Shutter Shock a myth

Started Jan 1, 2014 | Discussions thread
DavieK Contributing Member • Posts: 705
Re: It's not a myth, it's just that..

I've checked the shock using seismographic apps on the iPhone, and it has a duration of roughly 5ms (1/200th) peak, occurring at the very start of the exposure. So with 1/100th which is the worst setting for this, half the exposure can be jolted to a slightly offset position - and indeed, that's exactly what tests show. At 1/50th, only a quarter of the exposure is affected so it appears less strong and at 1/25th it's just a very faint shadow.. At 1/200th the entire exposure is over and complete within the peak of the shock displacement (if any - remember that different lenses, different tripods, different ways of gripping and supporting the camera will all have an effect and I can generally guarantee a sharp result at any shutter speed with my 40mm Nokton, for example).

The lenses you tested do not have stabilisation. The odd effect of this shock is that it seems to be transmitted to the lens and to hit the stabilisation sensor in the lens at just the wrong phase, making it react in the wrong direction or when not needed. The shake itself may have no effect at all, but causes a blip in the IS/OS which creates shake even when there was none. This seems to be the case with my 70-300mm Sigma OS, seemed to affect the 18-200mm Tamron VC, but does not affect the 28-70mm FE and the 10-18mm E - both of which are enabled for OSS on the A7R by Sony, and presumably have been tested and found to be OK.

In short, the shock is not a myth but it also is not some kind of guarantee of camera shake any more than a mirror action is a guarantee of camera shake. I think there is a very specific technical issue which affects IS/OS lenses, and a straightforward shake issue which affects longer lenses when mounted a certain way on specific tripod heads.

All I have to do to avoid the shake on my 70-300mm Sig OS in turn the OS off and follow normal hand-holding guidelines. But I'd like it if the OS worked, and I know there are some Canon IS users with adaptors able to power the IS who have found exactly the same. And we know that Sony has disabled OSS in lenses like the 55-210mm where it would be very useful.


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