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Full Version: next PZ lens test report: Canon EF 24-70mm f/4 USM L IS (on APS-C)
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Still a great performer ... with a bug:

http://www.opticallimits.com/canon-eos/8...2470_4apsc

Guest

So is a bug better or worse than a design flaw ?

your choice  Rolleyes

HarryLally

I really can't see how Canon can release this lens onto the market. It's got such a serious design flaw that it's not fit for purpose. It should be the ideal lens for me to go with the 70-200 f4L Is but as it is I will stick with the slightly heavier but less sharp 24-105 f4L.

Quote:I really can't see how Canon can release this lens onto the market. It's got such a serious design flaw that it's not fit for purpose. It should be the ideal lens for me to go with the 70-200 f4L Is but as it is I will stick with the slightly heavier but less sharp 24-105 f4L.
There are many who use this lens without reported problem... From what I have seen, they use a 6D. It might be that with AF it is camera body dependent, this focus shift. I have no way of checking that, but it might be worth checking it out.

HarryLally

Thanks BC.

I have the 5DII, same as Klaus. I'll check the lens out with 6D users over at DPR. Also, I think DPR will be testing the lens soon on a 6D, which seems to be their current Canon FF body used  for testing. No doubt they'll have read Klaus' review and will look into the 'problem'. They have also commented in the recent 24-70 f2.8L II review that the AF was fast and very accurate with the 6D and a bit hit-and-miss with the 650D. So maybe the AF accuracy is body dependent. I'd be very surprised if RSAs were body dependent though.

Just to mention once more - the RSA test was done with deactivated AF.

The AF is fine at max. aperture.

HarryLally

Are you saying that if one uses AF, then the focus shift will not be a problem?  i.e. that the camera will correct it in some way?

Quote:Are you saying that if one uses AF, then the focus shift will not be a problem?  i.e. that the camera will correct it in some way?
 

No, I said "at max. aperture". :-)

Theoretically it could apply a correction factor (Pentax does so I remember) but this does not seem to be the case with the test cameras. Possibly newer EOS cameras can do it. 

 

And to be somewhat more precise - you will probably never experience the effect when shooting at f/11 because the DOF catches up with the RSAs. 

The really critical setting is f/4 or f/5.6 at close focus distances.

JohnMc

Crystal ball stuff-

Do you think RSA issue likely in all copies, at least to some build date?

Is Canon likely to correct issue, or is it destine to be forever 'feature'?

 

(EOS newbie with no EOS glass between 22 and 70mm.)

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