Lighting Power

Curtis N wrote in post #2704376
I don't own any studio strobes yet, but that seems like a lot.

Admittedly, the only brand I have studied in any detail is AlienBees, which I understand are not in the "high power" category where studio strobes are concerned. But their most powerful unit is only 640 watt-seconds, and according to their specs it will give you f/11 to f/16 with a shoot-through umbrella at a distance of 10 feet.

Maybe you would want more than that for location group shots, but would you really need that kind of power in a typical portrait studio?

In practical terms 800 Ws or 640 Ws are the same. Only about 1/4 of a stop difference, an insignificant amount.

The OP specifically mentioned 800 Ws and if that was enough, so I though 800 Ws a reasonable place to hang your hat. This is not a situation where exactness is of total importance.

The big point for me is that if you go with monolights, that a grand collection of several monolight, without any one being very powerful is a mistake. I have seen several inexpensive monolight sets that indicate a total of some reasonable value, say 400 Ws, but individually no unit has more than 150 Ws.

For general photography there are a lot of times you want to use only one flash, so if they are all anemic, this is an issue. This is one of the upsides of the power pack/flash head systems. All of the power you have can be utilized in only one head (or divided between several). But, monolights have other desirable upsides.

Enjoy! Lon

Power requirements vary enormously depending on what light modifiers you use, the distance from light to subject, and the aperture required. I have done head and shoulders shots at f/4 that only required 400ws distributed among 3 heads, and I have done room sets that required over 12,000ws in order to light large areas and still shoot at f/22 for depth of field.

Remember that for every increase in f/stop, you must double the light output. So if 100ws gives you f/4, then to get f/22 you need 3200ws. And doubling the flash-to-subject distance requires 4 times the output due to the inverse-square property of light. So shooting at f/22 with a light 5-7 meters away from the subject is going to require far more watt-seconds than most monolights are capable of.

chtgrubbs wrote in post #2713463
Power requirements vary enormously depending on what light modifiers you use, the distance from light to subject, and the aperture required. I have done head and shoulders shots at f/4 that only required 400ws distributed among 3 heads, and I have done room sets that required over 12,000ws in order to light large areas and still shoot at f/22 for depth of field.

Remember that for every increase in f/stop, you must double the light output. So if 100ws gives you f/4, then to get f/22 you need 3200ws. And doubling the flash-to-subject distance requires 4 times the output due to the inverse-square property of light. So shooting at f/22 with a light 5-7 meters away from the subject is going to require far more watt-seconds than most monolights are capable of.

And when i talked to many that i want to use f11-f22 with ISO50-200 they keep saying that i don't need more than 600 or 800w.s, there is one man in Betterphoto website answered me many times that i have to study lightings before i waste money to get lighting power more than 1000w.s, and i can do great with only 400-800 and i have to use available light and so, and i told him many times that i want to use f22 and iso 50 or 100 but he keep telling me that i should go and study better than thinking of lighting more than 1000w.s or 800w.s, i hope he didn't get me wrong or i didn't get him wrong

f/22 does seem like overkill to me. Even for multi-row group shots, the focal length and distance you use for such shots will generally put you past the hyperfocal distance at f/11.

Further, I don't think there is any image quality advantage in using ISO 50 vs. ISO 100. Even ISO 200 is unlikely to create any noticeable degradation in image quality.

Now there is a four-stop difference between f/22, ISO 50 and f/11, ISO 200. Using the former combination will multiply your light requirement by a factor of 16 without generating a better image. Perhaps this is why others are suggesting to invest minimally at first. When you learn to overcome the challenges inherent in having less light, you will be better qualified to make wise buying choices down the road.

Curtis N wrote in post #2713940
f/22 does seem like overkill to me. Even for multi-row group shots, the focal length and distance you use for such shots will generally put you past the hyperfocal distance at f/11.

Further, I don't think there is any image quality advantage in using ISO 50 vs. ISO 100. Even ISO 200 is unlikely to create any noticeable degradation in image quality.

Now there is a four-stop difference between f/22, ISO 50 and f/11, ISO 200. Using the former combination will multiply your light requirement by a factor of 16 without generating a better image. Perhaps this is why others are suggesting to invest minimally at first. When you learn to overcome the challenges inherent in having less light, you will be better qualified to make wise buying choices down the road.

I tried to shoot my daughter with F4 and ISO 1000 in natural light and the pic was underexposure, in all cases i know myself when i get a power of 400 or 600 then find out that it is not enough for even on time then i will go to buy more power light, so as it is said, keep myself at high side than low side.

I have a studio setup that consist of two Utrazap 1600 strobes for main and fill, one Ultrazap 800 for a background light, and I use a 540EZ as a hairlight with a Wein Peanut Slave. That kit gives me plenty of light to do whatever I need in a studio setting. The UZ 1600's are 660 true W-S strobes, and the UZ 800 is a 330 true W-S strobe. That gives me a total of 1650 W-S of power to play with. For normal portraits and or small group shots, this is plenty, but I wouldn't want any less either, since, as someone already mentioned, it's better to have more power available and not use it than to not have enough power available at all.

Mark

Mark_Cohran wrote in post #2714101
I have a studio setup that consist of two Utrazap 1600 strobes for main and fill, one Ultrazap 800 for a background light, and I use a 540EZ as a hairlight with a Wein Peanut Slave. That kit gives me plenty of light to do whatever I need in a studio setting. The UZ 1600's are 660 true W-S strobes, and the UZ 800 is a 330 true W-S strobe. That gives me a total of 1650 W-S of power to play with. For normal portraits and or small group shots, this is plenty, but I wouldn't want any less either, since, as someone already mentioned, it's better to have more power available and not use it than to not have enough power available at all.

Mark

great, thank you.
that what i look for

Tareq wrote in post #2714044
I tried to shoot my daughter with F4 and ISO 1000 in natural light and the pic was underexposure, in all cases i know myself when i get a power of 400 or 600 then find out that it is not enough for even on time then i will go to buy more power light, so as it is said, keep myself at high side than low side.

Tareq,
You mention you used F4 and ISO 1000 and underexposed ...
You were shooting in aperture or Manual mode ?
What shutter speed did you get/dialed ?

Velu wrote in post #2714318
Tareq,
You mention you used F4 and ISO 1000 and underexposed ...
You were shooting in aperture or Manual mode ?
What shutter speed did you get/dialed ?

in Manual mode.
i remember i use 1/250
but even if i use 1/60 or 1/80, with F4 and ISO 1000 i should use 1/100 without any Fear, and that natural light was behind window with very light curtain which play as softbox, in Day time, i should think it is enough strong, so what do you think? I don't want to use ISO above 400 even i should do or i can, i want to keep my ISO as low as i can, and F4 just to blur the Background because in the room with many distracting things around, but sure i need to shoot F11-F22 in many cases, about shutter speed doesn't matter but i want to keep above 1/60 to be sure no blur at all if i use Non IS lens.
I don't know why many people asking me to use settings that i can do but i don't want to use it just to make power light as low as i can.