Is this VR malfunction? -- viewfinder image becomes unstable again after a few seconds

Question

I got a factory refurbished Nikon 70-300 mm VR lens a few days ago. At 300 mm the effect of vibration reduction (VR) is clearly visible in the viewfinder. The image becomes stable a second or so after I half-press the shutter button. A few seconds later it becomes unstable again though. (VR doesn't switch off when it becomes unstable, I don't hear the click.)

Is this normal behaviour (i.e. that VR only works for a few seconds)? Is it possible that it's because of my arm getting tired or the wind moving the house slightly, I'm just not noticing it? Most importantly, what is the best objective way to test that VR is working as it should, so I can use the warranty before it expires (if necessary)?

Here are two sample videos, both taken handhold, while supporting my elbows on a railing. The Active-Normal switch was set to Normal.

• Sample video with VR off (23 MB)
• Sample video with VR on (39 MB)

^{If you want to prevent the videos from playing in a plugin (e.g. slow internet), right click the link, then choose Save As...}

I'd appreciate if someone who has the same lens could comment.

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Update:

• Sample video With Active mode (53 MB, looks the same as Normal mode, stable until ~12 s, then shaky)

Update 2:

I found a thread about a similar problem here. There isn't really a conclusion there.

Answer 1

Are you in normal or active mode? It appears to me you are likely in normal. The difference between the two is that in normal, if the camera thinks you are trying to pan, it disengages the stabilization on horizontal movement to prevent the stabilization from fighting the pan and causing movement to lag behind your pan.

In the video with it off, you can see there is constant vertical and horizontal shake. In the video with it on, it turns on, detects what it thinks is an attempt to pan, then the horizontal appears to disengage resulting in lots of left to right shake, but motion up and down still appears to be stabilized.

Try using active mode which should keep both horizontal and vertical stabilization going all the time. If you still have problems, then perhaps one of the gyroscopes in the lens has a fault of some type.