Infrared wavelength and visual quality of simple lenses:

A:720nm or 680nm, 665650nm, or the following, cloudy or facing the common brightness of the TV can see the red light.

B:760nm, in front of a 40 Watt household light bulb can see the light bulbs in the near segment of the very light goods. Facing the 20 Watt energy-saving lamps can be found very dark and light tubes.

C:850nm against 40 Watt household lighting can see filament lamp. In front of a 20 Watt energy-saving lamp is almost can not see anything to, if you can see a lamp for secondary leaky lens.

D:950nm almost invisible to the 40 Watt light bulbs.