Grok says below. What is 470nm Photography?. Unlike infrared photography, which reveals unseen light beyond 700nm, this technique stays within the visible spectrum, emphasizing cool blue tones. Understanding 470nm Photography A 470nm short-pass filter lets through light with wavelengths below 470nm—essentially violet (around 400nm) to blue (peaking at 470nm)—while blocking everything longer, like green (500nm+), red (600nm+), and infrared (700nm+).