two different pwered strobes

<p>I have a 500w and 1000w light. I set them up with the 1000w light as the key/ main, and the 500 as the fill light. I know that some people would set them up the other way around, but my question is more about setting the power output. I do not have a light meter either, but will most likely get one in the future. So if I set up the 1000w light as the main, and the 500w as the fill, do the respective power settings on each light correspond (1/4 power on each light has same output?), or is cutting the power of the 1000w light to half of the setting on the 500w light going to be considered balanced (1000w light at 1/4 power/ 500w light at 1/2 power)? I understand that distance from the subject etc and other variables can effect the light on the subject, as well as the kind of modifier used. I use a 36x48" Chimera softbox, and I have two umbrellas. Just curious.</p>

With all things being ideal and equal, the 1000w/sec unit set at 1/2 power should be equal in light output to the 500w/sec unit at

full power. You really need a flash meter.

<p>Shooting digital? Just use one light at a time, with the same modifier, set up in the same way. Point it at the same target (say, a piece of white or grey paper), and get the exposure basically under control (no clipping). Then look at the histogram for capture of the same target under the conditions you just escribed (1000w at 1/4 power, 500w at 1/2 power, etc). You'll quickly see if they're in the same neighborhood, or if the controls on the lights aren't as linear as you'd hope them to be. Either way, you'll know how to work with them in the absence of a flash meter.</p>

<p>Thanks Frank and Matt. I am shooting with a 5D, and the few times I have used the lights (I just got them) I figured that the power output would be as Frank suggested. I am assuming that it does not matter which light I use for the key, and which one I use for fill, but if what frank is saying is right, then I guess if i use the 1000w light for the key, and the 500w light for fill, then I can set the lights to the same power and get close to the 2:1 ratio. Is that right? <br>

Secondly, I keep hearing that you want the larger modifier on the fill side so the key focuses more on, say, an individual's face and torso etc, while the larger modifier fills in the shadow side more fully. Is that they way I should be thinking in terms of the modifiers I have?<br>

Finally, do you guys think it would be worth my while to get a slightly smaller softbox for the key, and use the 36x48 for fill? I am just thinking that it would be better to match the modifiers to get the same quality of light. If so, what are your views on Photoflex softboxes? Would a strip box be better for portrait work than a rectangluar/ square one? Thanks so much for your help so far. I really appreciate it.</p>

<p>"<em>I guess if i use the 1000w light for the key, and the 500w light for fill, then I can set the lights to the same power and get close to the 2:1 ratio. Is that right? "</em><br />If both lights are set at the same power level then you need to adjust the distance of the fill light to determine a 2:1 ratio.<br /><em></em><br>

<em>Secondly, I keep hearing that you want the larger modifier on the fill side so the key focuses more on, say, an individual's face and torso etc, while the larger modifier fills in the shadow side more fully"</em><br />The fill light should be as flat and non-directional as possible. if you have a large white wall you can bounce the light off that to create your fill. Usually a bigger fill light is better unless you are trying to create some type of effect.<br>

"<em>Finally, do you guys think it would be worth my while to get a slightly smaller softbox for the key, and use the 36x48 for fill</em>?"<br />It depends on what type of effect you are trying to achieve. It really doesn't matter, but usually a larger key light means softer light, meaning smoother transitions between highlights and shadows and a smaller key light means harder, more directional light.</p>

<p>Thanks for the answers to these question, Harry. You have set my mind straight on them. I have bought some lighting books, and read them all, but there is a lot to think about with respect to this aspect of photography. Take care.</p>

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<p>if i use the 1000w light for the key, and the 500w light for fill, then I can set the lights to the same power and get close to the 2:1 ratio. Is that right?</p>

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<p>If both lights are producing the same amount of output you'd vary one by distance to get your light ratio. But, 2:1 does not mean the main is twice the brightness of the fill. 3:1 lighting means the main is twice the fill and 3;1 is the ratio most commonly used for traditional portrait lighting.</p>

<p>The fill light produces X. If the main produces 2X then those areas of the subject's face illuminated by the fill alone get X light and those illuminated by main + fill get 2+1 = 3.</p>

<p>The benefit of using distance to help control the quantity of light illuminating the subject is that all else being equal, the closer the light-subject distance the larger the light source and the softer. A 60" umbrella set far enough from the subject with a light of sufficient power will be no softer than a point source of light.</p>

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<p>The fill light should be as flat and non-directional as possible. if you have a large white wall you can bounce the light off that to create your fill.</p>

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<p>+1. I often use a large white umbrella for my fill and a more directional soft box for my main light.</p>

<p>Henry Posner<br /><strong>B&H Photo-Video</strong></p>

<p>Thanks for the information, Henry. This is what I was thinking in terms of modifiers and their purpose. I appreciate all the help I can get! Take care.</p>