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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 08 May 2009 (Friday) 01:08
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24-70 backfocus

 
baw5t0n
Senior Member
270 posts
Joined Jan 2007
Location: Los Angeles
     
May 08, 2009 01:08 |  #1

I'm sure this topic has been up and around many times for a very long time... but i can't figure out how to optimize the search function to get the answer i want. I have a 5d Classic (i just learned that term 5 minutes ago from one of the ill-searched topics on POTN) and more often than not, my 24-70 back-focuses to the point that it's embarrassing to even print! I took the lens in to Canon in Irvine, but it's still having the same issue... should I take it back with the body? would that help? the puzzling thing is, when it's sharp, it's tack sharp... it does seem sharper when the subject is closer and at the telephoto side of the zoom range.... any thoughts? :confused:


5D/BG-E4 || 28/1.8, 50/1.4, 85/1.8, 100/2.8 Macro, Sigma 17-35/2.8-4.0, 24-70/2.8L, 70-200/2.8L IS
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Retouch ­ UK
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224 posts
Joined Feb 2008
Location: Scotland
     
May 08, 2009 01:35 |  #2

Sorry to hear about your issues.

Id take both camera and body to be calibrated at the same time. Both camera and lens can front/back focus within certain limits and still be within spec.

The problem arises when your lens and camera both back or front focus which compounds the issue.

If the camera front focuses and the lens back focuses then they cancel each other out giving a sharp image.

If you get camera and lend calibrated at the same time Canon should be able to find a middle ground for you. It is a good idea to put in all of your lenses rather than just the one you are having issues with as the calibration of one pairing may put off the pairing of your camera and another one of your lenses.

Chris




  
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rikaro
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153 posts
Likes: 2
Joined Jul 2006
Location: Vancouver
     
May 08, 2009 02:25 |  #3

Is it only your 24-70 that is backfocused? Have you tried it on other bodies?


Matt Kwok
http://www.matt-kwok.com/blog (external link)

  
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andytaro
Member
103 posts
Joined Apr 2009
Location: Seattle, WA
     
May 08, 2009 22:40 |  #4

I've just got a brand new 24-70L from newegg. Initially I thought I got a soft lens but further testing revealed that my new lens has back focus issue. Luckily I have 50D with micro adjustment and adjusted my lens to -17 to get proper focus at 70mm. Howerver at 24mm, it now front focus. I've tested with my 16-35II,and 16-35II does not have any focusing issue. So I am in proceess of returning this bad copy. I am very dissapointed with Canon for this poor Qc. I am paying more than a grand and expect to have a product with better quality.




  
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24-70 backfocus
FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
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