I bought this solar powered wifi camera. I stuck it in a tree above my front gate, hoping to automatically trigger to record vehicles and people in front of it. The footage uploads to the web, via my wifi network.

Whilst the video quality is fine and uploading works, the PIR detection range is inadequate. They claim 10 meters, but I reckon its less than that.

Would it be straightforward to extend the PIR range to say 25 or 30 meters by sticking a lens in front of what's there already (a fresnel lense)?

I understand the extra lens would need to be transparent to infrared.

Edit 22/11

Found these lenses. I'll give them a try. The page includes a helpful guide to selecting the right lens:

enter image description here

  • \$\begingroup\$ The appears to be about modification of a product's passive infra-red sensor (to improve detection range) and not really about photography. If that's accurate, then I think this is off-topic for Photography StackExchange. Also, the PIR sensor and the camera's lens are two different components. Changing a camera's lens (assuming it uses CS mount lenses ... I didn't see a mention of the lens-mount type on the security camera page) wouldn't change the PIR sensor. \$\endgroup\$ Nov 22, 2020 at 16:56
  • \$\begingroup\$ I don't see how this question applies to photography, per se. It seems to be about some type of motion detection or machine vision application. \$\endgroup\$
    – xiota
    Jan 21, 2021 at 17:51

1 Answer 1


The angle of vision isn't everything. If your camera sensor doesn't receive enough IR, changing the angle of vision will not change that. The important factor is the "aperture" of the lens, usually noted as f/3.0. The smaller the number the more light the lens can collect. A f/2.8 lens collects twice the light of a f/4.0 one ((4/2.8) squared is about 2).


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.