# Watt compared to guide numbers on speedlights?



## Quasimodo (Jan 22, 2013)

I have a set up in an improvised studio at work where I tried to blow out the background with a 600 and a 580, and using my other 580 as main light on the right side, and my 430 as the fill light. The main light and fill works great, but I have seen that the blow-out-the-background light works only so and so (they are both on full blast (+3). The problem is that they give only a semiblasted background, and the recharge time is slow, thus making me loose several shots. I have now borrowed a couple of Elinchrom sets at 200 watts per lamp, hence my intitial question at how does they translate from what I own myself?

Second, When testing the set up today I saw that it was way too bright/stronger than what I am used to with my canon speedlights.. but I think that I can reduce the power by changing aperture (I was shooting at ISO 165, Aperture 5,6, and 1/250 and this worked great for the sidelight and fill). I am thinking maybe in the vicinity of f11 now to get it equal? 

Thank you, 

G.

Maybe my question is not coherent here, but my problem is that I have never shot with strobes before, and I am used to my canon speedlights and their power..


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## neuroanatomist (Jan 22, 2013)

The short answer is that they don't translate. Guide number factors in distance and is affected by the zoom head on the flash (i.e. the 580 and 600 flashes have the same light output, but the GN of the 600 is rated higher because the head zooms to 200mm, while the 580's zoom only to 105mm. Watt-seconds ignores distance, and furthermore, the actual useful output of a monolight is determined by modifiers (e.g. the angular coverage of the reflector).

But, for comparison purposes, most estimates put the output of a 580EX II as equivalent to about 60-80 watt-seconds.


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## Quasimodo (Jan 22, 2013)

neuroanatomist said:


> The short answer is that they don't translate. Guide number factors in distance and is affected by the zoom head on the flash (i.e. the 580 and 600 flashes have the same light output, but the GN of the 600 is rated higher because the head zooms to 200mm, while the 580's zoom only to 105mm. Watt-seconds ignores distance, and furthermore, the actual useful output of a monolight is determined by modifiers (e.g. the angular coverage of the reflector).
> 
> But, for comparison purposes, most estimates put the output of a 580EX II as equivalent to about 60-80 watt-seconds.



Thank you Neuro. I shall never be easy should it...?

So basically, I am now with at least four times the strenght. They have a range of F stops from 1-5, so I will just try to put it as as little as possible and hope for the best  My back is killing me for carrying all the equipment back and forth (having no place to lock them in at work), so it would be great to be able not to carry the speedlights (the elinchrom is my workplace' property, thus stationary).


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## wickidwombat (Jan 23, 2013)

to blow out the background you need your background lights to be at least 2 stops over your key light
so you might be best off using your elinchroms to blow the background and the speedlights as the main lights

but you dont want your back lights too much over the top otherwise you will start getting light wrap which can look bad so basically you want some control. A light meter is an easy way to tweak all this when you are starting out but after not a very long period of time you just know what setting will get you in the ballpark and then its just fine tuning tweaks.

read this in detail and all will become clear
http://www.zarias.com/white-seamless-tutorial-part-1-gear-space/


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## Quasimodo (Jan 23, 2013)

wickidwombat said:


> to blow out the background you need your background lights to be at least 2 stops over your key light
> so you might be best off using your elinchroms to blow the background and the speedlights as the main lights
> 
> but you dont want your back lights too much over the top otherwise you will start getting light wrap which can look bad so basically you want some control. A light meter is an easy way to tweak all this when you are starting out but after not a very long period of time you just know what setting will get you in the ballpark and then its just fine tuning tweaks.
> ...



Thank you very much!

How do I shoot off the elinchrom AND the speedlights at the same time? I have an ST-E2 that I have used on my four speedlights (600 RT EX, 2x 580 EX II, and a 430 EX II). Now with the Elinchrom I have another remote control on top of camera to trigger the strobes. Can I use that to set off my flashes, or can I use the ST-E2, or the 600 RT EX (without actually shooting light from this) as a remote for both the elinchrom strobes and my non-radio canon speedlights? I am guessing that ST-E2 on top of my camera, and the remote trigger for the elinchrom in my hand shooting off the same time is too hard?


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## WillThompson (Jan 23, 2013)

If it helps all the Canon large speed lights 550/580/580II/600 max out at around 25 watt seconds of actual input power based on internal voltage & capacitor storage value.

Will T.


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## wickidwombat (Jan 23, 2013)

Quasimodo said:


> wickidwombat said:
> 
> 
> > to blow out the background you need your background lights to be at least 2 stops over your key light
> ...


the easiest way is to fire the speedlights with your st-e2 and enable the optical slave on the elinchrom units
check the manual for the heads you have but it should be the button with a picture of an eye then the elinchroms will detect the speedlights firing and fire themselves when they see the flash

forget the elinchrom trigger here unless you also have the expensive elinchrom recievers which can be plugged into your speedlights


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## Quasimodo (Jan 23, 2013)

wickidwombat said:


> Quasimodo said:
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> > wickidwombat said:
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Thanks Will T 

Wickidwombat.. I will go straight to the studio to check it out now. Thanks a lot for your advice  I will report if I manage this


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## kbmelb (Jan 23, 2013)

Quasimodo said:


> wickidwombat said:
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> > Quasimodo said:
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If you use the ST-E2 to fire your lights, you will find your studio heads won't be lighting your shot. The ST-E2 fires a E-TTL pre-flash and the studio lights will fire on that. Its a funny thing, you see them fire but they fire early and don't recharge fast enough to fire on the actually trigger light.

The only way to disable this is to put a piece of gaffer (or other) tape over the four smaller pin connectors on the hot shoe. Make sure not to cover the large one in the center.

There is a caveat to this, the ST-E2 will go to sleep after a few minutes and can't be woken by the camera since the pins responsible for non-firing communication are not connected. So if you don't shoot for a couple minutes you will have to switch the ST-E2 off and back on again.


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## Quasimodo (Jan 23, 2013)

kbmelb said:


> Quasimodo said:
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> > wickidwombat said:
> ...



Interesting! I just tried it, and it got way too dark, and what you mention might be the reason..

I was forced to go back to the four elinchrom strobes, and finally after putting the aperture to F16 I was able to both get the background well lit, and the subject ok (I am not Joe McNally, lol). However I am forced to use medium to wide angle since the studio is so small in depth, and I encountered a strange thing with my Sigma 35mm 1.4. A greenish colorcast in the middle of the frame. I tried to take of the filter to see if it helped, but it did not. I shot with my Canon 50mm 1.4, and it did not have a cast. I have shot many times with my Sigma with or without the speedlights, and it has worked fine. Worth to mention is that my camerabag was in my car for half an hour while dropping of the kids in kindergarten and driving to work, and it is a freezing minus 15 degrees celsius outside... Can that be it? I am enclosing two pictures of a coworker of mine that volunteered to model while I put up the lights..

The feedback of all of you is much appreciated!

G.


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## Quasimodo (Jan 23, 2013)

Sorry, a bit fast there. But notice the colorcast (greenish on her chin). Here is the canon shot.


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## Quasimodo (Jan 23, 2013)

needless to say, this is straight out of the camera, and no pp (except for cropping).


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