Strobes watts/sec...What does that mean in output?

[BLD_007]

So I'm looking at getting some strobes for portrait work and other applications.

For every 100watts, do you gain 10feet in light output or something like that?.

 

[Big Mike]

It's not that simple.

Strobes are usually rated in Watt Seconds (Ws). The more Watt Seconds, the more power/energy is being released when it fires.

That doesn't directly relate to photography terms though. The actual output of light will depend on the design on the light and whatever modifiers are used. For example, you may get more light (to a certain area) with a softbox, than with an umbrella. You will get even more with a reflector dish, but the light will be harder.

So a strobe with more Watt seconds, will output more light, which can give you more range, or allow you to shoot with smaller apertures, but the exact amount will depend on the modifiers.

A flash unit, on the other hand, is usually rated by a Guide Number (GN). This is because they are often used without modifiers and have a built in reflector dish and lens. The GN divided by the distance to the subject, will give you the F number needed for proper exposure.

 

[Alpha]

For clarification, a watt*second is a joule, which is a unit of energy, not power.

Also, strobes technically have guide numbers, too.

Anyway, I'd aim for something in the 600w/s neighborhood. 300 can leave you feeling limited, and 1200+, for the average photographer's uses, is overkill.

 

[Big Mike]

For clarification, a watt*second is a joule, which is a unit of energy, not power.

Ah yes, thank you.

Also, strobes technically have guide numbers, too.

Yes, but pretty much need to specify the modifier to go along with a given GN. For example, you might say it has a GN of 100m, with standard/stock reflector. Of course, a bare strobe will have a GN, but that's not typically how you'd use it, so it doesn't mean much, IMO.

 

[BLD_007]

I just don't want to run into the problem of not having enough power if the strobe needs to be mounted somewhere.

 

[Alpha]

What do you mean by, "if the strobe needs to be mounted somewhere" ?

 

[BLD_007]

What do you mean by, "if the strobe needs to be mounted somewhere" ?

ceiling of an arena for basketball tournaments or a ceiling of a gym for normal basketball games. In other words, far away and not close up.

 

[KmH]

What do you mean by, "if the strobe needs to be mounted somewhere" ?

ceiling of an arena for basketball tournaments or a ceiling of a gym for normal basketball games. In other words, far away and not close up.

That means the "Inverse Square Law" comes into play.

Light falls off as a square function to distance. If you double the distance to the subject, only 1/4 as much light reaches the subject. If you double the distance again only 1/16th as much light reaches the subject.

 

[JimmyO]

So I'm looking at getting some strobes for portrait work and other applications.

For every 100watts, do you gain 10feet in light output or something like that?.

I feel like everytime you post your getting ahead of yourself. Last week your were asking whats a fast lens now you have all L lenses and think you know what your talking about with strobeing a basketball game but your making yourself look dumb.

 

[BLD_007]

So I'm looking at getting some strobes for portrait work and other applications.

For every 100watts, do you gain 10feet in light output or something like that?.

I feel like everytime you post your getting ahead of yourself. Last week your were asking whats a fast lens now you have all L lenses and think you know what your talking about with strobeing a basketball game but your making yourself look dumb.

I have always had L. I have had my 70-200L for over a year. I just got my 24-70 about two months ago.

Don't call me dumb, I know more than you think.

I also have strobed basketball, diving, and dodge ball games. The thing is, I have not used my own strobes. I have always used the schools strobes. I want to get my own now. I just want to buy the most powerful ones that I can. I don't want to buy too weak and wish I had more.

 

[BLD_007]

So I'm looking at getting some strobes for portrait work and other applications.

For every 100watts, do you gain 10feet in light output or something like that?.

I feel like everytime you post your getting ahead of yourself. Last week your were asking whats a fast lens now you have all L lenses and think you know what your talking about with strobeing a basketball game but your making yourself look dumb.

I also have always know that the lower the apature the more light that hits the sensor. Last week I asked why it was called "fast" the term fast. Why FAST was used.

 

[Village Idiot]

So I'm looking at getting some strobes for portrait work and other applications.

For every 100watts, do you gain 10feet in light output or something like that?.

I feel like everytime you post your getting ahead of yourself. Last week your were asking whats a fast lens now you have all L lenses and think you know what your talking about with strobeing a basketball game but your making yourself look dumb.

He's posting legit questions. You're making yourself look like an ass, as usual.

 

[Pure]

I'm going to sound like a huge idiot, but please spare me, I never use strobes...yet.

Lets say you have two identical strobes except their W/s power. One is 1600W/s and the other is 800W/s. Same modifiers, etc.

If you shoot the 800W/s strobe at 1/1 and the 1600W/s strobe at 1/2, will the output be the same?

 

[Sw1tchFX]

I'm going to sound like a huge idiot, but please spare me, I never use strobes...yet.

Lets say you have two identical strobes except their W/s power. One is 1600W/s and the other is 800W/s. Same modifiers, etc.

If you shoot the 800W/s strobe at 1/1 and the 1600W/s strobe at 1/2, will the output be the same?

yes.

 

[JimmyO]

So I'm looking at getting some strobes for portrait work and other applications.

For every 100watts, do you gain 10feet in light output or something like that?.

I feel like everytime you post your getting ahead of yourself. Last week your were asking whats a fast lens now you have all L lenses and think you know what your talking about with strobeing a basketball game but your making yourself look dumb.

He's posting legit questions. You're making yourself look like an ass, as usual.

o rly

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