On 2014-10-06 11:39:07 +0000, Don Tuttle said:

In article , android
wrote:

In article ,
Don Tuttle wrote:

Purchased Tamron AFF004S700 SP 90MM F/2.8 DI Macro Lens for Sony Alpha
Camera. First put it on Sony A77. Auto focus fine for about 20 shots,
then AF stopped working. Turned camera off & on, re-seated lens, AF
still didn't work. Put lens on A65. AF would not work. Turned AF off
and on, messed with miscellaneous things (don't remember what), AF
started working again. Took 22 pics, then AF stopped working. Tried all
previous actions but AF will now not work on either camera.

Does auto focus failure sound like faulty unit or could operator error
or inability be the cause?

Is it a new or used item? If it's new then send it back.

Brand new. Thx for advice. Although I have not read of anyone else
having this problem, I am now spooked re Tamron and am thinking of
getting Sigma 105mm F2.8 EX DG OS HSM, which gets good comments on this
site and elsewhere.
Don

I don't want to spoil the party but why don't you pony up for the
genuine Sony brand macro lens? Another option is to get a nice manual
focus lens - autofocus isn't that great for macro, and AF macro lenses
have a very short portion of the focusing helicoid devoted to longer
distances, making autofocus less precise as the subject distances
increases. I believe several mount adapters are available for the Sony.

I believe that camera manufacturers take active measures to ensure that
their cameras work "best" with their own lenses, and I also think that
Sigma and Tamron are both very bodget oriented (if you get my drift)
with the exception of the lenses at the very top of their lines, which
cost about the same as the camera manufacturer's lenses.