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10/26/2006 11:34:49 AM · #1 |
I'm reading this book on lighting - can't tell you the name of it because I don't have it with me...
He states that you set the key light at a certain exposure - then the fill light at one stop down from that exposure, and the kicker light at one stop above that exposure for a 2:1:2 lighting ratio.
I totally understand all of that -
I have strobes in studio - here are my questions...
With just the meter in my camera - how can I determine what the kicker and fill exposures are?
Can I approximate these with distance ie. Have all the strobes firing at the same strength and put the fill twice as far away from the model, and the kicker half again as close?
Do I just need to pony up for a hand held light meter?
I guess I just need a way to roughly approximate the values I'm reading about and seeing in this book -
Any thoughts are greatly appreciated.
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10/26/2006 11:38:58 AM · #2 |
| well you'd have to take 3 different shots, and look at the histograms, or buy a light meter. |
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10/26/2006 02:40:31 PM · #3 |
that's helpful - any other ideas?
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10/26/2006 03:22:28 PM · #4 |
| I'd say to bite the bullet and get a flash meter. That said, you are correct that you could put the fill light twice as far from the subject as the key and kicker for 2:1:2(assuming all three strobes are the same power output). Then you would take a shot and check the histogram for overall exposure. If the ratio looks right, adjust the aperture if necessary. |
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10/26/2006 05:49:32 PM · #5 |
thanks for your input Jemison! Any other ideas I should consider?
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10/26/2006 05:54:16 PM · #6 |
Lightmeter is the best solution.
or keeping the lights at same distance and powering them up/down
I don't think that moveing the lights away reduces the strength linearly, so keeping the lights at twice distance will not reduce the strength to half. If it was a point source, the light will reduce by square law, but this is not a point source and the reflector on your lights will try to straighten them, and the diffuser will diffuse it.. so you don't really know what law if follows :) Assuming a linear scale is wrong and won't give you desired results. |
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10/26/2006 06:36:56 PM · #7 |
Originally posted by gaurawa:
Lightmeter is the best solution.
or keeping the lights at same distance and powering them up/down
I don't think that moveing the lights away reduces the strength linearly, so keeping the lights at twice distance will not reduce the strength to half. If it was a point source, the light will reduce by square law, but this is not a point source and the reflector on your lights will try to straighten them, and the diffuser will diffuse it.. so you don't really know what law if follows :) Assuming a linear scale is wrong and won't give you desired results. |
Yes, doubling the distance of a light source from the subject decreases the intensity to *1/4th* the original (not 1/2...my bad). However, it doesn't matter whether you have a point source or reflected...it follows the same inverse square law. Of course mixing types of lights makes things more complicated, but OP asked about ratios without mentioning light qualities, and I stated my assumption that they were all of equal output (reflectors, etc. will modify the effective output). Also, I don't see that adjusting output is any more effective than adjusting distance as far as lighting ratios goes. It may be easier and better for reasons other than light ratio, such as "softness" of light sources (closer is softer, all else equal)
At any rate - a lightmeter is the right way to go. |
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10/26/2006 08:42:51 PM · #8 |
I like the distance idea *except* that you need to remember how distance affects the quality of light. The further away the light gets, the harsher the light source becomes. (think how big the sun is, and yet it becomes a "point source of light" due to the distance)
My point being, that pulling a nice softbox 10 feet away from the subject just to get the right amount of light, might be a waste of a good softbox.
You could always use a gray card to get the varying light levels. I prefer a light meter combined with "experimentation" (sometimes an exact ratio isn't what you really want anyway)
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10/26/2006 08:50:47 PM · #9 |
Originally posted by digitalknight:
With just the meter in my camera - how can I determine what the kicker and fill exposures are? |
Trial and error. It's one of those things that you can do, but it's gonna be a PITA every time.
Originally posted by digitalknight:
Can I approximate these with distance ie. Have all the strobes firing at the same strength and put the fill twice as far away from the model, and the kicker half again as close? |
Yes, but as soemone pointed out earlier, the distance also affects the quality of the light too, specifically, the diffusion.
Originally posted by digitalknight:
Do I just need to pony up for a hand held light meter? |
You don't have to, you can prolly get by in most cases with the trial and error method, but if you are at all serious about studio work, you really should get a flashmeter.
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10/26/2006 08:53:40 PM · #10 |
Well, if the strobes can be adjusted in stops, just use your spot meter for the fill light. Set the key and fill one stop higher and
you're goot to go. But what do I know. The guy at this site thinks flash meters are obsolete:
//strobist.blogspot.com/
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10/26/2006 09:02:17 PM · #11 |
Originally posted by dwterry:
My point being, that pulling a nice softbox 10 feet away from the subject just to get the right amount of light, might be a waste of a good softbox. |
That point made me realize why I need a bigger softbox. To get the light soft you need it decently close, as you said, but if you want shallow DOF, sometimes the strobe powered all the way down at ISO200 is still f/7 or smaller. If I could have a lager diffusion scrim or softbox set farther back and the lights dialed in right, that would change the whole thing and I could maybe get some good shallow DOF with the strobes. Sweet!
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10/26/2006 10:17:00 PM · #12 |
thanks for the great comments - this will give me a lot to experiment with
My thought was if I did it 'by the book" the first time - then I would have a "feel" for where and how bright etc the lights were, and I could start working off of that.
At all ratios 4:1:2 etc.
Kind of how I learned the computer - read just enough to be dangerous, and have been winging it ever since.
Thanks again all!
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10/26/2006 11:08:59 PM · #13 |
By all means get a meter.
If you're gonna stick with this, then get a sekonic L358 (or it's big brother, but you don't need that much meter)
great full function meter for ambient and flash. the reason i suggest this meter is you can get a pocket wizard radio trigger module for it. cause one day you're gonna get real tired of being tied to your lights, and then have to plug the lights into the meter to trip the lights to measure them...you'll want pocket wizards (by far the #1 radio system in popularity) and the module lets you trigger the PW receivers without wires - awesome the first few times you do it and then it's just convenient as all hell.
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10/26/2006 11:15:06 PM · #14 |
I did my lighting "by eye" for a couple of years, and did pretty flippin well, but did have some bad shoots due to trial & error. Then, just because I didn't have one, I bought a light meter. It changed my world. I meter my studio before a client comes in, with the light set up I think I need to use and bam... we're on. Never a blown highlight, never a lost shadow. Granted I still experiment A LOT with my lights and don't always stop & re-meter, but now I have a pretty good feel for where the lights actually should be and how the camera should be set for the best exposure. It's helped my photography so much - best $150ish I've spent yet. Mine is Polaris
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