The Black Trees combo showed me something fundamental: there is magic not only in infrared and UV, but also in the visible spectrum.
By using filters that transmit very specific wavelengths, it becomes possible to create visual landscapes that have never been seen before.
A current example is the 430–512–631TB triple bandpass filter, which selectively transmits blue (430 nm), cyan/green (512 nm), and red (631 nm).
I tested it with various hot mirrors. These block infrared and/or ultraviolet light and are essentially the filters found in cameras before they are converted to full spectrum. There are many variations of them.
The most intriguing results came from combining the 430–512–631TB with the TSN575.
Here are the transmission curves of these two filters:
An interesting effect became clear when I photographed old fluorescent tubes in my studio, particularly in the stairwell. To the human eye, both tubes appear identical: a warm white.
With the 430–512–631TB + TSN575 combination, however, one tube turned pink, while the other glowed in a bluish cyan:
Why does this happen? Fluorescent tubes do not emit light as a continuous spectrum like sunlight or incandescent bulbs. Instead, they produce very narrow, specific emission lines, depending on gas composition, phosphor coating, and the tube’s age.
To our eyes, these lines blend into what we perceive as “warm white.”
The 430–512–631TB filter allows only three narrow spectral bands to reach the sensor. Combined with the TSN575, additional wavelengths are suppressed. What remains is not the perceived color of the lamp, but its spectral fingerprint.
Unfortunately, these classic tubes have almost disappeared from outdoor environments. Still, experimenting with different light sources has resulted in fascinating images.
Here are a few more impressions (shot with white balance around 5000K):
