Vertigo effect for Maya

vertigo.py

import pymel.core as pm
import math

listLens = [8, 12, 24, 35, 50, 80, 135 ]
cam = pm.ls( pm.PyNode(pm.modelPanel(pm.getPanel(wf = True), q = True, cam = True)) )[0] # Getr current viewport as camera
#cam = pm.ls( pm.PyNode('camera1') )[0] # Getr current viewport as camera
camFL = cam.focalLength.get()    
camCI = cam.centerOfInterest.get()
camHFA = round(25.4*cam.cameraAperture.horizontalFilmAperture.get()) # Camera Aperture (mm)
camA = round(cam.getHorizontalFieldOfView()) # Camera Angle of view
camB = 2 * camCI / (math.tan( (math.radians(180-camA)/2)) ) # object size (bottom of camera triangle)

# LOCK ACTIVE CAMERA
def lockCam(cam):
    if (cam.tx.get(l=1) == 1):
            cam.translate.set(l = 0)
            cam.rotate.set(l = 0) 
    else:
            cam.translate.set(l = 1)  
            cam.rotate.set(l = 1) 

def vertigo(camFL):
    camA = round( math.degrees( 2*math.atan( camHFA/(2*camFL) ) ) )
    distance = camB/2 * ( math.tan( math.radians((180-camA)/2)) )
    pm.dolly( cam, abs = 1, d = distance )
    cam.focalLength.set(camFL)
    # print 'FL = {0}  DIST = {1} CI = {2} A = {3} B = {4}'. format(camFL, distance, camCI, camA, camB)

     

def baseUI(*args):
    
    if pm.window('vertigo', q = 1, ex = 1):
        pm.deleteUI('vertigo')  
    win = pm.window('vertigo', t = 'DS Vertigo', rtf = True, w = 280 )
    with win:
        mainLayout = pm.columnLayout() 
        
        camLayout = pm.rowColumnLayout(nc = 10, parent = mainLayout)
        for i in listLens:
            LB = pm.button(l = str(i), w = 30, h= 40)
            LB.setCommand(pm.Callback (vertigo, i))
        
        lockCAM = pm.button(l = 'LOCK CAM', w = 70)
        lockCAM.setCommand(pm.Callback (lockCam, cam))

        slidekLayout = pm.rowColumnLayout(nc = 1, parent = mainLayout) 
        zoom = pm.intSliderGrp( min = 5, max = 100, v = camFL , field = 1, step = 1, w = 280, h = 40, dc = vertigo ) 
             
    win.show()  
baseUI()