# No, Not Stupid question, But Question, Sir/ Madame



## surapon (Jan 21, 2015)

Dear Teachers and Friends.
Another question that I do not know and Want to know to compare and Make decision to buy light equipment in the near Future.
Yes, The question about Lighting, Sir/ Madame.
Why All Flashes are specify such as = Canon 580 EX = 58m./ 190' @ ISO 100 ( for the Flash Power, Canon 430 EX II=43M./ 141 ' @ ISO=100, Yes I am Understand that 430EXII is less power than 580EX.
BIG BUT, The Studio Light/ Flashes Such as Phottix Indra 500TTL power = 500 Watts Studio Strobe or 400 Full Power Flash---Yes, I complete understand of 500 Watts Power of Light.
BUT I do not know how to compare to Camera Flash 58m./ 190' @ ISO = 100----Yes? How many of 580 EX to be equal 500 Wats Power of Phottix Indra 500TTL ?

Well, Yes, I have so many Flashes in my hand, and Do not want to spend $ 1,200 US Dollars for Phottix Indra 500TTL, If I do not need to buy 10 of 580 EX II.
Thank you, Sir/ Madame.
Have a great Wednesday.
Surapon


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## IMG_0001 (Jan 22, 2015)

Dear Surapon, 

I think that the main problem is that the studio flash is meant to be used with modifier and the lit area is not going to be a given. Calculating an equivalent GN is therefore going to be a challenge as for a given power (the W or Js rating of studio strobes), the intensity of the light will change and the exposure would also vary accordingly. On the other hand, remembering that the GN is associated to a focal length for hotshoe flash, it implies a given area covered by the flash light.

That being said, I know that some studio flashes state a GN with a specified reflector angle, which can in turn be converted to equivalent focal length and compared to a hotshoe flash. I also recall reading that a 60m GN flash as Canon's 600ex-rt has about 60-70W capacitor energy, but this last statement should be verified.

I hope this helps.


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## IMG_0001 (Jan 22, 2015)

And as a side note, it is also important to remember that the flash power needs to be quadrupled in order to double its GN. 

*Typo edited...


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## Mt Spokane Photography (Jan 22, 2015)

Press 25, Light up the world. If that doesn't blind you, a Mazda 75 will.


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## WillThompson (Jan 22, 2015)

For a point of referance Canon 550EX, 580EX, 580EXII, & 600EXRT all output around 25 WATT SECONDS at full power. 

The main difference is the lens that focuses the light thus the differences in guide numbers.

No flash will output all the power stored in the capacitor since the arc stops when the voltage gets too liw


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## Lawliet (Jan 22, 2015)

surapon said:


> BUT I do not know how to compare to Camera Flash 58m./ 190' @ ISO = 100----Yes? How many of 580 EX to be equal 500 Wats Power of Phottix Indra 500TTL ?



The easiest way to compare lights would use the guide numbers you get when using the strobe with a specific reflector. For example Profotos Magnum reflector paired with the 500Ws B1 gives you a guide number of [email protected](studio lights are often rated at 2m or 6 ft, its more representative of real world useage - and the inverse square law doesn't work at such small distances when you use anything but a bare flash as it assumes a point source), or 90m. Which doesn't sound like much of a gain, thats because the reflector covers a wider area, but gives you a comparison for a set distance. (The narrow beam would have a gn of [email protected] or 180m, but I'm not aware of such a reflector for the Bowens mount while one of the Bowens tele-reflectors should perform in about the same ballpark as the Magnum). 

That changes when you use some sort of additional light shaping, the guide numbers become meaningless and only the energy counts. If you'd take a speedlight apart and look at the parts used you can calculate that they store somewhere from 40-80Ws, depending on the model. Add the longer recycle times and tendency to overheat and you have an idea how many flashguns you'd need in that case.


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## surapon (Jan 24, 2015)

Thousand Thanks to My Dear teachers and My dear Friends.
Now, I can understand the difference UNITS of Light per Camera Flash and Studio Flash/ Lights now.
Yes, As Hobby, I do not think I will need 2 of 500W Studio Light = $ 1,200X 2, US Dollars soon, Just Put 1, 2 or 3 Flashes on the 72 Inches Silver/ White Reflected Umbrellas, and That should be enough for Big Group Photos at the longer distant from Flashes.
Have a Great Weekend, Sir/ Madame.
Surapon


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## IMG_0001 (Jan 25, 2015)

surapon said:


> Thousand Thanks to My Dear teachers and My dear Friends.
> Now, I can understand the difference UNITS of Light per Camera Flash and Studio Flash/ Lights now.
> Yes, As Hobby, I do not think I will need 2 of 500W Studio Light = $ 1,200X 2, US Dollars soon, Just Put 1, 2 or 3 Flashes on the 72 Inches Silver/ White Reflected Umbrellas, and That should be enough for Big Group Photos at the longer distant from Flashes.
> Have a Great Weekend, Sir/ Madame.
> Surapon



Dear Surapon,

It is good to know that multiple lights even if set together in a single modifier, won't produce the same shadow as a single more powerful head. With multiple lights, you are likely to be able to see as many distinct shadows as thete are flashes. Sometimes it might look wrong and unnatural, sometimes its not a problem. This might not be that bad for large group photos, but might matter for headshots.


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## surapon (Jan 25, 2015)

IMG_0001 said:


> surapon said:
> 
> 
> > Thousand Thanks to My Dear teachers and My dear Friends.
> ...



Thanks you, Sir, Dear Mr. IMG_0001 .
Your Logic are Right on The Target About the Shadows of 2-3 flashes in one big umbrella., Yes, Sir, I will try and Report back to you, in next 2 -3 weeks.
Have a great Sunday.
Surapon


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