vtkRenderer::ResetCamera reset the view angle
vtkRenderer::ResetCamera intentionally set the View Angle at 30 :
https://gitlab.kitware.com/vtk/vtk/-/blob/master/Rendering/Core/vtkRenderer.cxx#L1099
// Reset the perspective zoom factors, otherwise subsequent zooms will cause
// the view angle to become very small and cause bad depth sorting.
this->ActiveCamera->SetViewAngle(30.0);
This comment does not seem to make sense to me, zooming/unzooming is done via a dolly, not via changing the view angle. So this call should be removed imo.
@allisonvacanti : You wrote this in 2013, so if you remember, that would be great.