E-P5 and "shtter Shock"

Started 9 months ago | Discussions thread
Anders W
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Re: E-P5 and "shtter Shock"
In reply to Simon Cowell, 9 months ago

Simon Cowell wrote:

Anders W wrote:

OK. But even if the Panasonic OIS worked perfectly, that wouldn't help if the sensor moved uncontrollably. The OIS system doesn't expect and can't even know about any sensor movement. It assumes the sensor to stay perfectly put and if it doesn't, you'd see significant blur even if the OIS worked perfectly. Hence, the fact that the OIS on the 14-45 reduces the blur to a significant extent indicates that uncontrollable sensor movement (due to the magnets not being able to hold the sensor rigidly in place) is not a factor or at least not a major factor.

OK, I get it, this reasoning sounds plausible. But have you thought about the possibility that the shutter causes a shock to the whole body including the lens and this is what makes the OIS work?

Sure. That's exactly what I think happens.

The vibration/shock (call it any way you want) may cause proportionally more uncontrollable movement to the sensor if the IBIS is unable to rigidly stabilize the sensor. And this may explain why using an OIS lens may reduce the blur but not completely eliminate it. All hypothetical of course.

No that wouldn't explain it. This is exactly the scenario we've already talked about. The OIS accounts for the shock and provided that the sensor stays put, the image is fine. If the sensor wouldn't stay put, the result would be blurred even if OIS did the job right.

That's the really important point here.

Note: this finding does not rule out a vibrating imaging board (which the SR module is mounted onto) where vibration is stimulated by body movement rather than frame vibration. Therefore, whenever we consider vibration of the image sensor in the following, it could be caused by mechanical vibration of the imaging board too."

I think his note may be relevant to E-P5 as you cannot exclude the possibility of sensor vibrations due to shutter movement. And in his summary in section 6 he emphasizes a similar point:

"In the case of the Pentax K-7 camera, the shutter accelarations are a bit high and its floating sensor must then slip by a small amount (which isn't a bad thing as it counteracts the body movement due to shutter operation). But as a result of this, the camera electronics may struggle to get the floating sensor back into tight control. Or the imaging board may swing a little bit. Either effect magnifies blur to a level that it may become visible to the naked eye."

Actually I find his work nothing short of amazing but in my view (a) it does not explain clearly whether the phenomenon is 100% reproducible,

Exactly what phenomenon are you talking about here? I think it is perfectly clear that the blur isn't 100 percent reproducible on a shot-to-shot basis. Therefore, this test (as well as any other reasonably good one) has to work with samples of shots rather than individual ones.

Of course, the more samples the better, but since a digital camera is an electronic device (or micro-electro-mechanical one) don't you think the blur should be reproducible even after taking into account some error tolerances and copy-to-copy variations?

In hand-held shooting, absolutely not. In tripod-based shooting, the variation would be significantly smaller but still there to at least some extent.

and (b) it leaves the explanation open to two interpretations i.e. either inability of IBIS to get the sensor back in control or the sensor swinging. That's why I think that testing may need specialized equipment.

The explanation of precisely what? I can't really follow your reasoning here.

Simply the explanation as to why you might get blurred images at speeds 1/80 to 1/250 even with a tripod. Isn't that the whole point? Of course we can devise a very general explanation: the IBIS (or shutter) is to blame. But it wouldn't be enough, would it?

In the test of Falk Lumo that I linked to, there is virtually no blur at these shutter speeds when the camera is placed on a heavy tripod (see section 4.2, the one I already referred to). I don't have such a tripod to test with but get the same result when placing the camera on something still heavier and rigid: a concrete floor.

So what is left to explain?

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