Roland W Offline Upload & Sell: On
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Lets get the numbers a little closer to typical. Typical strobe maximum power is 1200 Watt Seconds. Typical modeling light is 400 Watts. Sync speed for full frame camera is usually 1/250th of a second. Typical energy transfer of a 1200 Watt Second strobe into a 1/250th exposure gives an effective power of about 600 Watt Seconds.
The 400 Watt modeling light is thus about equal to a 1.60 Watt Second strobe (400 Watts times 1/250th of a second equals 1.6). So the modeling light is 1/375th of the power of the strobe, which is about 8.5 stops different. That is a big difference. An alternate view is that you would need a modeling light of about 75,000 Watts to get the same exposure that you can get from the strobe at 1/250th of a second. Try modeling in front of a 75,000 Watt light from about 8 feet away and see how long you last.
If you go through the measurements from a real strobe with a light meter, you get results fairly similar to the above theoretical numbers.
With my 600 Watt Second portable strobe, and with a some what lossy modifier mounted on it, I can overpower the full mid day sun at a lighting distance that has me covering a model standing, and working at 1/250th of a second exposure. The sun becomes my background light and often my hair light, and my strobe is my main light, and then another strobe or even a portable flash is my fill light. It is a whole new world of where and what and when you can shoot when you can overpower the sun.
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