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12-21-2012, 04:35 AM   #1
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sigma 17-50 parfocal?

I have just purchased used 17-50 sigma ex hsm 2.8 and have noticed that it changes focus when zooming. Is this normal for this lens. Also I thought hsm was supposed to be silent but I can hear noise when it focuses.

Last edited by everydaylife; 12-21-2012 at 05:08 AM.
12-21-2012, 11:40 AM   #2
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It is ok. After researching the internet I have found that the lens is varifocal and that there is some gear noise when it focuses. Panic over.

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