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I don't know how best to word this I'm afraid so you'll have to bear with my pigeon photography speak.

I was wondering what the output watts of an SB800 were. I mean, is it equivalent to a 100w lightbulb, or a 500w bulb etc?

I want to get some cheap studio lights and I was thinking that a builders halogen light might be a good idea until I get some more funds.
So would the light from a 500w haligen builders light be as bright as that from an SB800?

Cheers

Also, what does it mean when you dial down to about 1/32 power? Does that mean you still have the same intensity of light but only for 1/32 of the time?

Hi Matt,

I cant answer the 'equivilent light outputs' question, but for your other question, the 1/32 is a function of power output, not time of output.

rokkstar wrote:I don't know how best to word this I'm afraid so you'll have to bear with my pigeon photography speak.

I was wondering what the output watts of an SB800 were. I mean, is it equivalent to a 100w lightbulb, or a 500w bulb etc?

I want to get some cheap studio lights and I was thinking that a builders halogen light might be a good idea until I get some more funds.
So would the light from a 500w haligen builders light be as bright as that from an SB800?

Cheers

Better to think of the output in Joules...

A watt is a Joule per second.. so for a very shot about of time the wattage is very high (if you assume that the flash is going to keep emitting) however the length of the pulse is short... so over, say a second, the wattage would be low...

rokkstar wrote:Also, what does it mean when you dial down to about 1/32 power? Does that mean you still have the same intensity of light but only for 1/32 of the time?

Correct me if I'm wrong but it should affect both - power and duration. Here is a table from SB800 manual:
1/1050 sec. at M 1/1 (full)
1/1100 sec. at M 1/2 output
1/2700 sec. at M 1/4 output
1/5900 sec. at M 1/8 output
1/10900 sec. at M 1/16 output
1/17800 sec. at M 1/32 output
1/32300 sec. at M 1/64 output
1/41600 sec. at M 1/128 output

So, as you can see, duration isn't equal to 1/32, it's about 1/16 of time of full power

Accordingly to your first question, I didn't find anything about power output in the manual but I don't have time now to check it crafully

rokkstar wrote:I was wondering what the output watts of an SB800 were. I mean, is it equivalent to a 100w lightbulb, or a 500w bulb etc?

Cheers

i have always wondered why flash are never quoted in watts, similiar to studio lights.

rokkstar wrote:So would the light from a 500w haligen builders light be as bright as that from an SB800?

Matt,

Very simply, no.

That said, those sorts of lights can be made to work quite well as studio lights.

Using a diffuser of some sort will be very helpful too; the direct light output from these will be quite harsh. Point them away from the subject, into a brolly, and allow the brolly to provide your diffused light source, or make up a softbox to provide the required diffusion.

And be careful of the heat these lights generate. At this time of year they'll replace your room heaters quite effectively, but you'll need to allow a satisfactory distance between the lights and any diffuser material to avoid having the diffusers set of your smoke detectors.

More importantly, consider the extra cost of your AC during the warmer months, when you'll be using it to counter the warmth these lights will generate.

As a final observation, if you're using them for still life type photos in, say, a light tent, they'll be perfect, all other issues considered.

And as a final, final observation, use a preset, custom white balance.

Hlop wrote:Correct me if I'm wrong but it should affect both - power and duration. Here is a table from SB800 manual:
1/1050 sec. at M 1/1 (full)
1/1100 sec. at M 1/2 output
1/2700 sec. at M 1/4 output
1/5900 sec. at M 1/8 output
1/10900 sec. at M 1/16 output
1/17800 sec. at M 1/32 output
1/32300 sec. at M 1/64 output
1/41600 sec. at M 1/128 output

Sorry to be stupid here, but what does that exactly mean?
With flash dialled down to 1/32 the time it fires for is 1/17800 of a second? That is incredibly fast. So does that mean that you get a very very very quick burst of light?
If someone could explain this to me as if I was 4 that would be of great help

gstark wrote:
And be careful of the heat these lights generate. At this time of year they'll replace your room heaters quite effectively, but you'll need to allow a satisfactory distance between the lights and any diffuser material to avoid having the diffusers set of your smoke detectors.

Learnt that the hard way Gary

rokkstar wrote:With flash dialled down to 1/32 the time it fires for is 1/17800 of a second? That is incredibly fast. So does that mean that you get a very very very quick burst of light?
If someone could explain this to me as if I was 4 that would be of great help

You don't need an explanation - you're absolutely right And at 1/128 of power it's just 1/41600 of second!

rokkstar wrote:With flash dialled down to 1/32 the time it fires for is 1/17800 of a second? That is incredibly fast. So does that mean that you get a very very very quick burst of light?

That's exactly what it means.

And yes, it is very fast; blink and you miss it. Literally.

The timing of that burst of light is, of course, critical too. Your shutter must be fully open for the total duration of that burst light. If your shutter is too slow to open, or too quick to close, then you won't get all of your image area (sensor) correctly exposed.

That's what the process of flash synch is all about.

rokkstar wrote:

gstark wrote:
And be careful of the heat these lights generate. At this time of year they'll replace your room heaters quite effectively, but you'll need to allow a satisfactory distance between the lights and any diffuser material to avoid having the diffusers set of your smoke detectors.

Learnt that the hard way Gary

Fortunately, no.

It's just common sense.

Thanks for all your help guys.

By jove I think I've finally got it.

Hlop
You are correct when you point out that the time changes as you reduce the output on the flash, but in real terms the reduced time has no effect on the image exposure. That is unless you are trying to freeze a moving bullet. Then again...the flash to subject distance would also have an effect on the speed of the flash as in increase in distance means the gun has to put out more light. I'll get back to you when I fully understand what I just wrote.