Quote Originally Posted by jsimoespedro View Post

There is no evidence that the mirror vibration was fully damped by the time the shutter opened.
But I can agree to disagree .
It's possible to tell that the action of the mirror is evident, and that the amplitude degradation as the mirror vibration settles is also evident, regardless of whether shutter vibration is taken into account or not. Since shutter vibration cannot be entirely eliminated anyway, it is a moot point to discuss. It's there, whether we flip up the mirror or not, so it's a constant, not a variable.

The point is that the the vibration that is likely cause mostly due to the mirror action, is not fully damped by the time the shutter opens.
- If a tripod with poor vibration damping, or poor vibration draining abilities is used, there will be more vibration in the camera itself, causing unsharp pictures, and that there are some shutter times that are particularly sensitive to this, where vibration is sustained during a majority of the lapsed time.
- If the camera is hand held, the photographer must employ techniques to hold the camera as still as possible.