So, I have created (by being cheap) somewhat of a hybrid lighting setup. I have a white background I am lighting with 2000W (equivalent) cheapo softboxes. They have 5 daylight CFL's each and cheapo stands. They light the backdrop evenly and are adjustable (each bulb has a switch).
And they might not even be showing up in the picture, or contributing as much as you want.
They're 2000W "equivalent" to household tungsten. That means they're probably a grand total of 500W of fluorescent. I'm betting five 55W bulbs each.
Speedlights don't have an "equivalent", they work by the same technology as the CFL, ionized gas. So, that 500W number for your CFL banks is important.
The thing that throws most people when they start playing with continuous lights, and throws them even harder when they start mixing continuous lights and strobes, is the difference between "power" and "energy". Imagine you have a bucket containing a gallon of water. That's "energy", the amount of "stuff" that you actually have. Energy is measured in Joules, or watt-seconds. Energy is what matters, just like the amount of water you have is what matters. If you need to make a cup of tea, you need to have 8 ounces of water. It doesn't matter if you dipped it out of the bucket in one scoop, or you filled the cup with an eye dropper, one drop at a time, as long as you get 8 ounces, you can make tea.
Pictures are the same way. A particular picture, ISO, aperture, and distance, may need a certain number of watt-seconds. A speedlight can deliver about 60 watt-seconds. If your picture needs 30 watt-seconds, you get a good exposure with the speedliight on half "power". I put power in quotes, because it's not "power" at all, that's the "half energy" setting. The speedlight controls work on energy, not power. This is good, because (repeat this a couple of times) "energy makes pictures".
The continuous lights produce "power", in watts. Power is the flow of energy. You have 500W of power. If you let it flow for 1/10 second, you have 500W * 1/10 second or 50 watt-seconds of energy, pretty close to the energy of a speedlight.
My intention was to use continuous as a main light, but I don't like it (blinding to the models, bulky, and just not the look I am after). So, I am now experimenting with a speedlite as a main, with the continuous backlighting. I use the boom as a hairlight to keep it out of the models face. I am starting to refine the results, but haven’t found anyone online who uses a setup like this. Is there a reason for this?
Yes. It's a flaming pain. You saw that video and site that Chuck Dembrey linked. That guy was shooting at 1/15 sec, because he needed to let his 5000W of lights "flow" that long to get enough energy to balance his studio strobes. That's about 400 watt-seconds. Pros work with a lot of energy on fashion shoots. I have four 640 watt-second strobes, one 1300 watt-second, and maybe eight 300 w-s that I use for smaller stuff. A typical 4 light setup lets me hit a subject with up to 3200 w-s, and typical shots are lower, but still up around 600. That's the energy of 10 speedlights.
I know I can't power match, and the adjustments are a little crude, but am I missing something?? Is there a reason why most people are all flash, or all continuous??
OK, first off, more people aren't "all flash, or all continuous", most people are "all flash". All continuous is rare, because you just can't get enough energy, without insane power. Your models complained about 500W. You have to let 500W flow for 1/10 second to get 50 w-s, the energy of a single speedlight. It's hard to take a sharp shot of a "normal" person (jittery senior, nervous bride) at 1/10 sec. because people have little body motions all the time. You normally shoot people at 1/30 sec or faster. That insures you'll have a good percentage of "keepers". 1/30 sec * 500 W = 16 w-s, 1/3 of a speedlight. Look at the strobist site, 4-8 speedlights per picture, little home-made brackets to use 2 or 4 speedlights together as a "main".
Now, one reason why people don't mix in continuous for background is that it's hard to make everything "track". You're having trouble with your lighting ratios, because you don't understand power vs. energy. Few do.
Yes, if you're all flash, everything "tracks" when you adjust energy. Is your background 1/2 too hot? Drop the setting on that strobe half a stop. Done. It's that simple.
If mix continuous and strobe, then you've got a problem. Is the background 1/2 a stop too hot? You can either reduce the continuous "flow" by bumping the shutter speed 1/2 stop faster, or increase the main flash energy 1/2 stop, then stop the aperture down 1/2 stop to compensate. A switch that lets you select 1 through five bulbs is just a 2.3 stop range, and you often can't use that little range, because you're reducing the power of something that didn't have enough in the first place. The speedlights adjust over an 8 stop range, and so do good studio strobes.
You've got a second problem, if you're shooting down where motion is a prolem, 1/30 sec or slower, you get motion blur "silhouettes" of background behind the subject. Again, that worked for the fashion shoot in the video, because they planned for it, but it's not an effect you want in every shot.
We won't even get into the whole CRI and color temperature issues...
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Rahon Klavanian 1912-2008.
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