Canon 24-70 2.8 II

[fremen9]

Last year I sold some lenses so I could buy the 24-70 2.8 II.  I had really liked the Tamron 17-50 2.8 on my Rebel, but now that I had a Canon 6D I needed a full frame lens. The 24-70 was great...however, I found that I had to shoot at F4 to get really sharp pictures...and I was never too happy with it at 2.8.

I remember people told me it was probably user error..and I know that occasionally I'd get tack sharp photos at 2.8 but just not always.   

anyway,  recently I bought the Sigma 50mm 1.4 ART.  I found that I needed to use microadjust about -4 to get most of my shots in in focus.  Its amazing.  I'm often shooting at F2 or 2.8 and getting beautiful and IN-focus pictures. 

This makes me realize now, that its not user error...if i'm able to get tack sharp photos with this sigma lens at F2.0 and 2.8...then I should also be able to get in-focus shots at 2.8 on the Canon.  I'm not expecting the Canon to be as sharp...I'm talking about the focus just being off.

So I'm finally taking the lens into Canon service center tomorrow to see what they can do.  I should have done that from the beginning...but without another lens to test it against or try out...it was easy to believe it was just user error. 

Just sharing this story in case it helps anyone.

[f64]

Once you get your lens back there is another way to check the focus on your body. I own one manual focus lens that I use. Although I get a confirming VF screen indication when I focus manually there is still some room for improvement or, in my case, altering the focus point.

Try this:

1) In Live View - auto focus as normal

2) Hit the magnification button, usually to 10X or beyond

3) Check the focus against a manual adjustment

If you can still sharpen the focus point beyond what the AF has selected there are two options: recalibrate the lens to the body, or alter the AF selection.

Once you get your lens back tell us what you find. That's a great lens and it should serve you well. Once it's working you'll probably find that becomes your go-to lens. It did for me.

[TCampbell]

You might want to read:   http://www.lensrentals.com/blog/2008/12/this-lens-is-soft-and-other-myths

If you're going to send the "lens" in for testing (becuase the 24-70mm f/2.8L IS USM II is an extremely good lens) then you probably need to send BOTH the camera AND lens so they can be evaluated as a pair. 

Also, whenever you suspect a lens is not focusing accurately, you really should use a proper focus test chart and the camera should be mounted on a tripod.  

[fremen9]

TCampbell, I suppose it might be nice to have them calibrate the lens so it matches my camera body...but my camera body is currently working great with two other lenses...if they mess with it...I think (hope) the problem is that my canon 24-70 lacks precision and so if that's fixed, then I can use micro adjust so it matches well on my camera body.

I read this article.

http://www.the-digital-picture.com/Photography-Tips/af-microadjustment-tips.aspx

If you look at that article it talks about how micro adjust only fixes accuracy, not precision.  So if my lens isn't precise..then adjusting the accuracy bias won't help.

anyway its with canon now. so let's see what happens!!   They quoted me $215 (after discount) to start....

[amfoto1]

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@fremen9 wrote:

Last year I sold some lenses so I could buy the 24-70 2.8 II.  I had really liked the Tamron 17-50 2.8 on my Rebel, but now that I had a Canon 6D I needed a full frame lens. The 24-70 was great...however, I found that I had to shoot at F4 to get really sharp pictures...and I was never too happy with it at 2.8.

I remember people told me it was probably user error..and I know that occasionally I'd get tack sharp photos at 2.8 but just not always.   

anyway,  recently I bought the Sigma 50mm 1.4 ART.  I found that I needed to use microadjust about -4 to get most of my shots in in focus.  Its amazing.  I'm often shooting at F2 or 2.8 and getting beautiful and IN-focus pictures. 

This makes me realize now, that its not user error...if i'm able to get tack sharp photos with this sigma lens at F2.0 and 2.8...then I should also be able to get in-focus shots at 2.8 on the Canon.  I'm not expecting the Canon to be as sharp...I'm talking about the focus just being off.

So I'm finally taking the lens into Canon service center tomorrow to see what they can do.  I should have done that from the beginning...but without another lens to test it against or try out...it was easy to believe it was just user error. 

Just sharing this story in case it helps anyone.

---

Did you try Micro Adjusting the 24-70 on your 6D?

If not, why not? If it worked for the Sigma lens, it should work for the 24-70 or most any other lens, too.

***********

Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & EXPOSUREMANAGER 

[fremen9]

The reason I didn't bother trying micro-adjust on the 24-70 is that it wasn't backfocussing or front focussing consistently. 

See the micro adjust is only useful if the scatter of focus is shifted in one direction or the other.  But in this case. it was simply focussing so terribly on 20 out of 80 shots, that there was no way micro adjust would help with that. . The other 60 shots were in focus and looked fine...it was the 20 that were just awful...not slightly front or back but like i had focussed on infinity... if I messed arond with micro adjust, i would ruin the 60 good shots for the sake of the 20 bad ones?   

I did quite a bit of reading about micro adjust when I first got my Sigma and noticed it was always backfocusing.

During testing, the camera was mounted on a tripod. 

I also used the same camera/tripod and target with my Sigma 50mm 1.4 ART shooting at F2.0 and was able to get over 90% in focus, after using micro adjust.  

I definitely would prefer just using micro adjust on the 24-70..but for that to work, it needs to be at least "close" and has to be almost always backfocussing or front focussing...not random...

Its funny though...another photog I know posted on his fb wall about how he is used to 20% out of focus shots on his canon 70-200 2.8 L.   So he shoots a lot of extra pictures now.    

[RobertTheFat]

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@fremen9 wrote:

The reason I didn't bother trying micro-adjust on the 24-70 is that it wasn't backfocussing or front focussing consistently. 

See the micro adjust is only useful if the scatter of focus is shifted in one direction or the other.  But in this case. it was simply focussing so terribly on 20 out of 80 shots, that there was no way micro adjust would help with that. . The other 60 shots were in focus and looked fine...it was the 20 that were just awful...not slightly front or back but like i had focussed on infinity... if I messed arond with micro adjust, i would ruin the 60 good shots for the sake of the 20 bad ones?   

I did quite a bit of reading about micro adjust when I first got my Sigma and noticed it was always backfocusing.

During testing, the camera was mounted on a tripod. 

I also used the same camera/tripod and target with my Sigma 50mm 1.4 ART shooting at F2.0 and was able to get over 90% in focus, after using micro adjust.  

I definitely would prefer just using micro adjust on the 24-70..but for that to work, it needs to be at least "close" and has to be almost always backfocussing or front focussing...not random...

Its funny though...another photog I know posted on his fb wall about how he is used to 20% out of focus shots on his canon 70-200 2.8 L.   So he shoots a lot of extra pictures now.    

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When my main camera was a 50D (whose AF system is, I believe, pretty much that of the 6D), I had the same problem as you and your friend: a large percentage of my shots were OOF. By the time I had phased out the 50D in favor of a pair of 7D's, my OOF problem went down dramatically. When I added a 5D3 and it became my main camera, the problem again diminished greatly. While I still have a couple of lenses that need AFMA, focusing is simply not a significant problem anymore.

The 6D is a compromise design intended to meet a given price point, and I think most would probably agree that its AF system is its greatest weakness. With AF, as with many other things, you get what you pay for.

[fremen9]

I'm actually a fan of the Canon 6D and don't use it as my main camera because of its price point but because I like it better.

In the past year I went through phases where I tried to "upgrade" or replace it with something better.

First I got a Canon 5DIII.   After using it on shoots for a few months, I went back to using the 6D.  Why?  Because the 5D3 was heavier/bulkier, and its center point was always hunting for focus in low light.  I just got used to the 6D and I wasn't getting better shots with the 5D3 anyway. . 

Then, I even tried out Nikon, and got a Nikon D810 with the Nikkor 85mm lens that is rated very high.  I also tried the Nikon 24-70 2.8 lens with it.   after 2 months...I did shoots where I used both my 6D with the Canon 35MM 1.4L and the Nikon D810 with the 85mm and guess what...after those 2 months I returned the Nikon gear and decided to stick with Canon and my 6D.

Its only this particular lens that has had issues...but the 6D is an amazing camera...especially considering the price. I almost feel like Canon goofed making it too good for that price.   I believe its just a bad copy of the 24-70 that is giving me issues.  

By the way I used to shoot with a 5D Mark II, and that thing had much worse focus than my 6D...yet so many people shot weddings with it... 

I don't do action photography, I shoot portraits mainly.  

here's a few I took recently with my trusty 6D using the canon 24-70 but at F4 (as long as i re-focus it gets great shots at F4/F5)

http://fremen.smugmug.com/photos/i-KMrG2Tg/0/X3/i-KMrG2Tg-X3.jpg

http://fremen.smugmug.com/photos/i-gzMXVBr/0/X3/i-gzMXVBr-X3.jpg

[amfoto1]

Well, it sounds as if you have tried everything and will probably need to send the lens in to be checked out.

We all have our own expectations for focus accuracy... what's "usable" and what's not. I wouldn't be happy with 80%. I get better than 97 or 98% with my 7Ds... shots I can use in terms of focus (not necessarily usable for other reasons such as composition, exposure, etc.).

My percentages are not as good with my 5DII, but that's a much less capable AF system and I take a lot fewer shots with it, so part of it may be practice.. It was a shame that the Mark II's AF system wasn't improved at all from the original 5D's. Basically the same AF system was in the 5D line for about 7 or 8 years. Otherwise, the Mark II was a nice upgrade to the original. For me, they've been fine for portraiture, macro and landscape (actually, I can see why they've been so popular for weddings). Just not very good for anything moving.

I don't have 6D.  But I've heard and read it's center point is the best of it's 11-point system, by a wide margin. It's the camera's only dual axis point, and is unusually low-light capable (5DIII has five such points at the center and 41 throughout the array, out of it's 61 total.)

No, the 50D's AF system is superior to the 6D's in at least one respect. All 9 of the 50D's AF points are the better dual-axis. cross type. The 50D's peripheral points are more usable than the 6D's peripheral points, all of which are single-axis type. The 6D's center point is definitely superior to the 50D's center point, though. It's able to achieve focus in lower light than any other Canon model I'm aware of. Before getting my 7Ds I shot a lot with several 50Ds, too, and got about 94 or 95% acceptibly in focus with them. But, again, what I find usably in-focus may be different from what someone else might find acceptible and usable.

Don't have the 24-70 II, either. I am still using the first version of that lens.  

***********

Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & EXPOSUREMANAGER 

[ebiggs1]

I have not responed to this because Alan Myers and Tim Campbell did a wonderful job of it.  But...............

"If you're going to send the "lens" in for testing (becuase the 24-70mm f/2.8L IS USM II is an extremely good lens) then you probably need to send BOTH the camera AND lens so they can be evaluated as a pair. 

Also, whenever you suspect a lens is not focusing accurately, you really should use a proper focus test chart and the camera should be mounted on a tripod."

This CAN NOT be understated.  Not necessarily the 6D but the EF 24-70 f2.8mm L is such a hig quality and tested lens.

This is very important, "...you ... need to send BOTH the camera AND lens (in) so they can be evaluated as a pair."