In narrowing down my final move (a side grade perhaps as much as an upgrade) from my GX1 to either the Panasonic GX7 or to one of the Olympus E-Ms, the three elements of difference among the choice between the GX7 and the correct one, if any, among the E-M10, E-5 or E-M1 are the viewfinder(s), especially with eyeglasses; the IS capabilities of all the bodies, and what I now am confident is my first priority: the ease or even possibility of back-button or “AF-on” focusing with my final selection. I must admit, as a Nikon DSLR user, that my muscle memory has been trained for back-button focusing, and that I’ve practiced and continually tried to train my synapses for the half-press focus…shutter release without success. This exercise was accomplished quite easily with my GF1 and continues with the GX1. What is not clear to me is whether back-button focus is really even possible with any of the Olympus E-Ms and is at the same time compatible with the excellent Olympus IS process. I have one posting on another forum, i.e., the one that prohibits this M43 forum’s links from publication in postings on that other forum, that states definitely that the two processes are incompatible on the E-M bodies and that the Olympus IBIS will only function with the half-shutter-press method of achieving focus, then releasing the shutter. I think I understand that there are potentially two times in the shooting process when IBIS may be actuated: 1) when viewing through the viewfinder the focusing of the lens, and 2) when actually releasing the shutter. Is it true that neither part of the back-button focus-shoot process on the E-Ms (neither while focusing the lens as viewed through the viewfinder nor at the time of execution of the shot with the shutter release) will actuate the IBIS? Or will the IBIS be actuated upon one or both of the two elements of the focus-shoot process? The newer Nikon DSLR bodies can actuate Nikon’s lens-based IS “VR” at AF-on or back-button, the older bodies just at shutter release. Which, if either, process actuates Olympus IBIS when back-button focusing is in use, or are these processes wholly incompatible?