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Old 02-18-2013, 07:36 AM
lol lol is offline
L3: Novice
  • Apr 2005
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  • 60 lol will become famous soon enough
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Quote from rustum View Post :
Yah. Focus ring is not smooth. It makes some sound during AF. Sound it makes during live view is a different story. Mine makes very loud sound with Live view focusing (Grinding sort of). I am going to check with Sigma and see if it is expected behavior.
According to Sigma's website, it defines HSM as "HYPER-SONIC MOTOR
This lens uses a motor driven by ultrasonic waves to provide a quiet, high-speed AF." Mine has the same sound intensity levels in both, on and of live views. I have seen here there are many who have the same problem like this. I wonder how Sigma would respond to the question on AF sound if everyone called to ask.