One of the attributes of Cuddeback is that it is super easy and cheap to change out the Fresnel lens. It gets the least consideration but it is the most important aspect of the camera and the least expensive to change out. It is made of some form of plastic that will degrade from UV damage in time. I suppose set in direct sunlight the degradation will be greatly accelerated. It doesn't take much to affect the refraction of an IR wavelength through the Fresnel lens. The Fresnel lens is trying to focally center the IR onto one half of the sensor. If Fresnel lens is degraded by sun, pollen, dirt, water spots, scratches, etc it can greatly affect the sensitivity. I am guilty of leaving camera up when bush hogging, plowing, and planting. Anyways, give this a thought when troubleshooting detection issues.