On my Sigma 17-70mm f/2,8-4 DC MAKRO OS HSM, I have the impression that the image stabilizer (OS) is broken. If I switch it on, I can see no difference when I look through the camera, the slight movements from me not holding the camera steady are visible in the viewfinder. To me it looks the same as when the OS is switched off.

This is completely different on my Canon EF 70-200mm f/2.8L IS USM, which I took as a comparison. There, I can easily see through the viewfinder whether the IS is on or off.

Is there a better way for me to test the working OS of my sigma, apart from looking through the viewfinder of the camera? Or is it possible that the OS is only activated when I press the shutter release?

  • What camera is the Sigma lens attached to?
    – Michael C
    Dec 23, 2013 at 18:28
  • I am using it on a Canon EOS 60D
    – Frank
    Dec 24, 2013 at 9:55

2 Answers 2


Optical Image Stabilization in a lens generally works by having several gyroscopes that rotate at high speed to keep a lens element oriented to counteract movement. These gyroscopes use lots of power and are often only powered up when going to take a photo.

For example, on most Canon camera bodies, if you are shooting through the viewfinder, the gyroscopes only turn on when you half depress the shutter button. It can take a small amount of time for them to spin up and start stabilizing as well. The most reliable test I've seen for visibly seeing the impact is to start shooting video and flip the switch for stabilization on and off. This typically produces the most obvious change for me.

As TFuto mentioned, it's also important to remember that for a given amount of shake, it will be much more noticeable on a longer focal length than a shorter one, so you should try comparing like focal lengths.


Make a shot with stabilizator turned on, and another with turned off, under low light condition, and compare the images - that is the test! :-) It may be that your stabilizer does not want to use battery while you are not making an actual shot.

Also, comparing a -70mm to a -200mm is unfair... camera shake at 70mm can be survived, but makes pretty hard to compose and focus at 200mm, but this is just my opinion.

  • For the comparison, I had both lenses at 70mm of course... But yeah, I will make test shots :-)
    – Frank
    Dec 23, 2013 at 13:05
  • Even though both lenses overlap at 70mm, the IS on the 70-200 is optimized for 200mm, while the IS on the 17-70 may be optimized for anywhere between the middle of the range at around 45mm to around 70mm.
    – Michael C
    Dec 24, 2013 at 13:29

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