850nm vs 940nm. Which infrared wavelength is better?

Customers often ask Nightfox which wavelength of infrared flashlight is best. We thought we’d write a blog post explaining the differences and advantages of each wavelength of infrared.

Advantages of 850nm

850nm torches will give the best picture, they will have a slightly longer usable range and they are less likely to create blurry images than 940nm torches. 850 gives better pictures because IR cameras are most sensitive to radiation in this wavelength. However, one problem with 850nm light sources is that they give off a visible red glow. The 850nm range is very close to being visible light, the human eye can very slightly perceive this frequency. That means your IR flashlight could have a slight red glow. If you are watching badgers or coyotes in your backyard that might not be a problem, but the red glow from an 850nm torch could give away your location.

Advantages of 940nm

Our customers often use 940nm torches as a “stealth” solution, making it perfect for airsoft and security applications but also for tracking cautious wildlife. In theory the image quality and range is a little bit lower, although you may not notice this. Sometimes when you use 940nm the “colour” of the beam on a night vision unit is slightly more violet, as in the images on this article, whereas it is typically more grey when using an 850nm torch. One thing to be aware of is that there is still a small red glow from 940nm torches although it is significantly reduced compared to an 850nm torch.

Which wavelength is best for spotting wildlife?

Unless your target wildlife would be scared by a red glow, we recommend 850nm torches. Most of our night vision binoculars and night vision goggles have a built in 850nm illuminator.

Which wavelength is best for airsoft?

We recommend 940nm for airsoft, although some of our customers do still use 850nm. One of the downsides of carrying any IR illumination in airsoft is that it gives away your position to other players that are using night vision. Sometimes our users will set up an infrared torch nearby rather than carrying their own illumination, in this situation it doesn’t matter much which wavelength torch you choose to use.

I want to have the option of both frequencies and visible light in my torch!

The Nightfox Spectrum is a torch that can be toggled between 850nm, 940nm and bright visible light. Being able to pack a single torch, rather than three, is perfect for airsoft, hunting or any other night time adventures.