This is mostly for shallow water anglers 60ft and less, all transducers that run 200hz (+ - 10hz) have basicly the same angle, typically divide the depth your at by 3. That number is how wide your cone is at the bottom as it tapers to a fine cone at your transducer. Folks use 200/83, 200/50 for the most part. The wider cone is used mostly to watch cannonballs etc while trolling or if your running 2 transducers and don't want them to interfer with each other. Side imaging is another beast and unless your going to move into using one, not required for the questions asked. Fish that are high in the water column usually do not get marked as they tend to move away from your boat.