Opinion: Lumens should be an SI base unit
Disclaimer: I’m only an armchair metrologist. Experts, have mercy
In learning the definition of a candela (watts per steradian of visible light), I realized that lumens are simpler and easier to understand despite being a derived unit. They’re also widely used in the real world, unlike candela.
The original definition of a candela is the luminous intensity of a whale fat candle. If the entire point of a candle is to radiate in every direction, shouldn’t the base unit measure the total flux (light) the candle produces? Using lumen as a base unit is also simpler because its definition would equal the power of a light source weighted for human vision, and there’s no need to understand solid angle unless you need to use the (very niche) candela.
 “3 led circuit” by spatulated is licensed with CC BY 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/2.0/
 “High Power Green Laser, Dark Background (1)” by FastLizard4 is licensed with CC BY-SA 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-sa/2.0/
 Andy Anderson, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
Last modified: 09/03/2021