Stick up cam motion detection distance problem

Our stick up camera (battery, 3rd gen) is only detecting motion up to about 15 feet. I have the setting on maximum. Anything else I can do? Pic of capture example is attached here. (There is a public path at the far back right corner of this image, which is why we would like to be able to detect motion much further, if possible.) Tried to attach pic of our set up too but it will only let new users post one image.