scripting - zoom camera to view all objects

Question

My objects sounds like a bit large, I guess I need to move camera far away from origin (put a sphere there) but if I increase the camera location x value, it will can not see anything.

import bpy
from math import radians,cos,sin,tan
from mathutils import Matrix, Vector, Euler

def clean_objects():
    if len(bpy.data.objects) == 0:
        return
    oldMode = bpy.context.mode
    if oldMode != 'OBJECT':
        bpy.ops.object.mode_set(mode='OBJECT')

    for o in bpy.data.objects:
        if o.type == 'MESH':
            o.select = True
        else:
            o.select = False
        o.select = True
        #print("%s -> %d"%(o.name,o.select))

    bpy.ops.object.delete()
    if oldMode != 'OBJECT':
        bpy.ops.object.mode_set(mode=oldMode)
    return

def dump_objects():
    for ob in bpy.data.objects:
        print(ob.name)
    return

def setOrigin(loc):
    for ob in bpy.data.objects:
       ob.location -= loc
    return

def add_objects():
    m = 16
    n = 12
    h = 96
    outer = 100
    stud_x = 4
    stud_y = 8
    stud_z = 96
    alpha = 30
    for i in range(0,m):
        print(i)
        for j in range(0,n):
            if (i == 0 or i== m-1 or j == 0 or j == n-1):
                bpy.ops.mesh.primitive_cube_add()
                bpy.context.object.dimensions = (stud_x,stud_y,h)
                bpy.context.object.location = (16*i,16*j,0)

    bpy.ops.mesh.primitive_cube_add()
    bpy.context.object.dimensions = ((m-1)*16 + stud_x,stud_y,stud_x)
    bpy.context.object.location = ((m-1)*16/2,0,(h+stud_x)/2)   
    bpy.ops.mesh.primitive_cube_add()
    bpy.context.object.dimensions = ((m-1)*16 + stud_x,stud_y,stud_x)
    bpy.context.object.location = ((m-1)*16/2,(n-1)*16,(h+stud_x)/2)   
    bpy.ops.mesh.primitive_cube_add()
    bpy.context.object.dimensions = (stud_x,(n-1)*16,stud_x) # overlap
    bpy.context.object.location = (0,(n-1)*16/2,(h+stud_x)/2)   
    bpy.ops.mesh.primitive_cube_add()
    bpy.context.object.dimensions = (stud_x,(n-1)*16,stud_x) # overlap
    bpy.context.object.location = ((m-1)*16,(n-1)*16/2,(h+stud_x)/2)  

    for i in range(0,m):
        bpy.ops.mesh.primitive_cube_add()
        bpy.context.object.dimensions = (stud_x,(n-1)*16+2*outer,stud_x)
        bpy.context.object.location = (16*i,(n-1)*16/2,(h+stud_x)/2+stud_x)  

        p = outer + (n-1)*16/2
        bpy.ops.mesh.primitive_cube_add()
        bpy.context.object.dimensions = (stud_x,p/cos(radians(alpha)),stud_x)
        bpy.context.object.location = (16*i,p/2 -outer,(h+stud_x)/2+stud_x + p*tan(radians(alpha))/2)  
        bpy.context.object.rotation_euler = (radians(alpha),0,0) 
        bpy.ops.mesh.primitive_cube_add()
        bpy.context.object.dimensions = (stud_x,p/cos(radians(alpha)),stud_x)
        bpy.context.object.location = (16*i,p/2 -outer + p,(h+stud_x)/2+stud_x + p*tan(radians(alpha))/2)  
        bpy.context.object.rotation_euler = (radians(180-alpha),0,0) 
    bpy.ops.mesh.primitive_plane_add()
    bpy.context.object.dimensions = (16*(m+5),16*(n+5),10)
    bpy.context.object.location = (16*m/2,16*n/2,-h/2)
    setOrigin(Vector(((m-1)*16/2, (n-1)*16/2, h/2)))    
    return

def add_camera():
    bpy.ops.object.camera_add()
    bpy.context.object.location = (150,50,150)
    bpy.ops.object.lamp_add(type='SPOT')
    bpy.context.object.location = (200,200,200)
    bpy.context.object.dimensions = (200,200,200)
    bpy.ops.curve.primitive_bezier_circle_add(radius=400)

    camera = bpy.data.objects['Camera']
    path = bpy.data.objects['BezierCircle']
    lamp = bpy.data.objects['Spot']

    camera.select = True
    lamp.select = True
    path.select = True

    bpy.context.scene.objects.active = path #parent
    bpy.ops.object.parent_set(type='FOLLOW') #follow path

    bpy.ops.mesh.primitive_uv_sphere_add(size=20, location=(0,0,0))
    target = bpy.context.object;
    camera.constraints.new(type='TRACK_TO').target = target
    camera.constraints["Track To"].track_axis = 'TRACK_NEGATIVE_Z'
    camera.constraints["Track To"].up_axis = 'UP_Y'
    bpy.context.scene.camera = camera

    for area in bpy.context.screen.areas:
        if area.type == 'VIEW_3D':
            area.spaces[0].region_3d.view_perspective = 'CAMERA'
            break            
    return

def select_objects():
    for ob in bpy.context.scene.objects:
        ob.select = False
    for ob in bpy.context.visible_objects:
        ob.select = True
    return
#-----------------------------------------
clean_objects()
add_objects()
add_camera()

I guess "track to" feature should be able to adjust the angle of camera, how can I adjust my camera parameter to view full objects?