Color Temperature & White Balance vs. T-Stop
Comparing 2 standards across 12 specifications. 12 key differences identified.
Color Temperature (measured in Kelvin / K, standardized under CIE illuminant standards) defines the spectral chromaticity of light emitted by an idealized black-body radiator. Governing camera white balance, it ranges from warm Candlelight (1800K) and Tungsten Studio (3200K) through Photographic Daylight (5600K / CIE D55) to Overcast Sky (6500K / CIE D65) and Deep Blue Shade (8000K–10000K).
The T-Stop (Transmission Stop, standardized under ISO 517 for cinematography) is a photometric measurement of a lens's true light transmission (T = f / √Transmittance), correcting the theoretical geometric f-stop for physical light lost to glass reflection and optical element absorption. Standardized across all cine primes (Cooke, ARRI, Zeiss, Angénieux).
Specification Comparison Table
12 Parameters| Parameter / Spec | ||
|---|---|---|
|
Tungsten / Halogen Standard
|
3200 K (Standard interior film incandescent / studio tungsten quartz lighting) | — |
|
Commercial Warm White Home Lighting
|
2700 K to 3000 K (Warm ambient household LEDs and Edison bulbs) | — |
|
Direct Sunlight / Flash Standard
|
5500 K to 5600 K (Standard photographic electronic flash and noon direct sunlight) | — |
|
CIE Standard Illuminant D65
|
6504 K (Standard average daylight definition, sRGB / Rec.709 / Display P3 monitor white point) | — |
|
Overcast Sky & Open Shade
|
6500 K to 8000 K (Cool blue-tinted indirect atmospheric skylight) | — |
|
Mired Shift Calculation
|
Mired = 1,000,000 / Kelvin (Used for precise optical color temperature warming/cooling filters) | — |
|
Tint Tint Scale (Green / Magenta)
|
Orthogonal CC tint axis (corrects for fluorescent mercury gas spikes and green LED CRI spikes) | — |
|
Mathematical Formula
|
— | T-Number = F-Number / √(Transmittance Percentage as a decimal) |
|
Physical Meaning
|
— | A lens set to T2.8 transmits the exact same photometric illumination to the sensor as an ideal 100% transparent lens at f/2.8 |
|
Complex Zoom Glass Loss
|
— | A 18-element zoom marked f/2.8 with 80% transmission has an actual transmission rating of T3.1 (0.3 stops darker than f/2.8) |
|
Cinema Iris Ring Markings
|
— | Marked strictly in T-stops with linear mechanical spacing and clickless 0.8 MOD gears for follow focus rigs |
|
Shot-to-Shot Matching
|
— | Switching from a 24mm wide lens to a 85mm telephoto on a movie set, both set to T2.8, is designed to hold exposure and luminance effectively constant across the cut |