| Illumination Required (in Footcandles) for Correct Exposure at 1/50 Second | |||||||||
| Exposure Index | T1.4 | T2 | T2.8 | T4 | T5.6 | T8 | T11 | T16 | |
| 25 | 100 | 200 | 400 | 800 | 1600 | 3200 | 6400 | 12800 | |
| 40 | 62.5 | 125 | 250 | 500 | 1000 | 2000 | 4000 | 8000 | |
| 64 | 40 | 80 | 160 | 320 | 640 | 1280 | 2560 | 5120 | |
| 100 | 25 | 50 | 100 | 200 | 400 | 800 | 1600 | 3200 | |
| 125 | 20 | 40 | 80 | 160 | 320 | 640 | 1280 | 2560 | |
| 160 | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | |
| 200 | 12.5 | 25 | 50 | 100 | 200 | 400 | 800 | 1600 | |
| 250 | 10 | 20 | 40 | 80 | 160 | 320 | 640 | 1280 | |
| 320 | 8 | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | |
| 400 | 6.25 | 12.5 | 25 | 50 | 100 | 200 | 400 | 800 | |
| 500 | 5 | 10 | 20 | 40 | 80 | 160 | 320 | 640 | |
| NOTE: Film Tests Should be Used to Verify Results | |||||||||