Visible LED lamps have an infrared component other than visible light. This infrared light gives a noise in the infrared fluorescence photography. White LED lamp emits Infrared roughly between 700 and 800. See Wikipedia; white LEDs are Phosphor-based LEDs and have an emission curve with a tail in the very close IR, see here.
So, for a perfect IR Fluorescence photography we still need to have a sole visible light source. We can still use a LED lamp but we need to filter it with our X-Nite CC1 filter that allows VIS and cuts the closest IR. This is the image of the little experiment setup. I use a Cree LED 3000K 550 LUMEN. I’m taking the following images with the UV-VIS-IR modified Nikon D800.
Let’s now screw on the Nikon camera an IR filter (Visible cut off). The Infrared component of the LED lamp it’s noticeable through the filter.
Cree LED 3000K 550 LUMEN as seen by the UV-VIS-IR modified Nikon D800 with an IR filter screwed on camera.A perfect – and cheap – only VISIBLE source of light can be made just screwing on the LED lamp the X-Nite CC1 filter. Indeed, this filter cuts off even the closest IR and allows just the VIS light. See the image below, any IR is cut off!. This is a perfect Visible-only light emitter.
Cree LED 3000K 550 LUMEN as seen by the UV-VIS-IR modified Nikon D800 with an IR filter screwed on camera and the X-Nite CC1 filter screwed on the LED lamp.As usual, a video, to recap what just said.
Thank you for sharing this. I wonder what your exposure time of the last image is; camera with IR pass filter and LED covered with UV/IR cut filter. Inspired by you I set up almost the same (LED 4000K and 400 lumen, BG40 VIS pass, Travor 850nm IR pass) and noticed transmission of IR on my images made of this “VIS only” light. The X-Nite CC1 data show at 850 nm a transmission of at least 1%. Is the image of your leaf indeed IR fluorescence or an underexposed IR image of that tiny bit of IR passing the X-Nite CC1? Any help welcome.
Hi Herman,
You should use a filter cutting over 950 nm. For those images I used such a filter so that the near infrared leaking from the X-Nite is not an issue for this IRF imaging method