Thread: Night vision 850nm vs 940nm

I believe that technically, no, 850nm doesn't alert animals. But... Whilst my understanding is that no animals (or perhaps it's only mammals?) can see 850nm light, the illuminator doesn't emit 100% pure 850nm light. There's a bit of a bell curve and depending on quality/technology used in the illuminator, a fraction of the light can end up straying into the visible part of the spectrum.

If there is some bleed around into visible red light, it should only be faint. Really faint. Enough that you might catch a lens glowing red in your peripheral vision if you're a lucky deer. But nowhere near enough for deer several tens of metres away to automatically realise that they and the ground they're on are being lit up the moment it's turned on.

So if you have a deer population that is on constant high alert and has learned to associate the sudden appearance of a glowing red blob in the distance with imminent death, it's plausible that an 850nm illuminator might alert them. If they aren't super skittish, and you aren't getting close enough that they are as likely to smell or hear you as see your IR's lens, I think you'll be fine.

I have hunted heaps of wallabies with an 850nm HT-70 and they certainly pay no attention to it. Neither have the red deer I've lit up with 850nm Pards and Sytongs from 20m to 100m. My previous NV scope had a 940nm illuminator and I found the picture got much more noisy (like static interference) much more quickly at distance as the illuminator struggled - it was really only usable past a couple hundred metres on a clear night with a full moon.