[Chimera-users] Smoothly change level of density map in animation?

Is there any way to alter the density level in a gradual fashion during an animation? I would like to first show the overall envelope of a cryoEM map, and then smoothly change to a higher contour level where I can see helices etc. Many other parameters, such as the presence of a MSMS surface or the position of a clipping plane, seem to automatically gradually transition between two key frames of an animation, but density level doesn’t seem to do so. Oliver.