Photosensor Hood

I wanted to make my outside lights turn on at dusk and off at dawn so I added a photosensor. I ended up with a problem where the light coming on and dusk would cast light on the sensor causing it to go back off. This cycle would continue every 30 seconds. I needed a hood that would allow sunlight to hit the sensor but would shield the sensor from the light of the lamp. After four tries I came up with this hood which works and is adjustable by twisting it. The 17mm inside diameter of this hood fi