GN vs. WS and which brand

[snokid]

Hi I'm looking at these three different brands 300-400 WS I think but not too sure yet. They are all ballpark the same price. How can I tell which one is better than another for my needs?

Norman
SP Studio Systems
Alien bees


Also is there such a thing to compare GN's?

I have been using off camera flashes and if I could tell how much light the strobes are compaired to those it would be easier to determine my needs for strobes.

Thanks
Bob

[Curtis N]

I can't answer all of your questions, but can provide a few insights. First be sure that you are comparing true watt-seconds, not the "effective watt-seconds" rating that AlienBees uses.

Comparing watt-second ratings is not a perfect method, but it's a better measurement of power than guide number. The GN depends heavily on the reflector attached, and becomes moot when you use it with a softbox or umbrella.

[snokid]

here's the spec for one of the normans, how can you tell if it's true WS?

thanks Bob

Specifications ML400/ML400R ML600/ML600R
Power 400 W-S
Recycle Time 1.9 seconds
Flash Duration 1/1200 second (full)
Power Control Full to -5f/stops
Modeling Lamp 150W (250W max)
Modeling Lamp Control Off, ratio and full
Sync Trigger Photo-eye, 1/4" sync jack
Optional Sync Trigger Built-in PocketWIzard™
Supply Voltage 105-125 VAC, 60HZ
Consumption 7A
Voltage Stabilization +/- 1%
Overload Protection 7A circuit breaker
Weight 4.88 pounds
Housing Dimension 5" x 5" x 6.5"
Flashtube Quartz, full envelope
Guide Number* 100 @ 10', ISO 100, bare bulb
Sync Voltage 6VDC

[Curtis N]

The watt-second ratings listed by light manufacturers usually describe the amount of power stored in the capacitor (true watt-seconds). "Effective" watt-seconds is a marketing gimmick that Alienbees uses. God only knows what it's based on. I'm not knocking them, since they do list the true watt-seconds in their specs, along with other information that goes beyond what other manufacturers provide.

[FlashZebra]

here's the spec for one of the normans, how can you tell if it's true WS?

thanks Bob

Specifications ML400/ML400R ML600/ML600R
Power 400 W-S
Recycle Time 1.9 seconds
Flash Duration 1/1200 second (full)
Power Control Full to -5f/stops
Modeling Lamp 150W (250W max)
Modeling Lamp Control Off, ratio and full
Sync Trigger Photo-eye, 1/4" sync jack
Optional Sync Trigger Built-in PocketWIzard™
Supply Voltage 105-125 VAC, 60HZ
Consumption 7A
Voltage Stabilization +/- 1%
Overload Protection 7A circuit breaker
Weight 4.88 pounds
Housing Dimension 5" x 5" x 6.5"
Flashtube Quartz, full envelope
Guide Number* 100 @ 10', ISO 100, bare bulb
Sync Voltage 6VDC
Norman has been manufacturing high quality flash gear for many years. It is very likely their Watt-second ratings are "true" ratings not some marketing hype gimmick (or if they are fudging the specs, it is likely they are doing so in a manner reasonably consistent with other well known flash manufactures). There is individual marketing hype, and somewhat coordinated marketing hype to contend with.

One interesting aspect of this particular flash unit, note that you can get an optional Pocket Wizard module built into the mono head (see link below).

I knew that this was an option on some Profoto brand flash gear (also very good flash gear), but I did not realize this possibility with Norman gear.

The SP Studio gear is a good is typically a goods value, but the flash heads are typically lower power and not quite as high quality gear as the Norman (or Alien Bee) (since you do not site a specific SP Studio unit, I am making this generalization which may not be precise). But, I also suspect the Norman gear is the most expensive.

See:
http://www.adorama.com/NMML400R.html?searchinfo=ml400R&item_no=1

Enjoy! Lon

[snokid]

Thanks Lon

Yes I saw the Norman unit with the PW, I would rather have it not built in. If it breaks then you have to send the whole thing back.

SP Studio Systems Excalibur SP-3200 is the unit I was looking at.

I'm leaning more towards the norman's I like the idea of their Norman Monolight Communication Software Kit for Windows.



I guess what is being said is that alienbees is the only one to watch out for goofy WS ratings?

it looks like most list
Guide Number 100 bare bulb, ISO 100 at 10 feet




this gives me an idea, the flashes I use from memory(i'm at work) are 84 GN bare bulb if you will, So if I mount them in a softbox then this flash would be about the same as the portable one I'm using now mounted in the same softbox? Somehow this doesn't seem right to me. Seems like a 400WS studio light should have more power than a portable flash. Am I missing something?

thanks again Bob

[FlashZebra]

Thanks Lon

Yes I saw the Norman unit with the PW, I would rather have it not built in. If it breaks then you have to send the whole thing back.

SP Studio Systems Excalibur SP-3200 is the unit I was looking at.

I'm leaning more towards the norman's I like the idea of their Norman Monolight Communication Software Kit for Windows.

I guess what is being said is that alienbees is the only one to watch out for goofy WS ratings?

it looks like most list
Guide Number 100 bare bulb, ISO 100 at 10 feet

this gives me an idea, the flashes I use from memory(i'm at work) are 84 GN bare bulb if you will, So if I mount them in a softbox then this flash would be about the same as the portable one I'm using now mounted in the same softbox? Somehow this doesn't seem right to me. Seems like a 400WS studio light should have more power than a portable flash. Am I missing something?

thanks again Bob
Remember that the Alien Bee units also give a "true" Ws rating in adition to the inflated one.

The Norman unit you cite is a nicer unit than the Sp Studio flash, but the SP Studio also looks reasonable, and it is a lot less expensive.

The Alien Bee unit is also less expensive, but still nice gear.

It is very unlikely you have any sort of guide number from a hotshoe based flash with a "bare bulb" (no reflector) guide number.

It is also very likely the Norman flash you seem most interested in has in the area of at least 3 to 4 times as much power as a Canon 580EX flash (possibly more).

With a 400Ws flash in a softbox, you should be able to get about F/8 at ISO 100 at 8 feet (or so). Please realize this estimate is just an educated ballpark guess, not a precise value.

Enjoy! Lon

[Curtis N]

the flashes I use from memory(i'm at work) are 84 GN bare bulb if you will, So if I mount them in a softbox then this flash would be about the same as the portable one I'm using now mounted in the same softbox? Somehow this doesn't seem right to me. Seems like a 400WS studio light should have more power than a portable flash. Am I missing something?Remember what I wrote earlier?The GN depends heavily on the reflector attached.The reflector and fresnel lens of a hotshoe flash unit concentrates the light in a narrow beam, which is quite useful for extending their distance range (guide number) when used without diffusion. Stick one of those things in a softbox, umbrella or other diffusion device and their weakness in comparison to studio strobes becomes apparent.

[snokid]

So I'm I just looking at it wrong? I should just figure out w f-stop/distance I would like to be able to use and work out how much power it will take to get it?

Bob

[Curtis N]

Most light manufacturers don't provide much information as far as f/stop & distance with various modifiers (AlienBees being a notable exception). There are a lot of variables.

What Lon and I are trying to explain is that the GN is dependent on the reflectors and other modifiers that direct the light. You can't compare the bare bulb GN of a studio light (measured with light going all directions) to the GN of a hotshoe flash (measured with the light reflected and focused in one direction). The GN is not a measurement of total light output, it's a measurement of how much light travels in one specific direction.

The best way to compare the power of studio strobes is to compare true watt-seconds. It's still not perfect, since some units are more efficient than others. But it will get you in the ballpark.