Light Value (LV) is like the exposure value, but it also includes a third element, the speed of the film. Because it includes all camera-related properties and settings, the LV is an absolute measurement of the amount of light, as a camera-independent light meter would read. At ISO 100, it is identical to the exposure value. At ISO 200, the Light Value associated with a certain aperture and shutter combination will be one less than the exposure value; at ISO 50, it will be one more, etc.
The tables below relate aperture and shutter speed to Exposure Values, or to Light Values with ISO 100 film.
| f/1.0 | f/1.4 | f/2.0 | f/2.8 | f/4.0 | f/5.6 | f/8.0 | f/11 | f/16 | f/22 | f/32 | f/45 | f/64 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 128s | -7 | -6 | -5 | -4 | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 |
| 64s | -6 | -5 | -4 | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
| 32s | -5 | -4 | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| 16s | -4 | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| 8s | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| 4s | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| 2s | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
| 1s | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| 1/2s | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |
| 1/4s | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| 1/8s | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| 1/15s | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
| 1/30s | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 |
| 1/60s | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 1/125s | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 |
| 1/250s | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 |
| 1/500s | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 |
| 1/1000s | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 |
| 1/2000s | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 |
| 1/4000s | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 |
| 1/8000s | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 |
| LV | Description |
|---|---|
| 15 | Direct sun |
| 10,11 | Indirect sun - sky-light on a clear day |
| 8 | Interior daytime, indirect lighting, room has sunbeams in it |
| 7 | Interior daytime, room with skylights and no direct sun entering |
| 6 | Interior daytime, room with windows and no direct sun entering |
| 5 | Interior night, bright room with hundreds of watts of incandescent lighting or fluorescent equivalent |
| 4 | Interior night, average illumination |
| 3 | Exterior night, directly under sodium vapor street light |
The next table gives the reflectances of some common subjects, as a deviation from that of the grey card. You'd combine this information with the ambient light information from the table above to calculate the amount of light coming from a particular object:
| Stops | Description |
|---|---|
| +5 | |
| +4.5 | |
| +4 | |
| +3.5 | |
| +3 | |
| +2.5 | Generic white fabric/paper |
| +2 | |
| +1.5 | Caucasian skin |
| +1 | |
| +0.5 | |
| 0 | Grey card |
| -0.5 | |
| -1 | Brick, tree bark, dark green vegetation |
| -1.5 | |
| -2 | |
| -2.5 | Black fabric, faded (such as worn denim) |
| -3 | Black fabric, dark |
| -3.5 | |
| -4 | Black velvet |
| -4.5 | |
| -5 |
The following table of self-luminous subjects gives the brightness of the subject in units of LV. This table includes situations where the ambient light and reflectance of the subject cannot be measured independently.
| LV | Description |
|---|---|
| 15 | Hazy sky |
| 12.5 | Clear, dark sky |
| 11 | Dark overcast/stormy sky |
| 9 | Neon signage |
| 2 | Realistic night exposure for distant skyline |
These tables are updated as I measure and record more things.
The polarizer information has finally gotten its own page.
Copyright (C) 2006 by
Terran Melconian.
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