I just bought a Canon Ftb at auction and it came with a 55mm f/1.2 lens. The lens is in excellent condition and the glass looks perfect. There is a yellow tint to the front element. I am curious if this is the coating or if it might be yellowing similar to some of the old Pentax Takumars? When looking through the lens there is no noticeable tint, which makes me think it might be the coating. Thanks.