Quote Originally Posted by zumbido View Post
That video is silly for a number of reasons. Ask a physics teacher if you're interested. Suffice to say that many, many real-world photo tests have demonstrated that it does matter, for certain (but not all) common conditions. These are extremely easy to find online if you don't feel like going to the library ... google things like "mirror lock-up test".
I post the video because I get tired of seeing posts claiming that a Hasselblad with a 80mm lens or a Nikon SLR with at 50mm lens, both so called normal lenses, cannot be hand held for shutter speed of 1/60 seconds. Which is a bunch of $#!+. Normal body motion, limit cycling, from breathing to the heart pumping cause more motion than the so called mirror slap. Claims that an RF can be hand held for 1/5 second are also a bunch of $#!+. Below 1/[lens focal length] it becomes necessary to use a tripod or set the camera down on a stable surface, some for sooner than others. The duration of mirror slap is so short due to dampening that a 10 second exposure is not going to show any effect, but it may be wise to lock up a mirror on long exposures as a good practice.

If one were to down enough brewskis then at 1/125 or 1/250 seconds one can get blur with either an SLR or RF camera.

Since I have been an engineering professor and technically I am a rocket scientist I will ignore the comment about asking a high school physics teacher posting on line for advice.