New Sigma 105 Macro - OS noise

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Paul
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So thought I'd take advantage of the recent halving (!) of the price of the Sigma 105mm DG OS Macro lens.

Stuck it on the camera, and although I've yet to use it "properly", just to make sure it all works - straight out the box, when the OS de-activates there's quite an audible "brrrrrrr" just before it stops. Done some Googling and people mention a noise, but reports seem to vary between odd-but-normal for the lens, or send-it-back level of grinding. With nothing to compare it too, I'm not sure which it is.

When the OS is active it hums, but so does my 24-105 L, it's just when it shuts off it chatters a bit. The manual does say to ensure OS is switched off before removing/attaching the lens (which is odd - does everyone else do this?), and when off the camera, there is some rattling when placing the lens on a table or er... shaking it.

Just not sure if this is normal or not before sending it back to WEX.
 
I also just recently purchased this lens from WEX. Mine also makes a noise similar to what you have described when the OS is functioning.
Like you I was going to return it but after Googling it seems to be the norm with this lens.
Mine works perfectly once you get over the OS noise.
 
That's reassuring :)

Does yours also hunt quite a bit (and fail to find focus) at macro distances?
 
To be honest with buying it in winter I have not used a great deal apart from a couple tests (not many insects). I had no problem with close focusing.
I did notice though that sometimes focusing on a more distant object if it was miles out it struggle to focus.
I gave the focus ring a turn to get it about focused then it auto focused fine.
I will run more test when I have time now you mentioned macro focusing just to be sure.
 
Cool - it might just be a case of the really poor (non existant!) light at the moment - particularly drab winter...
 
You don't have to turn the OS off when removing the lens. It just means don't take the lens off when the OS is actually active. It shuts off two seconds after you take your finger off the shutter release.
 
Ah ok, that makes more sense. And it's obvious when it's stopped working as it makes the grinding noise ;)
 
With regards to it hunting for focus at macro distance, it's because basically the lens is not at f2.8 full aperture, it's at f5.6 weirdly enough. Have a look at this thread particularly the focus extension section.
http://www.cambridgeincolour.com/tutorials/macro-lenses.htm
It's a lens I am toying with getting and this is one of the things that came up in my research. Even though you have it set at 2.8 (max aperture whilst focussing unless stopped down with DOF preview button) it automatically stops itself down by doubling the distance from he rear element to the sensor, halving the amount of light available thereby causing difficulty in obtaining focus lock.
I guess the answer is one of those LED ring flash things that gives constant illumination to give it a bit of a boost.
 
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