Both wired and wireless spy cams can be detected by very sensitive rf detectors or rf sniffers. Pag wireless kasi, youre trying to detect high frequency transmission. Pag wired, youre trying to detect the very low 60Hz and below (ang pagkaka-alam ko ay 15Hz) scan frequency used by the ccd camera to capture the image from the image sensor and lense.
Having both wired and wireless spy cams covered, these rf detectors only work when the spy cams are powered up. How about wired spy cameras that have their power turned on? The above devices like the spyfinder .. the ones that have a hole in the middle is used to detect both wired and wirless spy cams even if turned off as long as these spycams have lenses. The spyfinder detects reflection of light that bounces-off the lenses. All lenses bounce-off light when it hits them.