There is a good article in TDP on minimum shutter speeds and focal length of lenses.
http://www.the-digital-picture.com/News/News-Post.aspx?News=17252
The author is basically right that pixel size is the key factor, and argues and experiments that 1/2*f is a better working rule than 1/1.6*f for APS-C and 5DS/R.
http://www.the-digital-picture.com/News/News-Post.aspx?News=17252
The author is basically right that pixel size is the key factor, and argues and experiments that 1/2*f is a better working rule than 1/1.6*f for APS-C and 5DS/R.