Hi guys
Seems there might be a problem getting the real definitions and meanings of the photometric quantities and parameters on the subject of light...
Let us start from here:
The study of light, its generation, propagation/transmission, manipulation, utilisation, properties and behaviour is known as
Optics. This is one of the science subject studied in great detail in physics.
Photometry is the actual measurement of visible light in terms of its perceived nature/ brightness to human eye and vision....
The commonest photometric quantities relevant to the various photometric computations and designs are:
Photometric quantity.............
SI Unit............
Unit Symbol1. Luminous Energy......Lumen Second.......lm-s
2. luminous Flux.......Lumen (cd-sr)......lm
3. Luminous Intensity...Candela (lm/sr)....cd
4. Luminance...........Candela/m2........cd/m2
5. Illuminance.........Lux (lm/m2)........lx
6. Luminous Emittance..Lux (lm/m2)........lx
7. Luminous Exposure...Lux-Second........lx-s
8. Luminous Energy density...Lumen Sec/m3...lm-s/m3
9. Luminous Efficacy...Lumen/Watt........lm/W
I bet upto here it is so far so good...
...besides, the presence of a safe alone does not signify that there is money inside...