Convert Foot-lamberts to Apostilbs
Convert Foot-lamberts (fL) to Apostilbs (asb) instantly and accurately.
Conversion Formula
asb = fL × 10.76391042
About Foot-lamberts
The foot-lambert (fL) equals 1/(π×0.09290304) cd/m² ≈ 3.426 cd/m², the luminance of a perfect diffuse surface emitting 1 lumen per square foot. The SMPTE standard for cinema screen luminance is 14 fL (≈48 cd/m²); home projectors are rated 10-35 fL. Still standard in US cinema and theatre engineering. 1 fL = 1/(π×ft²) cd/m².
About Apostilbs
The apostilb (asb) equals 1/π cd/m² ≈ 0.3183 cd/m², defined as the luminance of a perfectly diffuse Lambertian surface with an exitance of 1 lm/m². Introduced by the CIE in 1940 and used in European photometry standards and retinal illuminance calculations. 1 asb = 1/π cd/m² ≈ 0.3183 cd/m².
Quick Reference Table
| Foot-lamberts (fL) | Apostilbs (asb) |
|---|---|
| 1 fL | 10.7639 asb |
| 2 fL | 21.5278 asb |
| 5 fL | 53.8196 asb |
| 10 fL | 107.639 asb |
| 25 fL | 269.098 asb |
| 50 fL | 538.196 asb |
| 100 fL | 1076.39 asb |