How do you know if the IS is broken?

Discussion in 'Canon Lenses' started by ecphoto, Mar 31, 2012.

  1. ecphoto

    ecphoto TPF Noob!

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    I've never owned a lens with IS before.
    I think it may be broken, but I'm not sure. With IS turned on I move the camera a bunch and the same while shooting video and I don't seem to hear anything from the lens except AF and it doesn't seem to compensate for the movement.

    A few days ago I was trying to focus on a fast moving subject and I heard some grinding, it was the first and only time.

    Its the 18-55 IS III kit lens.

    Its a new lens that came with a new camera. Its about a week old.

    I'm not sure what to make of it.

    P.s.
    Should IS be turned off most of the time?


     
  2. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    Newer IS lenses can be very very quite.

    Try turning the camera on the make sure that the IS switch on the lens is set to on then hold down the shutter half way and put your ear to the lens. You should be able to hear a kind of soft whirring noise and that is the IS. Note try to have the lens set to oneshot AF mode so that you won't confuse AF noise for the IS noise.

    Sometimes when pressed the IS will make a louder grinding sound for a very tiny bit, it should not grind constantly.

    As for seeing the effect it will be harder to see on an 18-55mm range lens because handshake isn't as visible at shorter focal lengths as it is with longer lenses. This becomes even harder to see if you've a good shooting posture.

    IS should be used whenever you've a need to use slower than ideal shutter speeds, the rough rule of thumb being:
    Shutter speed = 1 / (focal length of lens*crop factor from 35mm)

    So for an 18-55mm zoom at 55mm on a crop sensor camera body it would be a shutter speed of:
    1/(55*1.6)
    1/88sec which is roughly close to 1/100sec shutter speed.

    Any slower and the IS will start to be having an effect on countering your handholding motions; any faster and its having little to no effect on the shot. For stills work if you're shooting any moving subject you'll have your shutter speed faster than 1/100sec anyway to avoid motion blur from the subject (which IS has no effect upon). For movies if shooting handheld things are slightly different because of the constant recording whilst holding and I'd expect IS to be left on most of the time.

    If you want to see more of its working try some tests at slower shutter speeds with the IS on and off to compare.
     

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