Canon EF 24-70L f/2.8 mk I

[jwalsh11]

Hi Everyone,

So I know this has been an issue prevalent in forums all over the place, and I'm pretty behind the times, but I was curious if anyone had found any new work arounds or fixes to this issue. I'm shooting on a t3i with this lens I just picked up from another photographer. They raved about it and as I'm trying to get more experience. I didn't think I would go too wrong with the mk I model. I'm a student and so it seemed like a good way to upgrade and one that I could afford right now. Next upgrade was going to be a new body. However, the lens just won't focus when its around 24mm! I can't quite pinpoint all the lengths it has issues at, so I'll try to get that nailed down. But honestly, any advice would be great. I feel like I'm just out a bunch of money with a crap lens that won't focus. Hopefully that isn't the case.

[ebiggs1]

Easy test, try it on a different camera.  If it doesn't work on two different cameras, it likely needs service.  The good thing about most "L" lenses is, they can be and are worth repairing.

You need to do this simple test in good brroad daylight and not in your dorm or other dark place.  There will be times that it will not achieve focus.  Like too dark or too  close.  Not enough contrast as in a clear blue sky.

I used one of those lenses in business for years.  It is a fine lens.  It should serve you well.

[jwalsh11]

Awesome, I'll try to borrow a camera from a friend and test it out. I'll definitley head outside and find the exact point at which it has issues focusing and try to compare. Also I'll try the different focus systems and try to pinpoint it. Thank you so much for the input. 

[ebiggs1]

IMHO, the two different camera is better than the same camera with different focusing modes.  The camera basically uses the same circuity for both.

[RobertTheFat]

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@ebiggs1 wrote:

IMHO, the two different camera is better than the same camera with different focusing modes.  The camera basically uses the same circuity for both.

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If there's a focusing problem traceable to the camera in the case under discussion, it's not likely to be due to the circuitry. If it were, the camera's whole user community would be screaming.

[ebiggs1]

If one of the componets that is shared by both focus systems fails, it wounld not tell him if the lens was good or not.

What has it to do with the rest of the community?

[TCampbell]

The minimum focus distance for that lens is 1.25' (it doesn't much matter if you're at the 24mm end vs the 70mm end for THIS particular lens.)  That distance is measured from the focus mark on the camera body -- not the front of the lens.  

1.25' is pretty close, but if for some reaso you were trying to focus on a subject closer then that... it would explain why you would be unable to achieve focus.

[TCampbell]

I own this lens and I really like -- so unless your lens is damaged, there's nothing in about the lens itself that should cause this problem.

But... try this...

Switch your camera to "live view" mode and try to take a photo -- see if it focuses when using "live view".

The reason I suggest this is because the camera has two completely different focus systems... when using the viewfinder your camera uses "phase detect" autofocus.  When using "live view" mode the camera uses "contrast detect" autofocus.

If it works in live view but fails when using the viewfinder then it's probably an issue with the camera's phase-detect AF system (not really an issue with the lens -- since you would have just proven that the lens actually can focus.)  

[jwalsh11]

Hey everyone, thanks for the input! I took a string of pictures with the lens wide open at 2.8. 

Here is a folder with a series of images, you can see some just don't seem as clear as others. I honestly just don't know why this is. Is this all the clarity I can get out of this lens? At the 50mm length it seems significantly clearer then the others. 

https://www.dropbox.com/sh/wvqtlckxqmaxagw/AAAF2wZJZnUY4mJ1mO00aDdda?dl=0

Thanks!

[ebiggs1]

It looks like the shorter focal length just appears sharper because of the shorter focal length.  Otherwise they look equal to me but I did not d/l the set.  You can send it to Canon for a clean and check.

It also depends on what you are comparing the lens to.  It isn't as sharp as a 50mm prime lens for instance.  It isn't as sharp as its replcaement 24-70mm version 2 either.