Tamron 24-70mm f2.8 VC - Odd AF behavior

bobbykbobbyk Registered Users Posts: 45 Big grins
edited June 17, 2014 in Cameras
I posted something earlier on this lens but now maybe I am wondering if I put away the Canon lens too soon.



I really like the VC capability of my Tamron 24-70. But my percentage of shots that are in focus dropped a bit. So I did a MA cal, using Reikan's FoCal on the lens with my 5DMkIII and got some results that seemed odd to me.
So I went and did a bunch of calibration with the Focal and Lens Align systems with both my Canon and Tamron 24-70's on both my 5DMkII and III.
Here is the long story of my results:
http://www.bobkeenanphoto.com/.../autofocus-af-microadjustment-ma-epiphany/
The short story is that the Tamron MA shifts a fair amount compared to the Canon.
Any thoughts on this? Did I get a bum Tamron?

Comments

  • Brett1000Brett1000 Registered Users Posts: 819 Major grins
    edited June 6, 2012
    bobbyk wrote: »
    I posted something earlier on this lens but now maybe I am wondering if I put away the Canon lens too soon.



    I really like the VC capability of my Tamron 24-70. But my percentage of shots that are in focus dropped a bit. So I did a MA cal, using Reikan's FoCal on the lens with my 5DMkIII and got some results that seemed odd to me.
    So I went and did a bunch of calibration with the Focal and Lens Align systems with both my Canon and Tamron 24-70's on both my 5DMkII and III.
    Here is the long story of my results:
    http://www.bobkeenanphoto.com/.../autofocus-af-microadjustment-ma-epiphany/
    The short story is that the Tamron MA shifts a fair amount compared to the Canon.
    Any thoughts on this? Did I get a bum Tamron?

    I don't know but that's quite an elaborate set of charts and graphs! I've always heard "MA" changes with focal length so the results are iffy on a zoom lens. Somehow I've managed to survive for years without any micro adjusting at all on any of my lens
  • bobbykbobbyk Registered Users Posts: 45 Big grins
    edited June 6, 2012
    Brett1000 wrote: »
    I don't know but that's quite an elaborate set of charts and graphs! I've always heard "MA" changes with focal length so the results are iffy on a zoom lens. Somehow I've managed to survive for years without any micro adjusting at all on any of my lens

    Maybe all this MA stuff is a bit of overkill. I know that on my better Canon lenses the MA adjustment is only in the range of 0-3. Do if you don't do the MA the only issue is that you may be slightly front or back focused. Since there is always variability in the AF , if you take a few shots of the same subject, one will be perfect.

    But for some lenses where the adjustment requires 6-20 MA you may never get a good shot.

    For my Tamron, I am thinking of sending it in to see if Tamron can make this better.
  • scottgee1scottgee1 Registered Users Posts: 230 Major grins
    edited June 17, 2014
    This thread just had its second birthday -- hope it was happy! ;)

    Bobby, what did you end up doing and were you able to resolve the problem?
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