[toni-a]

My EFS-17-55 f2.8 is consistently front focusing on 750D while it focuses acurately on 30D.

Other lenses focus extremely fine on my 750D even my 50mm f1.4 is perfectly spot on.

What do you think should be done ?

 

 

[Brightcolours]

The lens should be calibrated on the 750D. It is not uncommon for a lens to do ok one body with a different AF system, and less ok on another.

I am guessing that the lens will not front focus when you set the camera to AI-Servo?

[toni-a]

in dpreview review the camera seems to suffer such a problem, maybe a firmware update is needed ?

 

http://www.dpreview.com/reviews/canon-eo...-t6s-t6i/4

[Brightcolours]

There is no such problem mentioned on that page?

Can you answer the question from my above post?

[toni-a]

The lens front focuses in whatever mode, but it's fine in live view.

In the review the camera had a focus issue with a specific lens, same as I am having

[Brightcolours]

So you did verify that the lens front focusses when specifically using AI-Servo too? AI-Servo does not have the same issues in PD AF concerning the lack of not checking if things ended up in focus.

 

Again, you have to send in the lens preferably with the body, to have the lens calibrated. The steps the lens makes and the steps the camera thinks it makes are not "in sync".

 

Live view is totally not connected to PD AF, so how the lens performs there is of no interest, really.

 

And concerning "firmware update", it is something that is not abnormal for PD AF, to have one lens or more not be in line with the AF system of the camera. It happens. And then the answer is always: you have to have the lens calibrated for that body. Some DSLRs are better than others in avoiding these issues, especially the current 5D series and 1D series have very few issues in this area And the 70D and up also seem to perform really rather accurately).

 

To illustrate the unpredictability of this concerning different bodies:

 

My 1st DSLR was the Canon EOS 350D, a little bit notorious for AF unpredictability. My Sigma 18-50mm f2.8 EX DC was pretty unreliable on it, focusing-wise. Which made me always hit the shutter button half way 2 or 3 times, till the  focus looked ok. Later, on my 450D, the Sigma focussed just fine. The other way around with my Tokina 12-244mm f4. On the 350D, it was fine. On my 450D, the Tokina could not hit focus well at all, behind or in front of the subject was the norm. 

 

In live view, the Sigma was not reliable, and the Tokina just laughable. 

 

So, yeah... Just one thing you can do: get the lens calibrated with the body, and hope that they do a competent job.

[Arthur Macmillan]

It's revealing that you say the lens is not focusing on one camera only, and not the camera is having problems with one lens only.  I'm guessing you have more lenses then cameras.  What Brightcolors recommends is the most sure way to get the problem resolved.  On the other hand I think there is some merit to sending the lens back if is not working right, and hold on to your camera.  If it still under warranty...


This is a lens that has a reputation for focus breathing which is not always easy to detect if you only test it wide open.  There is bound to be variation in lens quality.  So, I suppose you could have them adjust it to work on your particular camera body.  That is a sure fire solution.  I'm tempted to think the lens is just off, and let them fix it the old fashioned way.  This might not make sense, but to me, they need to give you a lens that meets your expectations.  You might be too used to lenses like "even your 50, f/1.4" and presumably better.  You may have reached the elite level where this lens simply is not going to be good enough for you.  Sharp and fast, but only if it feels like focusing. 

 

Just saying.