Light Loss and Mired shift values for Gels and Diffusion

Surprisingly, you've really got to dig online to find basic cinematography information like stop values and Mired shifts for Gels. The Lee Filters website has these figures but trawling through their catalogue to find them is slow going so I thought I'd post it all here. While this is maybe not so useful when scrambling around on set, I like to refer to this info when designing lighting plots or trying to put together an equipment or expendables order.

LIGHT LOSS FOR COMMON DIFFUSION TYPES:

White Diffusion "216": 1 1/2 stops

1/2 White Diffusion "250": 3/4 stop

1/4 White Diffusion "251": 1/3 stop

1/8 White Diffusion "252": 1/4 stop

Opal "410": 1/2 stop

Light Opal Frost "420": 1/4 stop

Hampshire Frost "253": 1/4 stop

Heavy Frost "129": 2 stops

Grid Cloth "430" or Silent Grid Cloth: 2 1/2 stops

Light Grid Cloth "432" or Silent Light Grid: 2 stops

1/4 Grid Cloth "434" or Silent 1/4 Grid: 1 stop

Full Tough Spun "214": 2 1/2 stops

1/2 Tough Spun "215": 1 1/2 stops

1/4 Tough Spun "229": 3/4 stop

Artificial Silk: 1 2/3 stops

1/4 Silk: 2/3 stop

China Silk: 1 stop

Unbleached Muslin: 2 stops

Bleached Muslin: 2 stops

Heavy Diffusion:

Muslin, Grid Cloth, 216, Heavy Frost

Medium Diffusion:

Silk, Spun, 250, Light Grid

Light Diffusion:

Opal, Hampshire Frost, 251, 252

LIGHT LOSS FOR COLOR CORRECTION GEL:

CTB (Color Temperature Blue) "201": 1 2/3 stops

1/2 CTB "202": 1 stop

1/4 CTB "203": 2/3 stop

1/8 CTB "218": 1/3 stop

CTO (Color Temperature Orange) "204": 1 stop

1/2 CTO "205": 2/3 stop

1/4 CTO "206": 1/3 stop

1/8 CTO "223": 1/3 stop

CTS (Color Temperature Straw) "441": 1 stop

1/2 CTS "442": 2/3 stop

1/4 CTS "443": 1/3 stop

1/8 CTS "444": 1/3 stop

Plusgreen: 1/2 stop

1/2 Plusgreen: 1/4 stop

1/4 Plusgreen: 1/8 stop

1/8 Plusgreen: 1/8 stop

Minusgreen: 1 stop

1/2 Minusgreen: 1/2 stop

1/4 Minusgreen: 1/4 stop

1/8 Minusgreen: 1/4 stop

MIRED SHIFTS FOR COLOR CORRECTION GEL:

MIRED's are used for calculating color temperature conversions. The math always gets lost in my head so I often use Lee's online MIRED calculator >>>

Here's a link to Rosco's Filter Facts PDF that has a good explanation of the Mired Formula and how to use it >>>

TO INCREASE KELVIN:

CTB (Color Temperature Blue)-131 MIRED (Converts 3200k to 5500k or 2900k to 5200k)

1/2 CTB -68 MIRED (Converts 3200k to 4100k or 2900k to 3800k)

1/4 CTB -30 MIRED (Converts 3200k to 3500k or 2900k to 3200k)

1/8 CTB -12 MIRED (Converts 3200k to 3300k or 2900k to 3000k)

TO DECREASE KELVIN:

CTO (Color Temperature Orange) +167 MIRED (Converts 6500k to 3200k or 5500k to 2900k)

1/2 CTO +81 MIRED (Converts 5500k to 3800k)

1/4 CTO +42 MIRED (Converts 5500k to 4500k)

1/8 CTO +20 MIRED (Converts 5500k to 4900k)

CTS (Color Temperature Straw) +160 MIRED (Converts 5500k to 3200k)

1/2 CTS +81 MIRED (Converts 5500k to 3800k)

1/4 CTS +42 MIRED (Converts 5500k to 4500k)

1/8 CTS +20 MIRED (Converts 5500k to 4900k)