[Alt-photo] uv content of led lights

Ryuji Suzuki rs at silvergrain.org
Sat Sep 23 21:19:33 UTC 2017

When you talk about LED lights, even if you limit it to 3000K or 2700K 
bulb shaped ones that come with Edison medium base, don't think they are 
all the same.

Most current LED bulbs use higher efficiency blue LED chips with 
fluorescent material that gives off longer wavelength lights, so that 
the whole output looks like white light. However, the materials vary, 
and so will be the power spectrum.

Some LED bulbs, especially ones that are labelled with high CRI values 
(color rendition index), may use LED chips that emit shorter wavelengths 
approaching UVA, combined with different fluorescent materials. These 
bulbs are more expensive and slightly less energy efficient, so people 
usually do not buy these without good reasons, but it's good to keep in 
mind these are less suitable for working with sensitizing materials.

If you run a test and detect some slight fog, then you could further 
reduce UVA or short wavelength blue light by bouncing the light off most 
non-shiny surfaces, or using Rosco UV gel filter.

Ryuji Suzuki
_A photograph is a secret about a secret. The more it tells you the less 
you know._ (Diane Arbus)

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