Could someone clarify the power/light ratings of studio flash units? I have seen documentation that lists both effective watt/seconds and true/watt/seconds for a flash unit. What is the standard used to specify the flash power. If a manufacturer lists a flash as 300 ws without further definition, is that a true watt/seconds or effective watt/seconds?

How can the flashes from manufacture to manufacture be compared so there is a standard for defining light output capability?

Thanks
StanSC

Aloha StanSC!

(BTW, every time I see your signature, I wonder what your SC stands for...I know what my SPC II is...heheheh)

So, I'm most decidedly NOT a tech geek, but I sure do appreciate your question. I think the best way to compare lights is by the Guide Number. That seems to be more standard than the WS value given by different manufacturers. However, the WS output should be a fairly good comparison.

The Norman stobes I bought years ago included a whole lesson on how to judge light output, and it had to do with candle power. So many candle power = X WS, etc.

Bottom line...if you can, go to a distributor that handles several brands. Take your strobe meter, crank each strobe up to full, stand 10 feet away with your meter, and fire the strobe. Check your meter's reading and compare that way.

Of course, then there's the flash tube's light temperature.....

In my studio I use a Photogenic Powerlight 1250, which claims to put out 600WS on full. And I have a Norman Norlight 400, which claims 400WS as my fill. Then I have a variety of Photographer's Warehouse Powerlights claiming 110WS each that I use for hair, background and accent lights. I can get F8 out of the little 110WS lights through small softboxes, which is what I usually use to shoot portraits. And according to the CS Bridge, the temperature of these lights is 4400.

Hope this helps.
SPC II

Stan,

Thanks for the response on the lights and the information. Testing them side by side makes a lot of sense. I'll be checking out a few suppliers.

BTW - When I signed-up for this forum, I saw another Stan logged in - so I added the SC to tell us apart. It's stands for South Carolina.

StanSC

Aloha StanSC!

Allrighty then! Now I know. SPC are my initials, (Stan P Cox), and I'm the 2nd (II). Glad my suggestions and info helped!

Happy shooting!
SPC II

Andy Earl use only Canon Speelite when he is doing on locations shooting.
Check his website:

http://www.andyearl.com/

Best

Robert

I use only Nikon Speedlights on location when shooting outdoors. Even when shooting inside when I'm working with a single client. And I use 2 or 3 speedlights most of the time.

When setting up an indoor location for an event where lots of couples will be posing for a portrait, like military balls or school dances, I bring a backdrop and monolights with umbrellas.
SPC II
http://www.paramountphotography.com