Photographer
Ron Blouch
Posts: 34
Harrisburg, Pennsylvania, US
Hi,
After reading many, many questions, answers and what not I am interested in why photographers almost always describe their lighting set ups as I set my power light at half power or quarter power or 500 watts. What does this mean?
I feel if you want to describe your lighting speak in f stops. As an example: I set the key light at f8 and the fill at 5.6. Now I know how you actually lighted the subject.
When I hear the power numbers 1000w,500w etc. it really does not tell me anything. At 1000w how close is the key light? 5 feet, 10 feet from the subject. If you move the key light away or closer to the subject the power will change accordingly. So telling me how much power you are using does tell me much of anything.
Just thought I would throw this out. Maybe my thinking is all wrong.
Photographer
Simon Gerzina
Posts: 2288
Brooklyn, New York, US
I think that part of the problem is that a lot of digital photographers, especially less-experienced ones, don't shoot with light meters...so they don't know what each light meters at, they only know what the turned the knob on their monolights to. Further, I think many of them have only experienced their own lighting gear, so they don't understand that "half-power" on a 320ws Alien Bee unit is totally different than "half-power" on a 2400ws Profoto pack that's driving 3 heads asymmetrically with a second pack driving another 2 heads. Or, like you pointed out, "half-power" means something different when your light is 10' away from a model vs. 10" away.
Photographer
Lens N Light
Posts: 16341
Bradford, Vermont, US
Well, it really doesn't matter what F-stop your lights are at. What counts is the ratio of the key to fill to hair to background.
The only thing you are controlling by the actual power is the aperture and thus, of course the DOF. Since so many other factors also affect the DOF, that dimminishes in importance as a factor of flash power.
Knowing that as you decrease the power output of your strobes, you also decrease the recycle time can be important, depending on your shot.
Of course, the distance of your strobe from your subject has other effects than just the incident power. If you are using a softbox or other light diffusor, the closer you set you source to your subject, the softer the light. The converse is also true.
Tjhere are a number of other factors that are involved in the final lighting. All of them are important.
Photographer
Marvin Dockery
Posts: 2243
Alcoa, Tennessee, US
Ron Blouch wrote:
Hi,
After reading many, many questions, answers and what not I am interested in why photographers almost always describe their lighting set ups as I set my power light at half power or quarter power or 500 watts. What does this mean?
I feel if you want to describe your lighting speak in f stops. As an example: I set the key light at f8 and the fill at 5.6. Now I know how you actually lighted the subject.
When I hear the power numbers 1000w,500w etc. it really does not tell me anything. At 1000w how close is the key light? 5 feet, 10 feet from the subject. If you move the key light away or closer to the subject the power will change accordingly. So telling me how much power you are using does tell me much of anything.
Just thought I would throw this out. Maybe my thinking is all wrong. F. 5.6 and f 8 refers to what the lens is set at, not light out put from a strobe.
When someone says that their strobe is 2400 watts, they mean that the strobe could put out 2400 watts. 1/2 power would be 1200 watts. If four lights are plugged into a 2400 watt power pack, each light would put out 600 watts. Some strobes have adjustments down to almost nothing.
The amount of dept of field needed, in a given photo, decides the f stop you need to use.. Then the strobe is adjusted to put out the right amount of light, using a flash meter, or if you are shooting digital, looking at images on your computer.
I use computer checks and flash meters.
The problem you are having is lack of experence, and lighting knowledge. This is not a put down, since all of us have been where you are at at one time.
There should be some good books on lighting, strobes, hotlights, and available light, at Barnes and Noble.
Photographer
Simon Gerzina
Posts: 2288
Brooklyn, New York, US
Marvin Dockery wrote:
F. 5.6 and f 8 refers to what the lens is set at, not light out put from a strobe. Well, it's also the incident meter reading from a particular place of a particular amount of light at a particular shutter speed and ISO rating combination. You can set your lens to whatever you want, but that's how much light is seen to be landing somewhere, as opposed to how much light a fixture is putting out. So, as such, it's a very useful way of describing the lighting of a scene, and it's how I've generally seen working pros of various stripes chart and describe setups ("I want the key light to be f/8 on the bridge of her nose and no more than 1/3-stop less on the rest of her face, I want the floor at f/11 evenly, I want everything from her collarbone down at f/7, keep playing with the background accent lights until you get f/16 peaks that drop off to f/5.6 within a couple feet...").
In assisting or working on sets I've never heard a photographer say "I want this head at full power, this one at 500ws, those three back there at half power..."
Photographer
Yuriy
Posts: 1000
Gillette, New Jersey, US
Simon A Gerzina wrote:
I think that part of the problem is that a lot of digital photographers, especially less-experienced ones, don't shoot with light meters...so they don't know what each light meters at, they only know what the turned the knob on their monolights to. Further, I think many of them have only experienced their own lighting gear, so they don't understand that "half-power" on a 320ws Alien Bee unit is totally different than "half-power" on a 2400ws Profoto pack that's driving 3 heads asymmetrically with a second pack driving another 2 heads. Or, like you pointed out, "half-power" means something different when your light is 10' away from a model vs. 10" away. Haha! Good laugh to start the day lol.
Marvin Dockery wrote:
F. 5.6 and f 8 refers to what the lens is set at, not light out put from a strobe.
When someone says that their strobe is 2400 watts, they mean that the strobe could put out 2400 watts. 1/2 power would be 1200 watts. If four lights are plugged into a 2400 watt power pack, each light would put out 600 watts. Some strobes have adjustments down to almost nothing.
...
There should be some good books on lighting, strobes, hotlights, and available light, at Barnes and Noble.
... But in actuality those numbers are also inaccurate since they describe the efficiency of the system.
Really if you're strobe shopping then Guide Numbers would be what you would use to determine aperture @ distance.
Other than that, (I believe someone already stated this) you are only looking for ratios.
Barnes and Noble is way too expensive for photography books. I would suggest Amazon (believe it or not). The best thing would be to sit down with other photographers and "talk shop".
Photographer
Ron Blouch
Posts: 34
Harrisburg, Pennsylvania, US
I understand the various lighting setup. I was simply using f8 and 5.6 as example of a light set up. You are correct that this is showing the light falling on the subject. It is also showing the ratio of the key and fill light. The only point I was trying to make was that when you tell me what watts you are using it does not tell me anything about the actual light on the subject except for that particular photographer and their lights on the subject.
Would you know if a photographer told you he used half power of his lights what f stop you should use? As you are aware the longer you use the lights the weaker the output because of old age so half power is different later on with that light.
Photographer
Ron Blouch
Posts: 34
Harrisburg, Pennsylvania, US
Thank you Simon you stated what I was trying and you did it alot easier than I did
Photographer
Charlie Schmidt
Posts: 856
Kansas City, Missouri, US
Simon A Gerzina wrote:
In assisting or working on sets I've never heard a photographer say "I want this head at full power, this one at 500ws, those three back there at half power..." I have heard this form of expression use for lighting many times, it does seem to be the "older" photographers, and I believeas they got to know their studio and their lighting setups, they knew what power settings would yeald what look.
Have a Great Day
Charlie
Photographer
Giacomo Cirrincioni
Posts: 22234
Stamford, Connecticut, US
Marvin Dockery wrote:
F. 5.6 and f 8 refers to what the lens is set at, not light out put from a strobe.
When someone says that their strobe is 2400 watts, they mean that the strobe could put out 2400 watts. 1/2 power would be 1200 watts. If four lights are plugged into a 2400 watt power pack, each light would put out 600 watts. Some strobes have adjustments down to almost nothing.
The amount of dept of field needed, in a given photo, decides the f stop you need to use.. Then the strobe is adjusted to put out the right amount of light, using a flash meter, or if you are shooting digital, looking at images on your computer.
I use computer checks and flash meters.
The problem you are having is lack of experence, and lighting knowledge. This is not a put down, since all of us have been where you are at at one time.
There should be some good books on lighting, strobes, hotlights, and available light, at Barnes and Noble. Also, not meaning to put you down, but I think you're wrong. There are many ways to reference light output, however most professionals speak in f-stops or EV. As the OP stated, power output of the lamp means nothing, unless you are also providing a detailed lighting diagram with exact lamp placement measured out to scale, brand of light used and age of the lamp - and even then it will just be an approximation. Depth of field is an independent topic, for the most part. You can create a lighting setup that you like and use it for both shallow and deep shots. As long as the light ratios are the same, all you have to adjust is the over all power output. Well that's what you're saying right? Not really. If you really want to discuss a lighting setup, you should note what the ISO is and what your camera exposure is set as (shutterspeed and f/stop). Then you would independently meter each light and provide the reading for each light (or reflector). Because gear can vary so dramatically you may wish to note the flash readings as EV instead, but f/stops work fine. Armed with this information (and the general light placement in degrees) you or anyone else can recreate the lighting setup with any brand of lighting (assuming it is fundamentally up to the task).
To the original posters point, I agree that many reasons for this are digital guys who work without a meter, but also many pack guys (and these are usually very experienced shooters) will speak this way as their equipment is well tuned and they are essentially speaking in EV and describing the ratio. What the actual power output of the Key light is is not very important. But to know that they have their fill light set to half the output of the key is valuable information. But I agree, speaking in f/stops is most useful when describing a lighting setup if the intent is to be able to recreate the shot.
Best,
Matthew
Photographer
VRG Photography
Posts: 1025
Tallahassee, Florida, US
I've been shooting film for over 15 years, and I never used the power of the strobes to set my lighting. I almost always metered. The subject and background would either be the same, or a stop off, so that I could separate one from the other, depending on the effect I was going for.
When you start moving strobes around, you should be thinking "metering," and not "power," or you'll be screwed up ROYALLY.
If you're shooting with digital, you can recover a bit quicker than with film.
Bottomline: Think f-stop. You can't go wrong there, no matter WHAT lights you use.
Photographer
northern clicker
Posts: 159
Anchorage, Alaska, US
Lens N Light wrote:
If you are using a softbox or other light diffusor, the closer you set you source to your subject, the softer the light. The converse is also true. Buehler? Anybody? I thought FARTHER away made softer light? Not with a softbox? Whaaaa??
Photographer
Tog
Posts: 55204
Birmingham, Alabama, US
Well, I set my key light to 4000 watts so I could vaporize the model into a puff of smoke.. My fill was set at 1000 watts so that the smoke would be highlighted against the dark background.. And of course I used a snoot on the hairlight so I could suck up the smoke cloud/model in case I needed to get a release signed later..
Any questions?
Photographer
Analog Nomad
Posts: 4097
Pattaya, Central, Thailand
northern clicker wrote:
Buehler? Anybody? I thought FARTHER away made softer light? Not with a softbox? Whaaaa?? Nope -- the closer the light, with any light, the softer it gets. Don't confuse intensity with softness. Putting a light really close can lead to overexposure, which certainly doesn't look soft. But assuming proper exposure, getting a softbox REALLY close produces REALLY soft light. It's a beautiful thing. . .
Real softness seems to happen when the light becomes physically larger than the subject. Conversely, the more the light becomes like a point source, the harder it becomes.
Photographer
Hoodlum
Posts: 10254
Sacramento, California, US
northern clicker wrote:
Buehler? Anybody? I thought FARTHER away made softer light? Not with a softbox? Whaaaa?? No the size of the light source in proportion to the subject determines the softness of the light. A softbox is soft because it makes the light source act as a larger light source.
For example take a softbox and light a apartment building from 250' away (pretend your strobe could do it) the light will be hard whether or not a softbox is used as it is the ratio of the light source to the subject. Take the same soft box and put it 2' from say a coffee cup and the light will be really soft.
Real simply the closer (or larger) the light is the softer it will be to the subject.
P.S there are lots of good books on the basics of lighting.
Photographer
Giacomo Cirrincioni
Posts: 22234
Stamford, Connecticut, US
northern clicker wrote:
Buehler? Anybody? I thought FARTHER away made softer light? Not with a softbox? Whaaaa?? Soft vs. Hard is based on the size of the light source in relation to the size of the object being lit. The larger the source, the softer the light. When the soft box is placed closer to your subject it is relatively larger than if it is placed much further away. So (if we assumed clear skies and each planet had atmospheres identical to Earth's) Mercury would have the softest sunlight in the solar system and pluto would have the hardest light. Get it? It's easy to test out, pull out your soft box and give it go. There is also a mathematical way to figure out the ideal distance based on box size, but a quickie rule of thumb is size of box (diagonal)=distance to subject. So for example the "ideal" distance of a 5' box would be roughly 5' from the subject. I don't know if I totally buy into that, and like to place lights differently, but it does give you a good starting point.
Matthew
Photographer
northern clicker
Posts: 159
Anchorage, Alaska, US
Okay! and thanks, folks. I'd lost my way, confused by the difference between SIZE and DISTANCE in relation to 'point source' blah blah... was thinking that farther meant bigger, and therefore better... got it backwards. And that explains a problem I'd just had in moving my lights further! D'Oh! I've GOT lots of books on lighting... just a bad brain fart... let me fan that away... and sorry for the small hijack...
Photographer
Marvin Dockery
Posts: 2243
Alcoa, Tennessee, US
Paramour Productions wrote:
Also, not meaning to put you down, but I think you're wrong. There are many ways to reference light output, however most professionals speak in f-stops or EV. As the OP stated, power output of the lamp means nothing, unless you are also providing a detailed lighting diagram with exact lamp placement measured out to scale, brand of light used and age of the lamp - and even then it will just be an approximation. Depth of field is an independent topic, for the most part. You can create a lighting setup that you like and use it for both shallow and deep shots. As long as the light ratios are the same, all you have to adjust is the over all power output. Well that's what you're saying right? Not really. If you really want to discuss a lighting setup, you should note what the ISO is and what your camera exposure is set as (shutterspeed and f/stop). Then you would independently meter each light and provide the reading for each light (or reflector). Because gear can vary so dramatically you may wish to note the flash readings as EV instead, but f/stops work fine. Armed with this information (and the general light placement in degrees) you or anyone else can recreate the lighting setup with any brand of lighting (assuming it is fundamentally up to the task).
To the original posters point, I agree that many reasons for this are digital guys who work without a meter, but also many pack guys (and these are usually very experienced shooters) will speak this way as their equipment is well tuned and they are essentially speaking in EV and describing the ratio. What the actual power output of the Key light is is not very important. But to know that they have their fill light set to half the output of the key is valuable information. But I agree, speaking in f/stops is most useful when describing a lighting setup if the intent is to be able to recreate the shot.
Best,
Matthew My strobes do not have f stops on them, but my lenses do. My strobes have power settings, and movable light stands for fine tuning. I set my working f stop, then adjust my strobes to give me to give me the proper exposure at the chosen f stop. I also decide the ratio between my main, fill, and background lights.
Ratios between highlights and shadows can be from 1:1 to 1 :1000 for film, but not for digital.
I shoot one ratio for film, and then a different ratio for digital.
Photographer
Gary Davis
Posts: 1829
San Diego, California, US
My strobes have a self contained nuclear reactor to produce 1.21 gigawatts of power which is stored in a flux capacitor. It recycles in 1ms 
Photographer
Simon Gerzina
Posts: 2288
Brooklyn, New York, US
Gary Davis wrote:
My strobes have a self contained nuclear reactor to produce 1.21 gigawatts of power which is stored in a flux capacitor. It recycles in 1ms No shit. Can I borrow them? Send 'em back in time to me so I can have 'em for yesterday's shoot, please. 
Marvin Dockery wrote:
My strobes do not have f stops on them, but my lenses do. My strobes have power settings, and movable light stands for fine tuning. I set my working f stop, then adjust my strobes to give me to give me the proper exposure at the chosen f stop. I also decide the ratio between my main, fill, and background lights. No one's lights have f-stop markings on them, because they don't have apertures on them. The f-stop isn't the measure of the output of your lights, it's the measure of the amount of light your camera's film plane (or sensor) will receive based on the amount of light reflected by an object assumed to be 18% grey...AKA your subject, or part of it. Well, technically it's not even that, but that's what people use it as shorthand for when talking about lighting vs. lensing.
Talking about what you set the output of your lights to in a setup is irrelevant unless we also have exactly the same lights as you do, exactly the same modifiers as you do, know exactly where you positioned them relative to exactly everything else. So, instead of assuming or relating all those things, we simply talk about the amount of light that strikes the subject in various places as measured in f-stops, just like a light meter tells you.
If you hold a light meter up to your subject, set the ISO rating and shutter speed and take a reading it doesn't tell you "oh, that's a Calumet Travellite 750 set to 3/4 power from 15' away through a double-diffused 5' octadome"...it says f/5.6. So someone asks you "how did you light that?" and you say "a beauty dish keying the right side of her face from 45 degrees above and reading f/8, a hairlight at one stop over that, background lights at f/5.6..." etc. Because that actually explains how to achieve the lighting scheme.
Not sure why that's so complicated. It's how it's been explained in every studio, class, lighting book, film set, video shoot, magazine article that I've experienced. I have to think that's the norm.
Photographer
Gary Davis
Posts: 1829
San Diego, California, US
Simon A Gerzina wrote:
No shit. Can I borrow them? Send 'em back in time to me so I can have 'em for yesterday's shoot, please. sorry, the delorean's in the shop 
Photographer
Marvin Dockery
Posts: 2243
Alcoa, Tennessee, US
Simon A Gerzina wrote:
Gary Davis wrote:
My strobes have a self contained nuclear reactor to produce 1.21 gigawatts of power which is stored in a flux capacitor. It recycles in 1ms No shit. Can I borrow them? Send 'em back in time to me so I can have 'em for yesterday's shoot, please.
No one's lights have f-stop markings on them, because they don't have apertures on them. The f-stop isn't the measure of the output of your lights, it's the measure of the amount of light your camera's film plane (or sensor) will receive based on the amount of light reflected by an object assumed to be 18% grey...AKA your subject, or part of it. Well, technically it's not even that, but that's what people use it as shorthand for when talking about lighting vs. lensing.
Talking about what you set the output of your lights to in a setup is irrelevant unless we also have exactly the same lights as you do, exactly the same modifiers as you do, know exactly where you positioned them relative to exactly everything else. So, instead of assuming or relating all those things, we simply talk about the amount of light that strikes the subject in various places as measured in f-stops, just like a light meter tells you.
If you hold a light meter up to your subject, set the ISO rating and shutter speed and take a reading it doesn't tell you "oh, that's a Calumet Travellite 750 set to 3/4 power from 15' away through a double-diffused 5' octadome"...it says f/5.6. So someone asks you "how did you light that?" and you say "a beauty dish keying the right side of her face from 45 degrees above and reading f/8, a hairlight at one stop over that, background lights at f/5.6..." etc. Because that actually explains how to achieve the lighting scheme.
Not sure why that's so complicated. It's how it's been explained in every studio, class, lighting book, film set, video shoot, magazine article that I've experienced. I have to think that's the norm. I understand what you are saying, and I am sure it the norm.
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