Interesting issue with Tamron Lenses
I received this information a while back, I didn't post it until there was some kind of response from Tamron.

The following is a direct quote from the folks that found the problem. Tamron's response is at the bottom.
i am a member of the german dslr-forum (, which is probably the biggest german speaking community regarding all DSLR-topics (not only Canon). We observed a phenomenon where the followings lenses won't use the outer cross-type sensors of EOS 40/50/60/7D cameras right.

The lenses that show this problem are (all Tamron):

  • 17-50 f/2.8 VC
  • 60 f/2 Macro
  • 70-200 f/2.8
  • 10-24 f/3.5-4.5

To get a bit more into the detail of the problem – on the 40/50/60D cameras the outer cross-type sensors only work as line-type sensors. To be a bit more correct, they actually work in the same direction as they would work on cams like the 30D or like the 400/450/500/550D. When it comes to the 7D the outer sensors are also only working as line-type sensors (but it seems, that the EF 50 1.2L also has problems to use them correct).

The center cross-type sensor does work at least as a single-cross type sensor (infact we don't now how to test if the center sensor is working as a dual-cross-type sensor like it's supposed to work with those f/2.8 and better lenses).

Tamron seems to not know about this behaviour so far. Well – at least, they didn't confirmed the problem and only said, that they will investigate this.

Maybe a small addition – the Tamron 17-50 VC uses the same lens-ID as the EF 35-80 – maybe you'll have the chance to check whether this Canon-lens performs correctly or not.

The link to the thread is:

Tamron Europe's Official Response
Dear Mr. S.,

we were able to reproduce the situation where the Tamron 17-50 VC (B005) and the Tamron 60 Macro (G005) won't use the Canon EOS 50D cross-type sensors correctly.

We have given this information to Tamron in Japan and we are expect an answer very soon.

Best regards
Tamron Europe GmbH

Thanks Joerg


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