Pros and cons of flash vs constant lighting and more ?

I think constant lights are more power effective.
would you please explain that?

Yeah, I lol'd. I have no idea what his definition of 'power effective' is, but I can't imagine any remotely plausible meaning of the term where that statement is true.
 
I think constant lights are more power effective.
Constant lights are slow.

A 200 watt constant light delivers the 200 watts in one second. If you use a shutter speed of 1/100 second, the constant light only delivers 2 watts during the exposure, wasting 180 watts in the second the light was on for the exposure, and wasting 200 watts for each additional second the light is on when you're not taking photos.

A constant light cannot be used to stop motion like a strobe light (flash) can.

Constant lighting adds to the ambient light in a scene and the constant light cannot be controlled separate from the ambient light the way strobed light can.

Not that I care, but I keep seeing this math...and it does not seem accurate. A 200 Watt bulb puts out....wait for it,wait for it...200 Watts. The time the shutter is open does NOT change the output of the bulb. The idea that the duration the shutter is open actually seems to me to be a seriously flawed bit of "logic". I mean, I understand where you are coming from, but the logic is seriously,seriously FLAWED. For example, let's take the noon-day sun in Los Angeles on July 4th. The sun is bright that day. If I open my eyes for one second....that does NOT make the sun "dimmer" than if I keep my eyes open for five minutes while I run down to Starbucks to get a coffee. I understand why some people use the example under discussion, but it seems just wrong to me to make statements that are entirely inaccurate.

If I weigh 250 pounds, but stand on ONE FOOT, do I therefore weigh 125 pounds? If I have a gallon of water, but put it into FOUR, separate, 32-ounce plastic bottles, do I somehow magically have LESS THAN a gallon of water??? if I have a 500 Watt flood light, its output is ALWAYS 500 Watts...that's the way that works...

I believe the premise being used is flawed from the very core. The concept stated above is that a 200 Watt bulb puts out 200 Watts in one second....uh...that's not the way I understand it...it's not based on TIME....there is absolutely ZERO "time element"....Wattage is based on how MUCH light is put out. I wonder if maybe I could read a book using three, 10-Watt night lights if I just sat there in the dark and waited long enough...hmmm...
 
For a hobbyist, I actually don't think the Cowboy studio stuff is that bad.
 
I think constant lights are more power effective.
Constant lights are slow.

A 200 watt constant light delivers the 200 watts in one second. If you use a shutter speed of 1/100 second, the constant light only delivers 2 watts during the exposure, wasting 180 watts in the second the light was on for the exposure, and wasting 200 watts for each additional second the light is on when you're not taking photos.

A constant light cannot be used to stop motion like a strobe light (flash) can.

Constant lighting adds to the ambient light in a scene and the constant light cannot be controlled separate from the ambient light the way strobed light can.

Not that I care, but I keep seeing this math...and it does not seem accurate. A 200 Watt bulb puts out....wait for it,wait for it...200 Watts. The time the shutter is open does NOT change the output of the bulb. The idea that the duration the shutter is open actually seems to me to be a seriously flawed bit of "logic". I mean, I understand where you are coming from, but the logic is seriously,seriously FLAWED. For example, let's take the noon-day sun in Los Angeles on July 4th. The sun is bright that day. If I open my eyes for one second....that does NOT make the sun "dimmer" than if I keep my eyes open for five minutes while I run down to Starbucks to get a coffee. I understand why some people use the example under discussion, but it seems just wrong to me to make statements that are entirely inaccurate.

If I weigh 250 pounds, but stand on ONE FOOT, do I therefore weigh 125 pounds? If I have a gallon of water, but put it into FOUR, separate, 32-ounce plastic bottles, do I somehow magically have LESS THAN a gallon of water??? if I have a 500 Watt flood light, its output is ALWAYS 500 Watts...that's the way that works...

I believe the premise being used is flawed from the very core. The concept stated above is that a 200 Watt bulb puts out 200 Watts in one second....uh...that's not the way I understand it...it's not based on TIME....there is absolutely ZERO "time element"....Wattage is based on how MUCH light is put out. I wonder if maybe I could read a book using three, 10-Watt night lights if I just sat there in the dark and waited long enough...hmmm...

Wattage is in fact a time based unit. it's one Joule/sec
 
So, if I sit in the near-dark for six hours with three, 10-Watt bulbs I will be able to read the book???
 
So, if I sit in the near-dark for six hours with three, 10-Watt bulbs I will be able to read the book???

No, because your eyes work differently than a camera. If you sit a camera in there with the shutter open that long, then I imagine that you wouldn't be able to read the book, because it would have too much light. (well, obviously depending on your settings. It might be possible with some combo of base ISO, stopped down aperture and ND filters to get a workable exposure in 3 hours of three 10 watt bulbs, but IDK exactly what the numbers would be)
 
In addition to what Derrel wrote, may I suggest some changes:

Constant light power is rated in watts. A watt is one joule of power per second.

A watt is one joule of energy per second. A watt is a unit of power - though we often refer to 'powerful' strobes when we are referring to energy (watt seconds = joules) instead of power.

If you use a 500 watt constant light and a shutter speed of 1 second, you use all 500 watts. If you use a 500 watt constant light and a shutter speed of 1/100 of a second you only use 5 watts of the 500 watts the light makes in 1 second.

A 500 W constant light is always using 500 W, no matter what the shutter speed is. In 1 s it uses 500 J (joules). In 1/100 s it uses 5 J, but still 500 W.

Wattage is not the best indicator of light output, because different types of light source put out different light powers (lumens) for the same electrical power input (in watts). The lumens/watt ratio varies dramatically.

Strobed light is flash, and constant light is ambient light, so mixing the 2 can be done but the camera's shutter speed controls the ambient light exposure, while the lens aperture controls the strobed light exposure.

Exactly. I do that quite a lot. It's a useful technique.
 
I think HelenB has better-articulated the idea that I tried so poorly to communicate...but dammnit!!! i am OUT OF FREAKING COFFEE and my brain is in 1st gear....
 
In addition to what Derrel wrote, may I suggest some changes:

Constant light power is rated in watts. A watt is one joule of power per second.

A watt is one joule of energy per second. A watt is a unit of power - though we often refer to 'powerful' strobes when we are referring to energy (watt seconds = joules) instead of power.

If you use a 500 watt constant light and a shutter speed of 1 second, you use all 500 watts. If you use a 500 watt constant light and a shutter speed of 1/100 of a second you only use 5 watts of the 500 watts the light makes in 1 second.

A 500 W constant light is always using 500 W, no matter what the shutter speed is. In 1 s it uses 500 J (joules). In 1/100 s it uses 5 J, but still 500 W.

Wattage is not the best indicator of light output, because different types of light source put out different light powers (lumens) for the same electrical power input (in watts). The lumens/watt ratio varies dramatically.

Strobed light is flash, and constant light is ambient light, so mixing the 2 can be done but the camera's shutter speed controls the ambient light exposure, while the lens aperture controls the strobed light exposure.

Exactly. I do that quite a lot. It's a useful technique.

Right, it is always at 500W, but the amount of light put out by the light varies by the amount of time the camera is exposed to it. I think I'm seeing the issue, KmH said it produces 2 watts, which is obviously wrong. I think he meant the brightness equivalent of 2 Watts over 1 second. Yeah, Derrel, you are right, I was just thrown off by you saying 'it has no time element'. which isn't correct.

It has a time element, it's just that by reducing the numerator, you also reduce the denominator, so the wattage is constant.
 
I think HelenB has better-articulated the idea that I tried so poorly to communicate...but dammnit!!! i am OUT OF FREAKING COFFEE and my brain is in 1st gear....

Ha, yeah, I get what you were saying now. I also had sort of fixed what KmH was saying in my head without realizing what he said was technically wrong. I didn't realize he said it was 2 watts until I just re-read his post.
 
in other words: it's funny how a 20w CFL produces the equivalent amount of light as a 75w incandescent bulb.
 
in other words: it's funny how a 20w CFL produces the equivalent amount of light as a 75w incandescent bulb.

Yeah, as Helen was saying, wattage is a terrible way to measure things for photographers, since it sort of assumes the same level of efficiency. Some lights are more efficient at getting you photons per watt into the camera.
 
But KmH isn't entirely wrong. The amount of energy which accumulates at the film plane can be measured. While a 500w source always pulls 500w, the amount of that energy that can be recorded depends on exposure time, and this energy can be measured in watt/time. But as Helen points out, not all of the energy which the lamp consumes can be converted into light. Some of it is also lost in heat. This is why incandescent is so inefficient, more of the light radiated from a heated filament will be in the invisible part of the spectrum.

In fact, an incadescent blacklight bulb is just a regular bulb that has been filtered, and there is STILL enough energy to cause fluorescence and violet light illumination.
 
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But KmH isn't entirely wrong. The amount of energy which accumulates at the film plane can be measured. While a 500w source always pulls 500w, the amount of that energy that can be recorded depends on exposure time, and this energy can be measured in watt/time.

Right, I think we all understood the spirit of what KmH was trying to say, and that being correct. I think they were just pointing out it was technically incorrect.
 

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