Olympus has added a new focus peaking feature on the Olympus OM-D E-M1 that was not on the predecessor E-M5 model. Focus Peaking is a feature that highlights the area of the composition that is currently in focus.
Focus peaking can help out a great deal while manually focusing an image. However, focus peaking doesn't seem to work when using lenses from other camera systems that are manual focus only on the OM-D E-M1. I tested a Canon 100mm Macro lens with a Rainbow Imaging adapter and focus peaking did not work.
On the Olympus OM-D E-M1, focus peaking can be invoked by turning on "Peaking" in the Gear Menu –> AF/MF –> MF Assist. I configured the Fn2 button on top of the camera to be able to more easily access the focus peaking function.
In the Gear D submenu you can also change the focus peaking highlight color to black instead of white. This is a nice feature if the peaking color is the same as the subject you are trying to focus. Focus peaking can be used both on the viewfinder and the LCD screen.
Overall, I did find focus peaking on the Olympus OM-D E-M1 convenient, accurate, and easy to use. Focus peaking worked better in non macro situations. When shooting macros, the peaking highlights seemed more sparse and were difficult to distinguish. When using magnification on a macro with focus peaking, I had a difficult time telling the static from the peaking.