E-P5 and "shtter Shock"

Started Oct 6, 2013 | Discussions thread
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Anders W Forum Pro • Posts: 21,465
Re: A relevant question...

lester11 wrote:

Anders W wrote:

Judging by his report, Lester appears to think that you can put an equal sign between shutter shock and double contours. I don't. Ordinary camera shake can give rise to double contours too and shutter shock can manifest itself without.

Hi Anders

My first objective was to obtain reproducible shutter shock. That is, indisputable visual evidence that would survive the rigours of, erm, forum review. The first step was to define shutter shock (for my purposes) in a way that meant it could not be dismissed as just some kind of perfectly familiar blur or camera shake by a sceptical reader. I thought there would be little point joining the discussion here with a blurred image and attempting to claim evidence of shutter shock (smile).

Furthermore, it is unclear to me whether he realizes the need to consider things from a statistical point of view and has tested accordingly.

In one of my other lives I am an experimental statistician (smile). But I want to avoid a stochastic analysis and associated data for as long as possible. Instead, I want to demonstrate a reproducible "something" -- shutter shock -- at every instance, so that it could not be dismissed as some kind of artefact (I guess I am repeating myself here) by a sceptical reader. Not that I am knocking scepticism, it is a necessary attribute of a successful experimenter, but there are a couple of enthusiastically loud sceptics here whose noise can drown signal...

Finally, I find no reason to think that the shutter speed at which the problem peaks should be strongly affected by whether the grip (and its additional weight) is attached or not. While I think a lot might depend on personal variation, the point at which the problem peaks is not among them.

So I'm just starting a journey you have travelled well. Nevertheless it is not yet clear to me that the problem I'm working on (double image ghosting in one dimension in the E-M5 and E-PL3) is independent of shutter speed. Instead (to my surprise) I have found adding the grip is a factor which I have yet to analyse further. It could be the additional mass. It could be the different pivot point (ie different rotational impulse) offered by portrait instead of landscape orientation when the camera is held only in a crooked right hand.

Hi Lester,

While I appreciate your efforts to help out with the testing, it is regrettably not possible to determine, with certainty, the presence or absence of shutter shock by the presence or absence of double contours. Such contours may accompany shutter shock but not always do. Similarly, double contours can appear as a result of camera shake not produced by the shutter.

Since the impact of shutter shock as well as other sources of blur vary on a shot-to-shot basis it is additionally impossible to bypass the need for statistical testing. In other words, you need to shoot quite a few images under the two (or more) conditions you wish to compare, not just a single one.

Since checking lots of and lots of shots for sharpness is tedious and time-consuming, it is additionally important to use a target that allows you to tell, quickly as well as reliably, how good or bad a certain shot is with regard to sharpness. Here's an example of a good target, similar to the one I have used in my own testing. The print screen structure is very effective in revealing even the slightest amount of blur.


When testing for vertical as opposed to horizontal blur, however, you might want to use a grid of some kind or some other target with vertical as well as horizontal lines, such as the one used here:


As to shutter speed, neither I nor anyone else is saying that the problem is independent of shutter speed. On the contrary, it is well known by now that the problem peaks at about 1/125 s (give or take 1/3 EV) and gradually declines on either side of the peak.

Adding a grip is likely to reduce (but not eliminate) the impact of shutter shock due to adding weight at a suitable location (right below the shutter).

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