definite focus shift on the 24-70 mk II. I have found that from f4 to f5.6 it starts to back focus severely  -5 afma vs +3 afma for f2.8 to f4 and +3 afma f5.8 on.

I am surprised there is not more information already out there on this.
I Found this on a competing forum  http://www.fredmiranda.com/forum/topic/1177402 very similar findings

I understand through research you can hold the DOF button down to get around this issue? But would that reduce effectiveness of the f2.8 cross focus points?

After a quick search it appears the Tamron 24-70 has a very similar focus shift issue. 
http://www.lenstip.com/340.5-Lens_review-Tamron_SP_24-70_mm_f_2.8_Di_VC_USD_Chromatic_and_spherical_aberration.html

Does anyone have any advice? At this point I don't know what to do?

Thank you for your time.

Either exchange it again, or send the lens to Canon for adjustment.  I'd say exchange it if you can.  It might have a issue at 70mm.
 
Due to residual spherical aberration,  a lens focus will appear to shift towards the rear, but the 24-70 should do it only very slightly.  For the most part, its just the depth of field that increases more towards the rear as you stop down.
You can decrease the aperture on this photozone chart and see it.
http://www.photozone.de/canon_eos_ff/773-canon2470f28mk2ff?start=1
 
http://toothwalker.org/optics/spherical.html

[teedidy]

HI All,

I have just received my (2nd copy) Canon 24-70 f/2.8 mk II. Being a faithful CR follower and reading http://www.canonrumors.com/tech-articles/how-to-test-a-lens/ I begain from the top and followed ever step I could as best as I could. I also have Reikan Focal and ran through every testing option there was available. What I have found suprised me to the point I originally thought I had received the dreaded bad copy.

There is a definite focus shift on the 24-70 mk II. I have found that from f4 to f5.6 it starts to back focus severely  -5 afma vs +3 afma for f2.8 to f4 and +3 afma f5.8 on.

I am surprised there is not more information already out there on this.
I Found this on a competing forum  http://www.fredmiranda.com/forum/topic/1177402 very similar findings

I understand through research you can hold the DOF button down to get around this issue? But would that reduce effectiveness of the f2.8 cross focus points?

After a quick search it appears the Tamron 24-70 has a very similar focus shift issue. 
http://www.lenstip.com/340.5-Lens_review-Tamron_SP_24-70_mm_f_2.8_Di_VC_USD_Chromatic_and_spherical_aberration.html

Does anyone have any advice? At this point I don't know what to do?

Thank you for your time.

Either exchange it again, or send the lens to Canon for adjustment.  I'd say exchange it if you can.  It might have a issue at 70mm.
 
Due to residual spherical aberration,  a lens focus will appear to shift towards the rear, but the 24-70 should do it only very slightly.  For the most part, its just the depth of field that increases more towards the rear as you stop down.
You can decrease the aperture on this photozone chart and see it.
http://www.photozone.de/canon_eos_ff/773-canon2470f28mk2ff?start=1
 
http://toothwalker.org/optics/spherical.html

Thank you for your time on this. After spending a few more days with the lens (and since BH is closed for Passover). I have had some more time for testing. I have (am attempting to) uploaded 2 files both taken at f4 about 78 inches away. The live view has achieved perfect focus and has equal ticks before and after the target. The AF photo is back focused and has its first tick in focus behind the target. Before I return for a second time, I want to confirm this is not normal and I should at least see at least one tick in front of the target in focus.

Looking at the photozone review of this lens there is a focus shift, but their copy has 2 ticks in front and 10 behind at f4, (vs mine has no ticks in front).

As a side note, I really do love this lens. The colors are amazing! Everything at f/2.8 is amazing.
As a secondary side note: when I don't use the center focus point and use one of the f/4 or f/5.6 points, the back focus is not as prevalent. I will try to upload some pics of that too.
 

[JP]

Of all the lenses that NEEDED improving is the 24-70 f2.8 L. I can't stand it when I am doing EVERYTHING right... i.e. standing still, bracing my camera tightly, working in good indoor/ outdoor lighting, using a cross point, not shifting the focus... literally taking a picture after being certain there is enough detail to get a good focus lock.. and I am standing directly in front of a person, who somehow manages to become like......3 ft back focused! Why...  That should not happen with Professional equipment!!!!!!!!!!  Why would Canon not fix that HUGE problem in the MkII version of this lens...  a new lens that costs SIGNIFICANTLY MORE money than the cruddy lens that I have put up with for the last 10 years!! This problem has peed-off so many photographers that Google.com is filled with many pages of people all over the world complaining about the focus problems!  Oh wait... I know what the flaw is...  There is none.... This lens was designed this way intentionally, because they know that if we are angry about the cruddy performance of such a lens, we would have to buy a new one, thinking that Canon would have corrected all the problems that the last version was known for!  Oh no!  That stuff will be fixed in the MkIII version... costing a whole lot more than the MkII...  Follow the money!  Canon is known for releasing products with MAJOR flaws.....and for denying problems ever existed.......even after stacks of evidence show otherwise!  Jerks!   

[Viggo]

Of all the lenses that NEEDED improving is the 24-70 f2.8 L. I can't stand it when I am doing EVERYTHING right... i.e. standing still, bracing my camera tightly, working in good indoor/ outdoor lighting, using a cross point, not shifting the focus... literally taking a picture after being certain there is enough detail to get a good focus lock.. and I am standing directly in front of a person, who somehow manages to become like......3 ft back focused! Why...  That should not happen with Professional equipment!!!!!!!!!!  Why would Canon not fix that HUGE problem in the MkII version of this lens...  a new lens that costs SIGNIFICANTLY MORE money than the cruddy lens that I have put up with for the last 10 years!! This problem has peed-off so many photographers that Google.com is filled with many pages of people all over the world complaining about the focus problems!  Oh wait... I know what the flaw is...  There is none.... This lens was designed this way intentionally, because they know that if we are angry about the cruddy performance of such a lens, we would have to buy a new one, thinking that Canon would have corrected all the problems that the last version was known for!  Oh no!  That stuff will be fixed in the MkIII version... costing a whole lot more than the MkII...  Follow the money!  Canon is known for releasing products with MAJOR flaws.....and for denying problems ever existed.......even after stacks of evidence show otherwise!  Jerks!

Have you afma'd to both tele and wide end?

My 24-70 mk2 is just astonishing when it comes to locking and tracking with any of the 61 points. I can hardly get it to miss if I try. And I shoot running small children indoors.

[JP]

Yes... I believe you when you say that you can get remarkable shots with it tracking subjects in AI-servo...  I have found the same when shooting HS sports inside a poorly lighted gym...  but when it comes to the most obvious shot that one would expect an f2.8 L lens to get focused, when the AF point is confirmed in One Shot, on top of someone's face who is standing between 3-20 feet in front of you...  why it does not accurately focus is beyond my understanding..  I have resorted to using manual focus for those types of shots, for I get far better, &  consistent results.