Figure widget camera FOV and figure camera traits aren't consistent

[owenlamont]

I noticed when setting the figure widget camera FOV with the following code (which does seem to work):

import ipyvolume as ipv
fig = ipv.figure(camera_fov=30.0)
ipv.show()
print(f"{fig.camera_fov}, {fig.camera.traits}")

The camera traits for the same figure widget show a different FOV.

Is this inconsistency a bug or are these FOVs different?

I'm using the Anaconda installs on MacOS with the following versions:

ipyvolume 0.5.1
pythreejs 2.0.2
Python 3.7.1