Isn't this a new feature?
Not really. At least on the OM-3, the CP button is a faster way to enable the computational photography features than selecting the items in the menu separately. The CP features are:
- High resolution
- Focus stacking
- ND filter simulation
- HDR1/HDR2 (and)
- Multiple exposure
With the exception of hand held high resolution mode, I believe the OM-5 supported all of the CP modes that the OM-5 mark II does. The OM-5 mark I did support tripod high resolution mode.
Hmm, none of the manuals that I checked list which lenses can be used for focus stacking. Instead, you have to go to the web site to see what lenses are supported. I imagine the same lenses are supported.