Watts and lux measure different things
Watts relate to the fixture’s electrical power. Lux is the illuminance falling on a surface at a given distance. A higher wattage does not mean a light will be brighter or more useful on every shoot; optical design, beam angle and efficiency also decide the result.
Two lights in the same 800 W class show this well: the Nanlite Forza 720 gives 10,200 lux at 3 m, 5,600 K with a reflector, while the bi-colour Forza 720B gives 7,919 lux under the same conditions. Same power, different light engine.
Measuring conditions are part of the data
The distance, colour temperature and accessory written next to a lux figure are not footnotes. Comparing two figures without matching conditions is misleading. Measurements of the same light with different accessories make this clear:
| FS-300C, 5,600 K | 1 m | 3 m |
|---|---|---|
| Bare light | 18,050 lux | 2,097 lux |
| With reflector | 48,850 lux | 4,907 lux |
| FL-20G Fresnel lens, spot | 147,000 lux | 11,690 lux |
| FL-20G Fresnel lens, flood | 38,960 lux | 4,627 lux |
Change the accessory, change the result
Just by changing the accessory, the same light shows anything from 18,050 to 147,000 lux at 1 m. That is why comparing one product’s highest lux figure with another product’s bare measurement gives the wrong answer.
If you will use a softbox or diffusion, do not read the bare figure as the final result. A softbox softens the light and lowers illuminance; Fresnel lenses and projection attachments narrow the beam and concentrate it. If there is no measurement for your setup, mark the value as unknown.
Distance drops the numbers fast
As a light moves away, illuminance falls roughly with the square of the distance. In the FS-300C’s reflector measurement, 48,850 lux at 1 m drops to 4,907 lux at 3 m: tripling the distance cuts illuminance to about a tenth. Compare products on the row closest to your own working distance.
Read colour modes separately
On full-colour lights, white-light figures do not carry over to colour modes. For example, the FC-500C gives 77,110 lux in 5,600 K white, 34,630 lux in green and 6,750 lux in blue at 1 m with a reflector. If you are planning coloured backdrops or effects, check the row for that colour.
Don’t forget coverage
A light concentrated on a small area and one spread over a wide surface answer different needs. A high reading at the centre does not mean the same illuminance across the whole frame. For wide desks, green screen backdrops or moving presenters, ask about beam angle and coverage too.
A comparison table template
Use the same headings for every model on your shortlist, so missing information becomes visible and marketing copy cannot stand in for a technical comparison. For model-level examples, see our FS-300C vs FC-500C and Forza 720 vs 720B guides.
- Measuring distance and colour temperature
- The exact reflector, lens or other accessory
- The area the light has to cover
- Planned softbox or diffusion
- Fan noise and control options
- Missing information to confirm with the manufacturer
Frequently asked questions
Does higher wattage always mean better light?
No. Electrical power alone does not describe the result on camera; it has to be weighed with optics, working distance, light distribution, colour mode and accessories.
What is the difference between lux and lumens?
Lumens describe the total light leaving the source; lux describes the illuminance on a surface. For film and video lights, manufacturers usually publish lux measured at a set distance with a set accessory, which is more useful for predicting the result on set.
