Black vs white Fresnel lens

Maker, DIY
1

Hi,

I am working on a budget trail camera and am using a classic HC-SR501 PIR sensor. However, I’m getting a lot of false triggers, mostly coming from cloud and tree shadows changing during daytime. The sensor works great during night time.

Trail cameras use black Fresnel lens for their PIR sensor. I took a cheap one (that works pretty well) apart to find this LHI 968 / 3866 Excelitas Technologies | Sensors, Transducers | DigiKey. It uses a flat black Fresnel lens.

Is it better to use a black Fresnel lens to prevent false triggers?

PC

2

Hello prithulc,

Thank you for posting on the TechForum.

I’m not an expert on this but from what I found doing some research on this the black Fresnal lens does help considerably, but it’s not going to be perfect.

1 Like
3

Hi Jeff, thanks for your insight!

I might give it a shot. Do you have any blog/document/resource that you can share in this regard?

PC

4

Here is a couple links on this.