AlienBee and Effective W?S

OK there is a billion posts about what effective vs true w/s are. But I have not seen anyone actually do a test and see if there is any advantage in converting energy in to light in some strobes. So I did it myself:

I took brand new AlienBee 1600 (true 640w/s ~ $350) and generic eBay strobe (300w/s ~ $100). Using my Sekonic L-308 I did the test. First I made sure that f-stops drop accurately in AlienBee and 1/2 power corresponds to exactly 320w/s if the full power is 640w/s. AB was remarkably accurate, and I was very impressed by that (I do not get that with ebay strobes).

Then I remote fired AB at 320w/s and eBay one at full 300w/s, both with a standard similar size reflector. Took a reading with Sekonic at the same spot. Both read f/8.

So it does not seem like there is any validity to the effective w/s, and even the cheapest strobes have about the same conversion efficiency.

Finally, AB I think are very good quality, light strobes and I am by no means discouraged from getting AB's in the future, but effective w/s is not the reason to get them.

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Eugene

I am not totally sure if this sounds like an accurate comparison. Wouldn't it have been better if compared to something that actually has a true wattage more comparable to the stated effective watts. Something like what is offered int this bowens? http://www.bhphotovideo.com/c/product/220959-REG/Bowens_BW2088_Esprit_II_1500_Monolight.html

Actually it would not be. AB does not claim that effective w/s are the same as true w/s of any other strobe. They are claiming that there are different levels of efficiency and also I believe the compare to the ones without reflector. But if the crappiest strobes are just as powerful this probably invalidates effective w/s theory.
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Eugene

Well I don't claim to understand effective vs actual or the efficiency of claims of any strobe. But I just do not see how turning down a 640 watt strobe to match the output of a 300 watt strobe validates or invalidates any claims. Only seems that you proved that one strobe can be dialed down.

Maybe if you could explain it a little bit simpler for some one like me who is still struggling with this lighting concept.

One problem is that it's pretty easy to design the reflector to focus light more sharply and appear more powerful. Did you measure actual beam spread to be sure both were equal at equal distances?

By the way, have you read the definition of "effective watt seconds" presented on the alienbees web site? It already tells you what you attempted to test.

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RDKirk
'TANSTAAFL: The only unbreakable rule in photography.'

Yes I did, which part of it are you referring to? As far as spread, not I did not measure the spread, but as I said the diameter looks about the same. So I do not think this would be a big problem.
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Eugene

I am not sure whether you are just being argumentative or you are actually would like a more detailed explanation. I assume that you do:

1 f-stop means that amount of light is halfed, w/s are linearly proportional to the amount of light. So first I measure that halfing power in the back is actually 1/2 or 1 f-stop less output. I did this first. So now I know that amount of light at 640w/s will be 2 times the same as what is produced at 320w/s. 320 ~ 300 are already very close. so now I have to strobes that have true 320w/s and 300w/s. One claims that it uses some very efficient way to convert power into light, the other is bottom of the barrel and hence logical to assume that it uses the least efficient way to convert the light. We fire them both and get that the amount of light is the same. This means that effective output of AB at 640w/s will be the same as 600w/s with the cheapest light you can find on the ebay. So if there is difference between true and effective this is due to the fact that reflector is off (as far as I remember this is how they define it) not some conversion difference. Is that better?
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Eugene

Simple as that.

Nothing more nothing less.

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Regards
Paul L.

Depending on the angle of the reflector, the curve (if any), and the position of the lamp within it, an equalvalent diameter doesn't mean anything.

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RDKirk
'TANSTAAFL: The only unbreakable rule in photography.'

They were not the first to use the term, but I think they are the only manufacturer left using it.

Personally I think they should eliminate the term from their marketing material, at this point in the market it only damages them.

But hey, what do I know?

chekist said:

AB
was remarkably accurate, and I was very impressed by that (I do not
get that with ebay strobes).

Click to expand...

You are referring to the printed scales of the el cheapos, aren't you? Well, they are in no way exact. Better to wipe them off and do your own markings with an OH pen (i.e. calibrate the scale) by using your meter. Just a small hint.

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cheers, Peter

Germany

A lot of misinformation here.

To compare the actual flash power of units you cannot rely on the "standard" reflectors - they vary widely in beamwdth so this will tell you nothing - different reflector angles will yield up to 2f of error in comparative readings. AB and WL reflectors arey very wide (80°) and spread the light over a larger area than most - which are typically 35 - 50°. This will result in a false high reading from a narrow reflector over a wide one.

The best comparison is either to put them both in a double diffused soft box, or to use reflectors as similar as possible in beamwidth, or bare bulb if possible and point both lights toward one wall and put the flashmeter behind them pointing backward toward the opposite wall. This gives you a double bounce and eliminates to a large degree the differences in beamwidth.

The cheapo lights vary widely in efficiency - from nearly the same as AB to 50% less light per WS. No light I have ever seen is more efficient than AB by more than 1/10f. Many high end lights I have tested are about 30% less efficient - and I test with extreme accuracy.

There are always AB haters on these forums and yes, there is validity in the effective WS statement (as long as it is qualified as carefully as we do on out websites.). Contrary to the haters, we do not use this as our suggested basis of comparision. We suggest using WS and actual output with actual modifiers.

Paul Buff

paulbuff said:

There are always AB haters on these forums

Click to expand...

I wouldn't go that far....kvetchers and naggers - of course...but HATERS?

A German saying goes " why should it bother the moon that dogs are barking at him"...

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cheers, Peter

Germany

I agree with the previous point, but I would go further: Why is this "hating"? I think in my post I was very clear about what and why I am doing the test... You may disagree with my methodology, but having spend money on your product, I prefer not to be branded as an enemy some sort, especially since I am endorsing AB's in the same post...
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Eugene

Peter Berressem said:

paulbuff said:

There are always AB haters on these forums

Click to expand...

I wouldn't go that far....kvetchers and naggers - of course...but
HATERS?
A German saying goes " why should it bother the moon that dogs are
barking at him"...

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cheers, Peter

Germany

Click to expand...

OK, I'll go so far as to say there were no haters on this thread. Certainly not the initial poster. But on some of the other threads "haters" is appropriate. One said I was a **** and anti-semite and a few other things. But I suppose you are correct, let the dogs bark. But I feel compelled to address it when blatently false and malicious info shows up here. Which was not the case on this thread.

Paul Buff

Photogenic started the whole marketing nonsense about "effective watt-seconds" claim many years ago. The main problem besides the physical one Paul Buff lists (different reflectors,etc.0 is that Photogenic has never come clean about how the ydid their their tests or what lights they were comparing them too.

With regards to Paul C. Buff's companies (White Lightning and Alien Bees), my understanding is that they initially started using this marketing term term as their primary competitor back in the first few years was Photogenic.

Since Photogenic was pretty much unresponsive , some professional photographers (including myself) made the effort to put some pressure as consumers on Buff's companiesto start listing their true watt-second ratings. It took a couple of years but they finally clearly started listing true watt-second capacity.

Efficiencies between brands can vary mightily. Back in the late 1990s I made a series of tests for myself comaring my Norman P2000X system to Speedotron and then Elinchrom E1000 monolights and Balcars. I tested by using a Minolta Flash Meter IV --the meter was mounted o na light stand to keep a constant 8 foot distance between the head and the meter and all tests were done in the same studio. 10 readings were taken of each light and before these readings were made the strobe was plugged in for a half hour and fired several times to warm the flashtube up.

The tests were:

a.) each head as a barebulb (no reflector) source .

b.) Each head into a 48" Photoek umbrella

c.) each head in a Plume Wafer 100 softbox.

d.) with each brands standard reflector mounted , aiming the light into a V of two 4ft. x 8ft. white Fomecore panels.

One of the tests I ran was to get Flash Clinic or (the now defunct) Strobesmith company in New York to make me up an adapter cable that would allow me to use a Speedotron head on a Norman pack. The result was that in all cases the Norman head with a new flash tube by the way) was consistently 2/3rd to 1 stop less efficient than every other system I tested including the Norman pack + Speedotron head configuration.

I did not test any of the Paul C. Buff white Lightning gear. as the test predated the introduction of Alien Bees, they were not tested either, and Broncolor, Hensel and Profoto weren't tested because I couldn't get my hands on any at the time.

I have very skeptical about any manufacturers or their representatives claims until I test them myself. You should be too.

We have always listed true WS predominantly in in our ads and literature and have never used the effective wattsecond term without including the true WS rating and an explanation regarding the implications and meaning of the effective WS terms.

You are correct about variances in flashtube efficiency from one manufacture to another this is still true today, albeit it a lessor degree than when the term first appeared in Inverse Square Systems' Stroblox in 1984-85.

Photogenic continues to make "1250" units that are 500 true WS and "2500" units that are 1000WS.

Paul Buff