The gel filters appear dark gray in the middle image because the camera sets the exposure 1 60 f2 4 iso100 based on the visible light entering the lens.
Visible light cut off filter.
Ideally an uv cut filter should be completely transparent to the visible light and stop all the uv radiation with wavelengths shorter than 390 or 400 nm.
They re transparent in the bottom image because the exposure 1 30 f2 4 iso1000 is based on only the ir illumination which is pretty dim.
Short wave pass cutoff filter passes light from 325 450nm and blocks visible light from 500 700nm.
They are often used in devices with bright incandescent light bulbs such as slide and overhead projectors to prevent unwanted heating there are also filters which are used in solid state ccd or cmos video cameras to block ir.
Long wave pass trim filter lwp long pass filters block a select band of shorter wavelengths.
Cut off wavelength is indicated by λ cut off in figure 6.
5pcs 850nm nbp850 6 2 1 1mm ir infrared narrow bandpass filter visible light cut band pass glass.
Infrared cut off filters sometimes called ir filters or heat absorbing filters are designed to reflect or block mid infrared wavelengths while passing visible light.
2pcs infrared filter film visible cut off filter infrared light penetrates through film belt backing glue us 8 37 24 25 lot.
Cut off wavelength is a term used to denote the wavelength at which the transmission decreases to 50 throughput in a shortpass filter.
The measured filter here is a hoya hmc 52mm uv 0.
Mid infrared filters are often used as heat absorbing filters in devices with bright incandescent light bulbs such as slide and overhead projectors to prevent unwanted heating due to infrared radiation.
Raw measures of this filter between 350 nm and 2 500 nm are available here csv file 37 860 bytes.
Custom short wave pass filters are available on request.
Infrared cut off filters are designed to block or reflect infrared wavelengths but pass visible light.