AF point use by Tamron lenses

As Bryan warns in his reviews of 3rd party lenses, since they are reverse-engineered for compatibility, sometimes issues crop up with new - or in this case old and new - Canon bodies. Cross-posting from a new post over at CR:

Quote:

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Originally Posted by CRGuy

The following is a direct quote from the folks that found the problem. Tamron’sresponseis at the bottom.


i am a member of the german dslr-forum (www.dslr-forum.de), which isprobably the biggest german speaking community regarding all DSLR-topics(not only Canon). We observed a phenomenon where the followings lenseswon’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 40/50/60Dcameras the outer cross-type sensors only work as line-type sensors. Tobe a bit more correct, they actually work in the same direction as theywould work on cams like the 30D or like the 400/450/500/550D. When itcomes to the 7D the outer sensors are also only working as line-typesensors (but it seems, that the EF 50 1.2L also has problems to use themcorrect).


The center cross-type sensor does work at least as a single-cross typesensor (infact we don’t now how to test if the center sensor is workingas a dual-cross-type sensor like it’s supposed to work with those f/2.8and 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 willinvestigate this.


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


The link to the thread is:http://www.dslr-forum.de/showthread.php?t=732360


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-typesensors correctly.


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


Best regards
Tamron Europe GmbH

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Interesting. Thanks for the heads up.

Never experienced that with my 17-50 non-VC. I guess we'll add another reason to pick the non-VC over the VC lens [;)]


Still they are bang for bucks [A]


Ps: whenever I see CR in a thread I'm starting to feel punked...[:|]