image moves on hover – chrome opacity issue
Another solution would be to use -webkit-backface-visibility: hidden; on the hover element that has the opacity. Backface-visibility relates to transform, so @Beskow‘s has got something to do with it. Since it is a webkit specific problem you only need to specify the backface-visibility for webkit. There are other vendor prefixes. See http://css-tricks.com/almanac/properties/b/backface-visibility/ for more info.