Theia's image resolution simulator and lens calculator
Theia's lens calculators (more accurately image resolution calculators) let you see what to expect from different lens-camera combinations. The pictures represent the field of view for a given camera-lens combination and the image resolution. You can use these pictures to set expectations for your customer about how far away a license plate can be read or what level of detail can be seen in a person's face.
Theia offers a free smart phone app versions for Android and iPhone as well as a free online version. All versions show a picture that represents the image resolution you can expect from the camera and lens combination as well as a picture showing how wide the field of view is.