While I now understand how to do the math to properly select suitable lenses based upon their diameter and focal length, one part I do not yet understand is how lens diameter and focal length translate into effective range (given all other variables being equal). For instance, I know that a larger lens with a longer suitable focal length will give you longer range; I just canâ€™t predict how *much* longer range. Is there a formula that I can use to predict the efficiency of a lens of a particular diameter and focal length?