How to change ray angle of inclination

Hi Guys! I have a little problem. I want to do little bit more realistic shots. When i have a ray from main camera then shot is going in a straight line. I want to do ray angle but i dont know how. I tried with quaternions but i think this isn’t good solution. Can you help me please?

PS. I dont want bend ray.

Vector3 forward = this.transform.forward;
forward = Quaternion.AngleAxis(45, Vector3.up) * forward;

Use this as your forward Vector3 when doing the raycast.