Is a Bowens Gemini 200 powerful enough for studio shooting at 3–5m, or should I get the 400?
Asked 6/9/2013
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I'm choosing an entry-level studio lighting kit and am considering the Bowens Gemini 200 or Gemini 400. I typically shoot in a studio with the camera about 3–5 meters from the subject. Would a pair of Gemini 200 monolights be enough, or is it better to go for the 400s? I'm mainly trying to understand whether the 200 has enough power at those working distances, especially if I use modifiers like umbrellas or softboxes.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
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The guide number of the Gemini 200 is 54m at ISO 100 for full power, so at f/8, you would need the strobe to be 6.75 meters away. The formula for this is:
GN = distance x f-number
So, from that you can work out your distances for the lights. Bear in mind that modifiers, such as umbrellas or softboxes, will reduce the light by some amount. You'll have to check the documentation that comes with them in order to be sure of the amount as there is no rule of thumb for that. However, lets say though, that it costs you a stop to have a bounce umbrella and you still want to shoot f/8. Then the a full stop lost from f/8 is f/11 (in other words, shooting with the umbrella is like stopping down to f/11 in light loss) and you would have formula:
distance = 54/11 = 4.9m
At any rate, I suspect you're fine with Gemini 200 as I'd be surprised if you got them up to full power in a close studio setting. You'll probably also do what I did eventually and buy yourself an incident light meter to get more accurate measurements.
Originally by user472. Source · Licensed CC BY-SA 4.0
user472
13y ago
0
Generated from our catalog & community — verify before relying on it.
A Gemini 200 is likely adequate for many studio setups at 3–5m, depending on your aperture and modifiers. One answer cites a guide number of 54m at ISO 100. Using GN = distance × f-number, that means at full power you could theoretically get about f/8 at 6.75m with the bare light.
Modifiers reduce output. If an umbrella or softbox costs about 1 stop, the effective f-number for the calculation becomes roughly f/11, giving about 54/11 = 4.9m for an f/8 exposure. So at 3–5m, a Gemini 200 should still be workable for many situations, especially if you’re not heavily diffusing the light.
The main reason to choose the 400 would be extra headroom: more power for larger modifiers, smaller apertures, lower ISO, or subjects farther from the lights. But based on the provided numbers, the 200 should be sufficient for typical studio portrait distances.
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