ISO100 | ISO200 | ISO400 | ISO800 | ISO1600 | ISO3200 |
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1 | 1.4 | 2 | 2.8 | 4 | 5.7 |
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Photography distance range = Guide number × ISO speed coefficient ÷ Aperture
Ex) 35
F4, ISO: 400
25 (Guide number) × 2 (ISO speed coefficient) ÷ 4 (Aperture) = 12 m The flash light reaches to 12 m.
When using the HSS flat flash (flash with HSS)The flash range becomes shorter than that of normal flash photography when the high speed sync is used. You can get the correct flash range using the following guide number table and an ISO speed coefficient.
Guide number
35
Shutter speed |
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| 16* | 24 | 28 | 35 | 50 | 70 | 105 |
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1/250 | 4.7 | 8.8 | 9.1 | 9.5 | 10.9 | 13.4 | 16.4 |
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1/500 | 3.3 | 6.2 | 6.4 | 6.7 | 7.7 | 9.5 | 11.6 |
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1/1000 | 2.4 | 4.4 | 4.5 | 4.7 | 5.5 | 6.7 | 8.2 |
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1/2000 | 1.7 | 3.1 | 3.2 | 3.4 | 3.9 | 4.7 | 5.8 |
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1/4000 | 1.2 | 2.2 | 2.3 | 2.4 | 2.7 | 3.4 | 4.1 |
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1/8000 | 0.8 | 1.6 | 1.6 | 1.7 | 1.9 | 2.4 | 2.9 |
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1/12000 | 0.6 | 1.1 | 1.1 | 1.2 | 1.4 | 1.7 | 2.1 |
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* When the wide panel is attached.
GB50