Apostilb (asb)
1/π candela per square meter. Used in perimetry (visual field testing).
What is an apostilb?
- Symbol
- asb
- Quantity
- Luminance
- Unit system
- other
- Definition
- 1/π candela per square meter. Used in perimetry (visual field testing).
- Exact
- Yes, the value is exact by definition
- Source
- NIST Special Publication 811 (2008), Appendix B.8
Common applications
Used in eye care for visual field testing (perimetry), where stimulus brightness is often given in apostilbs or decibels.
Apostilb in other luminance units
- 1 asb ≈ 0.3183098862 cd/m²Candela per square meter (nit)
- 1 asb ≈ 0.0003183098862 kcd/m²Kilocandela per square meter
- 1 asb ≈ 0.00003183098862 sbStilb
- 1 asb ≈ 0.02957195609 cd/ft²Candela per square foot
- 1 asb ≈ 0.0002053608062 cd/in²Candela per square inch
- 1 asb = 0.09290304 fLFoot-lambert
- 1 asb = 0.0001 LaLambert
Apostilb quick reference
| Apostilb | Candela per square meter (nit) | Foot-lambert | Kilocandela per square meter |
|---|---|---|---|
| 1 asb | ≈ 0.3183098862 cd/m² | = 0.09290304 fL | ≈ 0.0003183098862 kcd/m² |
| 10 asb | ≈ 3.183098862 cd/m² | = 0.9290304 fL | ≈ 0.003183098862 kcd/m² |
| 100 asb | ≈ 31.83098862 cd/m² | = 9.290304 fL | ≈ 0.03183098862 kcd/m² |
| 1000 asb | ≈ 318.3098862 cd/m² | = 92.90304 fL | ≈ 0.3183098862 kcd/m² |
Where the apostilb fits
The next larger luminance unit is the candela per square meter (cd/m²). 1 asb ≈ 0.3183098862 cd/m², and 1 cd/m² ≈ 3.141592654 asb.
Frequently asked questions
- How many candelas per square meter are in one apostilb?
- One apostilb ≈ 0.3183098862 cd/m² (candelas per square meter).
- How many foot-lamberts are in one apostilb?
- One apostilb = 0.09290304 fL (foot-lamberts).
- How many kilocandelas per square meter are in one apostilb?
- One apostilb ≈ 0.0003183098862 kcd/m² (kilocandelas per square meter).