What strobe power for my simple one light setup ?

[MattKing]

Already with a/their standard reflector studio flash lights make different use of the capacitator energy (Wsec). So that value is only a rough guide.

I think AgX is trying to say something like what I was thinking - if you replace the reflector with an umbrella, those Guide Number ratings may not apply in the first place.
It is really, really hard to tell from published specs what sort of light you will end up getting from electronic flash equipment of the type the OP is considering.
If, however, you had one of the models being considered, and had measured the light output from that using the setup you are intending to use, those specs may allow you to estimate how much you will get from another similar model in the same line.
Of course, if someone on Photrio has experience with that line of flashes and that reflector, they could share that.

 

[AgX]

I think AgX is trying to say something like what I was thinking - if you replace the reflector with an umbrella, those Guide Number ratings may not apply in the first place.

Not what I wanted to say... though what you say is true nonetheless.

What I try to convey is that there still is a way between the electrical energy stored in the capacitator and the light actually leaving the flash. Already equipped with standard reflectors with same opening angle the output may vary at same energy level between models.

 

[Akzidenz]

great minds think alike ! I said the same thing
I certainly hope the op shoots a test or 2 … umbrellas and soft/ soft boxes gobble up light much more than reflectors or a bounce….. mnfgr specs should not really be trusted like gospel.. ( no shade to you Mr. Bill! )

@jnantz and @Chan Tran

Yes I’m also really sorry by this evolution, I would certainly prefer testing in a store the setup that I aim for. I will eventually test it at the delivery and send my results here.

 

[Chan Tran]

I have a Novatron 240Ws unit and an umbrella. I think it's barely good enough for f/8 at ISO100.

 

[Nokton48]

When I use monolights (Broncolor) in my studio portraiture I find I need 300ws at least with modifiers. Especially so with EI 50 Ilford PanF+ film which I prefer.

Better to have too much and dial it down than to not have enough

 

[wiltw]

Already with a/their standard reflector studio flash lights make different use of the capacitator energy (Wsec). So that value is only a rough guide.

^
Several decades ago, Chimera, the softbox manufacturer, published a test of many different brands of '1000 w-s' studio lights used in the same Chimera softbox. This clearly showed different outputs from 'the same' 1000 w-s pack+head

 

[removed account4]

^
Several decades ago, Chimera, the softbox manufacturer, published a test of many different brands of '1000 w-s' studio lights used in the same Chimera softbox. This clearly showed different outputs from 'the same' 1000 w-s pack+head

yup

 

[Pieter12]

Its kind of like film ISO. The manufacturer may use industry standards, but the resulting measured power output is dependent on so many factors, there can be quite a bit of variation.

 

[Mr Bill]

^
Several decades ago, Chimera, the softbox manufacturer, published a test of many different brands of '1000 w-s' studio lights used in the same Chimera softbox. This clearly showed different outputs from 'the same' 1000 w-s pack+head

Hi, I'm curious as to how much total variation, if you happen to recall, or perhaps have a copy of their test.

 

[wiltw]

Hi, I'm curious as to how much total variation, if you happen to recall, or perhaps have a copy of their test.

I do not recall individual results...too many to remember! But I, as a Dynalite owner, remembered seeing one manufacturer with higher power rating but lower output. Different combinations output more/less light and varied about 1EV in the amount of light ouput. I have tried searching the web for a copy of this test, but it occurred in the very early days of Internet data.

In doing a search one more time, I just found a 2008 test comparison of output for Professional Photographer magazine, in the middle of a very large high ceiling studio with all heads firing into the same Medium Chimera Pro softbox. Most brands 2400 w-s, but the Dynalite was 2000 w-s, and Zeus was 2500 w-s

https://www.dpreview.com/forums/post/27701036

• Broncolor Grafit A4 3200 (@ 2400 w/s) w/ Pulso 4 head: f/16.7
• Dyna-Lite M2000 w/2040 head: f/16.4
• Profoto Acute 2400 2R w/ Acute2/D4 head : f/11.9
• Profoto D4 w/ Acute2/D4 head: f/16.3
• Profoto 7A w/pro head : f/16.5
• Speedotron Blackline 2403 w/ 202VF head f/16.4
• Zeus 2500: f/16.5

0.8EV spread in this 2008 test.

 

[Mr Bill]

But I, as a Dynalite owner, remembered seeing one manufacturer (I forget if Speedotron or Norman) was -1EV in output compared to Dynalite.

Thanks for the update. I suspect that was something of a special case. I recall, on another forum, a particular pro photographer going on about the "efficiency" of Norman pack systems, after he did a series of his own tests. (I didn't bother to tell him he was using too small cables.)

Where I worked we were primarily a Norman/Photogenic house, with literally thousands of systems supporting our studio chain. (Although we did also look at just about every "pro level" brand at some point. I would see "pro level" as including the ability for ANY photographer to quickly swap out flash tubes, with no risk of receiving a shock from an exposed trigger wire.) Back in the 1980s or 90s (?) it was well-known, at least to us, that the standard extension cables weren't up to high power flash head, say 1,000 Ws and up. The HD cable should be used. So we typically used flash heads with a short stub cable, then a HD extension, as needed. (On occasion, if I needed to reduce flash power on a particular head for some sort of test, I would occasionally stick in an extra extension cable.) Anyway, I see that as something of an anomaly, a result of certain configurations.

Thanks again, I was just curious as to how much typical variation. I've seen a goodly amount of flash systems, just never bothered to compare on an "equalized" basis.

 

[AgX]

Its kind of like film ISO. The manufacturer may use industry standards, but the resulting measured power output is dependent on so many factors, there can be quite a bit of variation.

Is there a "measured power output"? They rather calculate their figures based on nominal capacitance and charging voltage.

 

[Chan Tran]

Is there a "measured power output"? They rather calculate their figures based on nominal capacitance and charging voltage.

But capacitance and charge voltage would be very close to power output in Ws but same power output in Ws won't neccessarily result in same amount of light nor same amount of light would result in same light intensity on the subject.

 

[removed account4]

im looking forward to the OP's pictures! proof is always in the pudding and his project sounds fun.

 

[wiltw]

But capacitance and charge voltage would be very close to power output in Ws but same power output in Ws won't neccessarily result in same amount of light nor same amount of light would result in same light intensity on the subject.

One of the issues with a pure comparison of electrical characteristis is that it does not compare the head

• surface characteristic of the reflect (white vs. chrome vs. satin metal
• angular coverage (e.g. 90 degree vs. 140 degree)

both have contribution to the conversion of electricity to brightness of output light, even assuming cable length and wire guage are equalized

That is why equalizing output via placement in same softbox gives a realistic assessment of light brightness.

While Mr Bill validly explains about cable selection and its effect upon output brightness, it is finessing what the average 'starting pro' might be buying from his retailer to open up shop..."I want a Brand Y with standard head and standard cable and their usual extension" (i.e. a 'pure stock' setup)
A comparison of 'pure stock' configuration from every manufacturer tells you what 'the standard stuff' would get (like comparison of cars with no special selection of brake pads and tires or shock absorbers.

 

[AgX]

The issue already starts at the mount of the tube.

 

[removed account4]

The issue already starts at the mount of the tube.

and flash meters can be wonky, especially if the operator doesn't know how to use them correctly ) as seen in other threads on this site where people might use a meter differently than a manufacturer might prescribed but seemly works fine... lots of chance of error in photography.

 

[Chan Tran]

and flash meters can be wonky, especially if the operator doesn't know how to use them correctly ) as seen in other threads on this site where people might use a meter differently than a manufacturer might prescribed but seemly works fine... lots of chance of error in photography.

flash meters work fine. They are not wonky.

 

[removed account4]

flash meters work fine. They are not wonky.

I've had minoltas that were doozy, 1 was was 2 stops off. tossed it, got a different one it was 1 stop off ... tossed it
got a 3rd one. it worked fine. sometimes they can be wonky... YMMV

 

[Chan Tran]

I've had minoltas that were doozy, 1 was was 2 stops off. tossed it, got a different one it was 1 stop off ... tossed it
got a 3rd one. it worked fine. sometimes they can be wonky... YMMV

I had 4 minoltas and they are within 1/10 stops of each other.

 

[removed account4]

I had 4 minoltas and they are within 1/10 stops of each other.

STOKED!
... mine must have been built on a Monday or Friday !

 

[M Carter]

Just a note on diffusion, umbrellas, etc. - I've seen plenty of cheap umbrellas that use some kind of thin nylon; they eat a half stop, but something looks "wrong" about the light, probably diffusion too thin. (And those things tend to fall apart quickly).

Often, it seems the thicker the diffusion, the nicer the quality of light, within reasonable bounds anyway. Or doing things like diffusing the reflector so the light is already softened a bit before it hits the main fabric.

And keep in mind, sometimes and umbrella is too small a diffusion source; it's not unusual to hang a 3' x 6' sheet of ripstop from a boom arm to get a nice big and soft look.

Someone mentioned ND gel for strobes; if the strobes or modeling light produce too much heat, aluminum window screen is a good alternative.