Smoothly changing orbit distance

Say I'm orbiting a player by calling:

%observer.setOrbitMode(%targetObj, %transform, %min_distance, %max_distance, %arg4);

but then want to orbit him at a different max_distance. At the moment I simply call:

%observer.setOrbitMode(%targetObj, %transform, %min_distance, %ne_max_distance, %arg4);

However, this causes a nasty jump. Has anyone got any ideas on how to do this smoothly?

Cheers,
Ian