E-P5 and "shtter Shock"

Started Oct 6, 2013 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: E-P5 and "shtter Shock"

Simon Cowell wrote:

Anders W wrote:

Simon Cowell wrote:

Hmm, a counter argument might be that "the inability of IBIS to simply hold the sensor in place with sufficient rigor" could still produce some shake but which is within the safe bounds of OIS (and that's why you get less blur).

How would you define the "safe bounds of OIS"?

Simply as the frequency range of movement that the Panasonic OIS can effectively apply corrections for. You cannot exclude the possibility that this may happen.

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.

After all, the double image effect that we see in the images posted here do not show a very high level of blur, it's the kind of blur that one might associate with subtle camera movement.

I think that apart from mechanical vibrations,

We have evidence (via the experiment described below but also via the investigation reported here


section 4.2) that the blur due to shutter-shock is not a matter vibration but of brute extraneous movement. Shock, pure and simple.

Maybe my definition of vibration is different and perhaps more general than yours as I would consider vibration almost anything relating to movement.

It is important to distinguish between shock (i.e., a non-oscillating movement implying a displacement of the camera as a whole) and vibration (an oscillating movement which doesn't imply a displacement of the camera as a whole) as the immediate cause of the blur inasmuch as our ability to limit the two, and the means whereby we can do it, differ. For example, shooting from a heavy tripod will do nothing to limit the blur if it is due to internal camera vibrations. If, by contrast, it is due to shock, the tripod will help a whole lot.

In any case, I did not go through that page last as I thought it was about a different camera (Pentax) with perhaps a completely different IBIS. However, it seems to be quite relevant and I hope I'm not breaching any copyright by repeating part of section 4.2 here:

"Finding #6: The extraneous blur is not caused by a bell vibration effect. It is caused as a result of extraneous body movement during the exposure.

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.

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.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +28 more
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