[NorthMountain]

The visible spectrum is from 390nm to 750nm, a range of 360nm.

These lenses work in the near infrared, from 1200nm to 1700nm, a range of 500nm. That is a bandwidth somewhat GREATER than the visible spectrum.

[Steely Tom]

The visible spectrum is from 390nm to 750nm, a range of 360nm.

These lenses work in the near infrared, from 1200nm to 1700nm, a range of 500nm. That is a bandwidth somewhat GREATER than the visible spectrum.

That's true, but the difficulty lies in getting a given bandwidth as a percentage of center wavelength.

500 nm bandwidth with a center of 1450 nm is a lot easier than 360 nm bandwidth with a center of 570 nm.