Strobe WS question

[JerryA]

Hi all, long time lurker and lighting newbie with a question. Is there a way to test a strobe to determine it's watt seconds?
I purchased an inexpensive set used and the person assured me they where 250WS output, but the company has 150WS units that look identical and the kit has all the same things in it.

I contacted the company and they did say there where some 250 WS kits that had been mislabeled. My photography career is a pipe dream ( I'll stick to shooting wildlife and birdies ) and I am selling these now, but realize I can't prove, and don't know how to prove to another buyer, that they are in fact 250WS. I was a bit naive to not have asked the original owner how he came to this conclusion and no owners manual or bill of sale came with them, so I'm starting to think I may have been scammed??

Any ideas on how to test them?? Thanks for any help

[vadim]

Do you have a lightmeter ? And what is the brand of the lights ?

[Ed Shapiro]

Hi Jerry-

It would help me answer your question if you named the equipment in question. I would also need the price you paid for the system in order to determine if you were scammed or not- you may have picked up a good deal for the equipment regardless of its power output or perhaps not- I gotta have this data to help you.

Is the unit a mono-light, a power pack unit with one or more heads wired to it or a portable unit intended for hand held use attached to the camera?

Watt/Seconds are electrical units of energy applied to the flash tube(s) of you unit at the time of the flash. A high voltage pulse enters the flash tube via its electrodes and ionizes the xenon gas within the tube causing it to create a burst of light. The watt/ second rating is determined by a mathematical formulia which takes into account the voltage and capacitance of the power supply abord the unit or contained in a separate power supply unit to which a flash head or heads are wired into via a power cable(s). Unless you know the actual electrical values of the voltage applied to the capacitors and the values of the capacitance there is no practical way of determining the actual watt/second rating without getting inside the unit with test equipment and/or reading the markings on the capacitors. This procedures must be done by a qualified technician who is fully aware of the high voltage circuitry involved in electronic flash technology. Either that or the manufacture should be able to know the power specifications of their own gear and label and advertise the units accurately and honestly. This "mislabeled" thing sounds kinda dodgy!

WARNING: Unless you are a qualified technician it is not advisable to pop the hood on any electronic flash equipment as they harbor leathel voltages that can cause serious injury or death. Also- DO NOT connect this unit to any digital camera untill you find out more about it. Some older or poorly made units may have excessive triger voltage, that is, the voltage that comes through the camera's synchronization system. If that voltage is too high, a protectice devise is required otherwise the excessive voltage can damage the electronics in you camera that is beyond repair.

Even of you knew the actual watt/second rating, believe it or not, the electrical energy is not the only determining factor in the practical and real effective power in terms of actual exposure. Theoretically and usually the difference in actual f/stop setting between a 100 w/s unit and a 250 w/s/ unit is about 1.5 stops. The other factors are the type of reflector is utilized in the business end of the unit- behind the flash tube and whether or not light modifiers are used in conjunction with the flash.

In mono lights or one piece had held portables, the electrical energy is applied to the flash tube via buss bars only inches from the capacitors where as units with external power packs may loose a bit of power in the long wires from the power supply to the flash head(s).

One test you can do is to take some flash meter readings where the light is 10 feet from the collector dome of an incident light meter- let me know the reading as ISO 100- and I can give you an educated guess as the the power outfit. This has to be raw light directly from the lamp head or moonlight flash tube.

It is also important to know the BCPS (Beam Candle Power Seconds ratting and/ or the ECPS rating (Effective Candle Power Ratings) in order to determine the real preformance of the flash equipment in terms of angle of coverage, issues of light fall off with wide angle lenses and other factors which help define the real effency of your flash gear under various working conditions and lighting configurations- see if there are any such specifications available from the manufacturer or importer of the equipment in question.

Don't be totally discouraged about flash usage just because you have possibly made a bad buy. Most flash units are useful for something and can play a part in a multiple lighting studio type set up. Lowe power units can give you shallow depth of field which is oftentimes handy in classical portraiture in order to do selective focus work or soften busy background by rendering them out of focus. They can be used as a background light, kickers and hair lights as well.

Come back with the info requested for more help.

Ed

[Songman45]

Ed is right (Ed is always right come to think of it), the Watt Second value is only one of many considerations. What that number generally tells me is, "Wow that's a powerful unit", or "Sounds kind of lightweight". The honest value to owning a peice of equipment is in its performance for you. If you got "taken" on the deal don't be too discouraged; its doubtless the first time nor the last for it to happen. Photographers are known for collecting equipment and you never know when something you got "stuck" with will one day be the exact item you want for a project.

If those flash units turn out to be underpowered for what you need as primary lights, the will work for something, as Ed said. I'm always interested in adding bits of gear to my stable so if you don't need an extra kicker or hair light in your bag let me know about taking them off your hands.

Steve

[JerryA]

Originally Posted by vadim

Do you have a lightmeter ? And what is the brand of the lights ?

Just sold it yesterday

Originally Posted by Ed Shapiro

Hi Jerry-

It would help me answer your question if you named the equipment in question. I would also need the price you paid for the system in order to determine if you were scammed or not- you may have picked up a good deal for the equipment regardless of its power output or perhaps not- I gotta have this data to help you.

Is the unit a mono-light, a power pack unit with one or more heads wired to it or a portable unit intended for hand held use attached to the camera?

Watt/Seconds are electrical units of energy applied to the flash tube(s) of you unit at the time of the flash. A high voltage pulse enters the flash tube via its electrodes and ionizes the xenon gas within the tube causing it to create a burst of light. The watt/ second rating is determined by a mathematical formulia which takes into account the voltage and capacitance of the power supply abord the unit or contained in a separate power supply unit to which a flash head or heads are wired into via a power cable(s). Unless you know the actual electrical values of the voltage applied to the capacitors and the values of the capacitance there is no practical way of determining the actual watt/second rating without getting inside the unit with test equipment and/or reading the markings on the capacitors. This procedures must be done by a qualified technician who is fully aware of the high voltage circuitry involved in electronic flash technology. Either that or the manufacture should be able to know the power specifications of their own gear and label and advertise the units accurately and honestly. This "mislabeled" thing sounds kinda dodgy!

WARNING: Unless you are a qualified technician it is not advisable to pop the hood on any electronic flash equipment as they harbor leathel voltages that can cause serious injury or death. Also- DO NOT connect this unit to any digital camera untill you find out more about it. Some older or poorly made units may have excessive triger voltage, that is, the voltage that comes through the camera's synchronization system. If that voltage is too high, a protectice devise is required otherwise the excessive voltage can damage the electronics in you camera that is beyond repair.

Even of you knew the actual watt/second rating, believe it or not, the electrical energy is not the only determining factor in the practical and real effective power in terms of actual exposure. Theoretically and usually the difference in actual f/stop setting between a 100 w/s unit and a 250 w/s/ unit is about 1.5 stops. The other factors are the type of reflector is utilized in the business end of the unit- behind the flash tube and whether or not light modifiers are used in conjunction with the flash.

In mono lights or one piece had held portables, the electrical energy is applied to the flash tube via buss bars only inches from the capacitors where as units with external power packs may loose a bit of power in the long wires from the power supply to the flash head(s).

One test you can do is to take some flash meter readings where the light is 10 feet from the collector dome of an incident light meter- let me know the reading as ISO 100- and I can give you an educated guess as the the power outfit. This has to be raw light directly from the lamp head or moonlight flash tube.

It is also important to know the BCPS (Beam Candle Power Seconds ratting and/ or the ECPS rating (Effective Candle Power Ratings) in order to determine the real preformance of the flash equipment in terms of angle of coverage, issues of light fall off with wide angle lenses and other factors which help define the real effency of your flash gear under various working conditions and lighting configurations- see if there are any such specifications available from the manufacturer or importer of the equipment in question.

Don't be totally discouraged about flash usage just because you have possibly made a bad buy. Most flash units are useful for something and can play a part in a multiple lighting studio type set up. Lowe power units can give you shallow depth of field which is oftentimes handy in classical portraiture in order to do selective focus work or soften busy background by rendering them out of focus. They can be used as a background light, kickers and hair lights as well.

Come back with the info requested for more help.

Ed

Hi Ed, wish I was closer to Ottawa, when I first joined Camel and got interseted in lighting and control, I read through this whole section and, of course read your many sagely written responses and thought provoking insights. Thank you, often we have no idea how far our influence roams, unseen!

Anywho, they are the Opus 150ws ( this is what is on the side of the strobes ) but the person ( yes, sounds doggy ) stated the output was actually 250ws, the problem is the 250ws Kit is labeled 250ws and the 150ws kit 150. I dloaded the owners manual, it's the same manual for both kits.

OPUS PRO - H Series Lighting Kits

I will contact the distributor again, and this is all about money and not wanting to dup someone, as I might have been. Can't help feeling stupid, but at 56, it ain't the first time LoL and in the big picture, pretty cheap!

I think I'd rather lose alittle money, but have a clear mind about it all.
Really appreciate your excellent and detailed response and you are right, these were just part of a "Bigger Plan" and, whether 250 or 150, would have had their uses.

Thanks again Ed

Originally Posted by Songman45

Ed is right (Ed is always right come to think of it), the Watt Second value is only one of many considerations. What that number generally tells me is, "Wow that's a powerful unit", or "Sounds kind of lightweight". The honest value to owning a peice of equipment is in its performance for you. If you got "taken" on the deal don't be too discouraged; its doubtless the first time nor the last for it to happen. Photographers are known for collecting equipment and you never know when something you got "stuck" with will one day be the exact item you want for a project.

If those flash units turn out to be underpowered for what you need as primary lights, the will work for something, as Ed said. I'm always interested in adding bits of gear to my stable so if you don't need an extra kicker or hair light in your bag let me know about taking them off your hands.

Steve

I agree Steve, Ed's is a store house of knowledge, experience and helpfulness.
Appreciated your input and your so right about being collectors of equipement LoL
I have come to the conclusion that this is part and parcel of the "Photographic Condition" Gear Lust

[vadim]

Originally Posted by JerryA

Just sold it yesterday
...

So the safe way to still somehow estimate the strobe power is direct it into a reflective umbrella putting it close to the umbrella surface so no light escapes.
Then take a picture of a grey card or similar object. Adjust the aperture till you get it in the middle of the histogram on your camera.

Now find someone with a 150 or 250 WS strobe and repeat. Needless to say that the distances should be equal. The reflected light from the wall also can have some effect. It is the best if you can do both tests in the same place. The accuracy of this method should be good enough to estimate if this is a 150 or 250 WS strobe.

Some lights are more efficient than others but if you determine that your strobe emits the same amount of light as some other 250W strobe then you can sleep tight.

[WayneF]

Originally Posted by JerryA

Anywho, they are the Opus 150ws ( this is what is on the side of the strobes ) but the person ( yes, sounds doggy ) stated the output was actually 250ws, the problem is the 250ws Kit is labeled 250ws and the 150ws kit 150. I dloaded the owners manual, it's the same manual for both kits.

OPUS PRO - H Series Lighting Kits

Watt seconds is an input power instead of an output power, and watt seconds cannot be measured directly from the light outside of the flash housing. There are a few factors involved.

However your link also gives Guide Number values:

OPL-H250
Flash Output 250ws
GN(ISO 100) 3M 113

OPL-H150
Flash Output 150ws
GN(ISO 100) 3M 83

Guide Number is (distance x aperture). These GN are given in meters, so Guide Number in feet would be 3.28 times these values (3.28 feet in one meter).

GN 113 meters = GN 371 feet
GN 83 meters = GN 272 feet

Guide number varies with the reflector, but they seem to specify these with the standard 55 degree reflector.

So using only direct flash with the bare reflector (no umbrellas, etc), taking a picture of a subject at exactly 20 feet from the full power flash, then:

GN 113 m = 371 feet would be correct exposure at GN 371/20 feet = f/18.5

GN 83 m = 272 feet would give correct exposure at GN 272/20 feet = f/13.6

These results could vary a little, we are at the mercy of the specifications, and they may be inflated a bit above actual, but you should be able to tell which one it was. Full power, ISO 100, 20 feet, f/16, and if it is slightly underexposed, it must be the 150 watt second model, and if not underexposed, it must be the 250 watt second model.

[JerryA]

Originally Posted by vadim

So the safe way to still somehow estimate the strobe power is direct it into a reflective umbrella putting it close to the umbrella surface so no light escapes.
Then take a picture of a grey card or similar object. Adjust the aperture till you get it in the middle of the histogram on your camera.

Now find someone with a 150 or 250 WS strobe and repeat. Needless to say that the distances should be equal. The reflected light from the wall also can have some effect. It is the best if you can do both tests in the same place. The accuracy of this method should be good enough to estimate if this is a 150 or 250 WS strobe.

Some lights are more efficient than others but if you determine that your strobe emits the same amount of light as some other 250W strobe then you can sleep tight.

Originally Posted by WayneF

Watt seconds is an input power instead of an output power, and watt seconds cannot be measured directly from the light outside of the flash housing. There are a few factors involved.

However your link also gives Guide Number values:

OPL-H250
Flash Output 250ws
GN(ISO 100) 3M 113

OPL-H150
Flash Output 150ws
GN(ISO 100) 3M 83

Guide Number is (distance x aperture). These GN are given in meters, so Guide Number in feet would be 3.28 times these values (3.28 feet in one meter).

GN 113 meters = GN 371 feet
GN 83 meters = GN 272 feet

Guide number varies with the reflector, but they seem to specify these with the standard 55 degree reflector.

So using only direct flash with the bare reflector (no umbrellas, etc), taking a picture of a subject at exactly 20 feet from the full power flash, then:

GN 113 m = 371 feet would be correct exposure at GN 371/20 feet = f/18.5

GN 83 m = 272 feet would give correct exposure at GN 272/20 feet = f/13.6

These results could vary a little, we are at the mercy of the specifications, and they may be inflated a bit above actual, but you should be able to tell which one it was. Full power, ISO 100, 20 feet, f/16, and if it is slightly underexposed, it must be the 150 watt second model, and if not underexposed, it must be the 250 watt second model.

Thank you both very much, at least this could effectively prove what they actually are!!! Thanks very much

I contacted the Company and they confirmed that this error did indeed occur and clients basically got the 250WS kit for the 150WS price, truth is there is only a 50.00 difference between the two, so my mind is at rest, considering what I'm selling them for!!

Thanks everyone for the speedy replies and help, my favorite forum to lurk and learn on Have posted some of my Raptor work over in the bird forum awhile ago and think I'll start taking a more active posting role. See ya all in and about