Definition of A Modeling Light, Modeling Light, Purpose, and Function

I think there needs to be some clarification of what a Modeling Light are, purpose, function, and how they manufacturer defines them. There are Modeling Lights that exist on both Hot Shoe Strobes, Studios Monoblock Strobes, and Pack Head Strobes.

I am quite aware there are differences of opinions of what some forum members personal views are in regard to what Modeling Lights.

While forum members are entitled to views their personal views and opinions, those views and opinions do not define a Modeling Light, the purpose of a Modeling Light, or the Function of the Modeling Light.

I moved a thread the other day where there was a question in regard to modeling lights the other day that a user who owned Alien Bees what attempting to use to shoot Video. The response from Alien Bees and a former post I personally started in regard to the Canon 600EX-RT Hot Shoe Flash having built in modeling lights being disputed as real modeling lights is why I am posting this thread for discussion now.

I hope that we can have a civil discussion that allows the clarification is what Modeling Lights are come out.

This is the response I copied that Paul C. Buff company responded with to the other post I moved to the Digital Video forum the other day when that poster contacted them directly today about using his Modeling Lights in his Studio Strobes for Continuous Light. They separate a continuous light from a modeling light and the purpose is defined as well.

"Keep in mind the AlienBees have a modeling light that you can keep on constantly, but this not a true, continuous light. The modeling light on the flash unit is used for previewing where the light is falling on your subject. The maximum wattage bulb the Alien Bee can accept is 150W. Most true continuous lights start around 300w"

The Falcon Eyes VL-100 is a great looking new LED modeling light, neatly designed to strap straight on to the head of a regular speedlite. Many people have talked about strapping a torch to the head of a flash unit, but this is the first purpose designed unit I have seen.

IS there a question i there?
A modeling light is a continuous light source -usually a tungsten bulb, a quartz-halogen bulb, or an LED - located in proximity to a flash tube. The purpose of a modeling light is to allow a photographer to visually a sense of the lighting effect the flash, when it fires, will create.
In my experience a light that isn't equal to the output of a 150 watt or better yet a 250 watt quartz-halogen bulb is basically worthless in most circumstances as it simply isn't bright enough for you to make a good judgement as to what the light is doing.
Most modeling lights now (and for the past couple of decades) have dimming controls. the intent of the dimmer is to emulate a lighting ratio but as I see it the flaw in that idea is that unless you are using identical light modifiers on each light and each light is also the same distance from the subject that unless you use a light meter to read the intensity of the model lamps brightness you can never accurately emulate the effect of the flashes.
One way to creatively use a modeling light is to use a long exposure time and let the output of the flash and the modeling light combine to lower the effective cumulative color temperature of the illumination i the photo.

A big misconception is that there is a parity between watts ( the modeling light) and watt-seconds ( the flash energy setting. At 1/125th second shutter speed you need approximately 2500 to 5000 watts to match the light the average 250 watt-second flash (at full power) produces. This is roughly a 3 to 5 stop difference  so if you drop your shutter speed to 1/4 to 1/2 second the 250 watt q-H modeling light and a 250 w-s flash is producing.

Ellis here is the rub.  Hot shoe strobes also have modeling lights that will never fit what you just described, yet they still have modeling lights as defined by their manufacturers.  Granted by your definition you would not considering them to be equal to what you are used to in the Studio.

We certainly understand stand there is a difference in Studio type Strobes and Hot Shoe type Strobes in terms of power.  Yet we can still agree even though they are different they are still both Strobes!   Same with Modeling Lights!  There may be a difference in Power of Modeling Lights between Strobes, and there is, yet they are still modeling lights.   As good example of this is an Alien Bee 400 comes with a weaker strength bulb for Modeling Light than and Einstein does from the same Manufacturer.  Each of the lights have Modeling Lights right from the factory but one is shipped with a much brighter light than the other.    Still they are both Modeling Lights.

Hot Shoe Strobes still have Modeling lights according to their manufacturer and what the definition of what the purpose of a modeling light is.

While they might not fit your definition of Brightness or Wattage ( which by the way is a measure of the power available at the bulb). Lumens is the Intensity of the Light when you look at the bulb at the source, and Lux is how bright the measured area is that is actually light up.  They still have modeling lights.

If we can agree that  the purpose of a Modeling Light is to give the photographer an idea how the light will actually fall on the subject prior to creating the photograph then that will be a big accomplishment.

I do not know where the idea came from that Modeling lights had to be continuous light came from because for more than 10 years now you could turn a modeling light on or off.  A modeling light could be dimmed.  Some Strobes did not have Modeling lights at all.   They would also track with the setting on the Strobe or Pack head depending what system you had or what setting you had it on or they would work independently.    They certainly did not have to be continuous light.

Years ago in the film days we were talking Poloroids to make sure our lights were set up right before shooting our film.  It sure beat wasting film and going through processing to find out.   Now we are in the digital age and we get instant feedback.

In hotshoe mount flashes the very low power light the marketing departments are not really modeling lights. It's marketing hype pure and simple. When was the last time you used that function to preview the lighting effect the flash will create? And if you did activate it, did it make you decide "hey the light will look better if I move over here?" If you have ever used that function to preview, I bet you didn't then decide to move the light's position or change the modifier or zoom the AoL (angle of light) on the flash. Or did you?

So to re-iterate: calling the brief little burst of light the marketing and sales force calls a hotshoe flash's modeling light is 99.5% empty hype, ..05% a bell, and 0.0000% whistle.

The reason I am so adamant about this is that it is not on long enough for you to see what you are doing! And it is also too weak by far to be useful if you are using any sort of light concentrator or diffuser.

Nionyn wrote:

Jason Stoller wrote:

Ellis here is the rub. Hot shoe strobes also have modeling lights that will never fit what you just described, yet they still have modeling lights as defined by their manufacturers.

See below.

Granted by your definition you would not considering them to be equal to what you are used to in the Studio.

OK, so they're not that good...

We certainly understand stand there is a difference in Studio type Strobes and Hot Shoe type Strobes in terms of power. Yet we can still agree even though they are different they are still both Strobes! Same with Modeling Lights! There may be a difference in Power of Modeling Lights between Strobes, and there is, yet they are still modeling lights. As good example of this is an Alien Bee 400 comes with a weaker strength bulb for Modeling Light than and Einstein does from the same Manufacturer. Each of the lights have Modeling Lights right from the factory but one is shipped with a much brighter light than the other. Still they are both Modeling Lights.

Hot Shoe Strobes still have Modeling lights according to their manufacturer and what the definition of what the purpose of a modeling light is.

Just because the manufacturers decided they'd call this feature "a modelling light" does not mean that it is in reality, or that it is a useful substitute for a real one.
It has some small usefulness but it is not a real or a particularly effective modelling light.
In reality it's just marketing cant designed to sell more hotshoe flashes.

As another example of this: some time ago some lens manufacturers decided that they would market some lenses capable of focusing closely as "macro" lenses.
The fact that these lenses could not produce a 1:1 image on the film or sensor (which would have made them actual Macro lenses) didn't deter them, naturally.
Once again, marketing cant designed purely to sell.

While they might not fit your definition of Brightness or Wattage ( which by the way is a measure of the power available at the bulb). Lumens is the Intensity of the Light when you look at the bulb at the source, and Lux is how bright the measured area is that is actually light up. They still have modeling lights.

If we can agree that the purpose of a Modeling Light is to give the photographer an idea how the light will actually fall on the subject prior to creating the photograph then that will be a big accomplishment.

That's why they're called "modelling" lights. Because they afford one the ability to see how the light models the subject.

The "modelling light" feature available in some hotshoe flashes can be useful for aiming the unit where you want it to light, and that's great - no problem there. But to suggest that they are good for actually seeing how the light from a hotshoe flash in a softbox (for example) will actually model the subject of a portrait (again, for example) really is a bit of a stretch.

I do not know where the idea came from that Modeling lights had to be continuous light came from because for more than 10 years now you could turn a modeling light on or off. A modeling light could be dimmed. Some Strobes did not have Modeling lights at all. They would also track with the setting on the Strobe or Pack head depending what system you had or what setting you had it on or they would work independently. They certainly did not have to be continuous light.

You seem to have a basic misunderstanding of the meaning of the term "continuous" in this context.

Tungsten, Tungsten-Halogen, HMI, CSI, Low and High pressure Sodium, fluorescent, and LED light sources are all "continuous" light sources (though older fluorescents and some others do flicker a bit, it's true).
The fact that you can switch them all off is irrelevant. They are all termed continuous light sources because they all emit light continuously while they are switched on.

Flashes and strobe light sources are not continuous light sources because they do not continuously emit light but, rather, only emit light in brief flashes or in bursts.

A T-H or LED modelling light on a monolight or on a head is a continuous light source.
The fact that you can turn them off (manually or automatically) or dim them is, again, irrelevant.

Years ago in the film days we were talking Poloroids to make sure our lights were set up right before shooting our film. It sure beat wasting film and going through processing to find out. Now we are in the digital age and we get instant feedback.

Sorry, but I don't see the relevance of the above paragraph.

Without going back through the whole post item for item, the purpose of the modeling light on a Hot Shoe Flash is to see where the light and or flash is going to fall on the subject prior to taking the photo.  The Modeling Light on a Hot Shoe Flash Will do this just fine.  It certainly is not marketing hype.  So do not knock it until you have tried it.  Take a model with you and ask him or her if they can tell when a Model Light fired from a Hot Shoe Strobe hitting his or her body.

I cannot help it if you don't understand the relevance of photographers taking Polaroids back in the film days before shooting our film.

Studio Strobe Modeling Lights serve the same purpose.  They allow the photographer to see how the light will fall on the subject.  They just work differently because they are not fired as a burst from the Strobe bulb.  Yet they serve the same function.

If they both serve the same function and purpose, then the only real difference we have is that one works better than the other because of the size design and operation.  That I do not dispute.

The Canon and other brands of Hot Shoe Flashes that have Modeling Lights still are real Modeling Lights. Just because Studio Strobe Modeling Lights are bigger and work Better does not invalidate them.

Thnk of it as a Ferrarii and a Volkswagen

Both are cars, but designed differently.

Nionyn wrote:

Jason Stoller wrote:

Nionyn wrote:

Jason Stoller wrote:

Ellis here is the rub. Hot shoe strobes also have modeling lights that will never fit what you just described, yet they still have modeling lights as defined by their manufacturers.

See below.

Granted by your definition you would not considering them to be equal to what you are used to in the Studio.

OK, so they're not that good...

We certainly understand stand there is a difference in Studio type Strobes and Hot Shoe type Strobes in terms of power. Yet we can still agree even though they are different they are still both Strobes! Same with Modeling Lights! There may be a difference in Power of Modeling Lights between Strobes, and there is, yet they are still modeling lights. As good example of this is an Alien Bee 400 comes with a weaker strength bulb for Modeling Light than and Einstein does from the same Manufacturer. Each of the lights have Modeling Lights right from the factory but one is shipped with a much brighter light than the other. Still they are both Modeling Lights.

Hot Shoe Strobes still have Modeling lights according to their manufacturer and what the definition of what the purpose of a modeling light is.

Just because the manufacturers decided they'd call this feature "a modelling light" does not mean that it is in reality, or that it is a useful substitute for a real one.
It has some small usefulness but it is not a real or a particularly effective modelling light.
In reality it's just marketing cant designed to sell more hotshoe flashes.

As another example of this: some time ago some lens manufacturers decided that they would market some lenses capable of focusing closely as "macro" lenses.
The fact that these lenses could not produce a 1:1 image on the film or sensor (which would have made them actual Macro lenses) didn't deter them, naturally.
Once again, marketing cant designed purely to sell.

While they might not fit your definition of Brightness or Wattage ( which by the way is a measure of the power available at the bulb). Lumens is the Intensity of the Light when you look at the bulb at the source, and Lux is how bright the measured area is that is actually light up. They still have modeling lights.

If we can agree that the purpose of a Modeling Light is to give the photographer an idea how the light will actually fall on the subject prior to creating the photograph then that will be a big accomplishment.

That's why they're called "modelling" lights. Because they afford one the ability to see how the light models the subject.

The "modelling light" feature available in some hotshoe flashes can be useful for aiming the unit where you want it to light, and that's great - no problem there. But to suggest that they are good for actually seeing how the light from a hotshoe flash in a softbox (for example) will actually model the subject of a portrait (again, for example) really is a bit of a stretch.

I do not know where the idea came from that Modeling lights had to be continuous light came from because for more than 10 years now you could turn a modeling light on or off. A modeling light could be dimmed. Some Strobes did not have Modeling lights at all. They would also track with the setting on the Strobe or Pack head depending what system you had or what setting you had it on or they would work independently. They certainly did not have to be continuous light.

You seem to have a basic misunderstanding of the meaning of the term "continuous" in this context.

Tungsten, Tungsten-Halogen, HMI, CSI, Low and High pressure Sodium, fluorescent, and LED light sources are all "continuous" light sources (though older fluorescents and some others do flicker a bit, it's true).
The fact that you can switch them all off is irrelevant. They are all termed continuous light sources because they all emit light continuously while they are switched on.

Flashes and strobe light sources are not continuous light sources because they do not continuously emit light but, rather, only emit light in brief flashes or in bursts.

A T-H or LED modelling light on a monolight or on a head is a continuous light source.
The fact that you can turn them off (manually or automatically) or dim them is, again, irrelevant.

Years ago in the film days we were talking Poloroids to make sure our lights were set up right before shooting our film. It sure beat wasting film and going through processing to find out. Now we are in the digital age and we get instant feedback.

Sorry, but I don't see the relevance of the above paragraph.

_________________________________

>> Jason Stoller wrote:

Without going back through the whole post item for item,

That's entirely the responder's prerogative, no worries - though you have missed some salient points in your response. {shrug}

the purpose of the modeling light on a Hot Shoe Flash is to see where the light and or flash is going to fall on the subject prior to taking the photo.

Yes, but that is not the same as modelling (as I explained above).

I guess you know something I don't. I know how the manufacturers describe it. From my experience I know the modeling bulb and flash tubes are two different animals and light is distributed slightly differently but the modeling bulb will give you an idea but not an exact one.

I should only have to type this once. This is a fact Canon 600EX-RT Hot shoe flash uses the same flash tube for the Modeling Light as is for the Flash itself. So you can actually see how the Light is going to fall on the Subject prior to taking the photo.

The Modeling Light on a Hot Shoe Flash Will do this just fine. It certainly is not marketing hype. So do not knock it until you have tried it. Take a model with you and ask him or her if they can tell when a Model Light fired from a Hot Shoe Strobe hitting his or her body.

Again, this is not the same as modelling (again, as explained above).

What I saw above is you defining terms or the word modeling and no source for your definition. I already know there are other requirements for a Modeling light to be effective and defined properly than just an armchair definition.

I cannot help it if you don't understand the relevance of photographers taking Polaroids back in the film days before shooting our film.

Maybe, but, as the person who made the point you are the best person to explain it to me

I absolutely understand the purpose and usefulness of shooting Polaroids, but I don't understand how shooting Polaroids relates to the current discussion of whether a short burst of intermittent flash light from a hotshoe flash classes as "modelling light" compared to the continuous modelling light from a monolight or pack & head system.

I would be grateful for your explanation.
I would appreciate it, and I might learn something from it.

Studio Strobe Modeling Lights serve the same purpose. They allow the photographer to see how the light will fall on the subject.

Do you mean how the light will model the subject or merely where it will go? There is a significant difference, obviously.

See above

They just work differently because they are not fired as a burst from the Strobe bulb. Yet they serve the same function.

See above.

See above yourself and read again

If they both serve the same function and purpose, then the only real difference we have is that one works better than the other because of the size design and operation. That I do not dispute.

As I (and others) have explained, they do not in fact "serve both the same function and purpose", despite the manufacturers choosing to misname them.

Manufacturers have not misnamed them. They are the Manufacturers LOL are they misnaming camera's camera's too just because you do not agree with their definition. Who are all these others (Plural) you are referring to? Also are you implying that a majority is always right just because they might outnumber a minority and yell louder. I do not think history will support you there.

The Canon and other brands of Hot Shoe Flashes that have Modeling Lights still are real Modeling Lights.

Despite being worthless for actual modelling?
OK...

You are entitled to your Opinion but be careful not to Brand Bash. Your definition might not be the same as everyone's definition.

"Jason S wrote the line below"

Just because Studio Strobe Modeling Lights are bigger and work Better does not invalidate them.

What you wrote is in quotes below because something got messed up as I was responding to you.

"Of course not. But they are not the same. Clearly."

Thnk of it as a Ferrarii and a Volkswagen

Both are cars, but designed differently.

What you wrote is in quotes below because something got messed up as I was responding to you.

"Oh, now we're really on to something! Unfortunately your analogy is invalid.
Nobody would claim that a VW was not a car, but you have not used terminology appropriate to your analogy.
If you were claiming that both were "sports" cars or that a VW was a "supercar", that might be an equivalent use of the example - and there would be a clear and obvious difference between the two.;-)"

I think you might be starting to get the point and I can leave this conversation here.  Yes you are correct they are both cars.  There are some differences in them but they are both cars. They both can be driven on the road.  One has more horsepower than the other and more options.  One is faster. Still they are both cars.  Whether they are in different classes and have different designs is irrelevant. Bottom line is they are still both cars.

I've been over this discussion with Jason before and we finally agreed to disagree.

There should be no argument about what a continuous light is.

A continuous light is one that is on continuously.

The only common photographic light that is continuous is an incandescent light, and they dim and brighten slightly in sync with the line frequency unless they are battery powered like a flashlight (torch for the Brits). I don't know but I suspect HMI lights are also continuous.

Fluorescent lights, LEDs, and the "modeling lights" of hot-shoe flash units are pseudo continuous lights. They all flicker on and off so fast that the persistence of vision makes them appear continuous. The same is true of movie projectors and TV sets.

When I tested the "modeling light" of my Nissin Di866 Pro the burst of light lasted less than a second, hardly enough for me to use it the way I use the modeling lights of my studio strobes.

One way I use a modeling light is to show me where the highlights and shadows are on a face. You might get some idea of this with a hot-shoe flash "modeling light", but what you can see is no where nearly as detailed as I can see with the modeling lights of my studio strobes.

I don't just look for a catchlight, I raise and lower the light looking for the eyes to "pop". I am looking for the light position where the colors of the irises suddenly brighten (i.e. pop) as I move the light. You simply can't do that with a hot-shoe modeling light.

Here is my opinion:

Do hot-shoe flash units have modeling lights? Well, according to the manufactures, yes. According to how I use a modeling light, no.

Can a hot-shoe flash modeling light be useful? Yes, in a very limited way.

The best use I can think of for a hot-shoe modeling light is seeing if the hot-shoe flash, especially if it is gridded, is properly aimed when used as a hair or accent light.

Since I would have to go through a change in the menu settings of my flash to get the modeling light then through them again to get back to the proper photographic settings I would rather just place my eye where I want the light to hit and look back at the flash - that is all that is needed to see if the flash is properly aimed.

Sailor Blue wrote:

I've been over this discussion with Jason before and we finally agreed to disagree.

There should be no argument about what a continuous light is.

A continuous light is one that is on continuously.

The only common photographic light that is continuous is an incandescent light, and they dim and brighten slightly in sync with the line frequency unless they are battery powered like a flashlight (torch for the Brits). I don't know but I suspect HMI lights are also continuous.

Fluorescent lights, LEDs, and the "modeling lights" of hot-shoe flash units are pseudo continuous lights. They all flicker on and off so fast that the persistence of vision makes them appear continuous. The same is true of movie projectors and TV sets.

When I tested the "modeling light" of my Nissin Di866 Pro the burst of light lasted less than a second, hardly enough for me to use it the way I use the modeling lights of my studio strobes.

One way I use a modeling light is to show me where the highlights and shadows are on a face. You might get some idea of this with a hot-shoe flash "modeling light", but what you can see is no where nearly as detailed as I can see with the modeling lights of my studio strobes.

I don't just look for a catchlight, I raise and lower the light looking for the eyes to "pop". I am looking for the light position where the colors of the irises suddenly brighten (i.e. pop) as I move the light. You simply can't do that with a hot-shoe modeling light.

Here is my opinion:

Do hot-shoe flash units have modeling lights? Well, according to the manufactures, yes. According to how I use a modeling light, no.

Can a hot-shoe flash modeling light be useful? Yes, in a very limited way.

The best use I can think of for a hot-shoe modeling light is seeing if the hot-shoe flash, especially if it is gridded, is properly aimed when used as a hair or accent light.

Since I would have to go through a change in the menu settings of my flash to get the modeling light then through them again to get back to the proper photographic settings I would rather just place my eye where I want the light to hit and look back at the flash - that is all that is needed to see if the flash is properly aimed.

Sailor Blue,

I find you slipping into the use of "hot shoe modeling light" distressing because you are so knowledgeable and respected. I see it as the first step toward watering down the meaning of modeling light. Meaning comes from usage in a community, not any particular person or entity defining it. Usage of "modeling light" in the industry is about being able to see how shadows and light fall on your subject when using one or more strobes, prior to taking the shot. Hot-shoe flashes can't currently let you do this. The way language works isn't about how the manufacturer or any single person uses a word or phrase. It's about how the community uses a word or phrase. Therefore, currently, hot-shoe flashes don't have modeling lights. If marketing departments can convince enough people in the photographic community to consider the short burst of light some hot-shoe speedlights provide to be a modeling light, then the meaning in the language will have changed. If this happens it won't be a "validation" of hot-shoe speedlights, it will mean that saying a flash has a modeling light tells you less about its capabilities.

Jason: Not wanting to call the short burst of light some hot-shoe flashes can provide a modeling light has nothing to do with validating or invalidating anything. It's about accurate communication. There should be another term for what these hot-shoe flashes can do. It's very valuable to see whether or not your flash is pointed in the right direction before you take a photograph. It's valuable, but not the same as what a modeling light does. Hot-shoe flash manufacturer's use the term "modeling light" to make their product seem to have the value of capabilities their product doesn't have. This is deliberate misuse of language.

John

johnblue3 wrote:

Ellis, nor have I ever done that based on the modeling lights in my Profoto 600R's.

The reason you and Ellis have never done that is because you are confusing what a Hot Shoe Modeling Light is Designed to do by its manufacturer and what it is able to do with what a Studio Strobe Modeling Light is Designed to do by its manufacture and what it is able to do.

As I did a mentioned down below in a response there is a difference in a Ferrari and a Volkswagen.  Yes there are differences in them and what you can do with each of them both the are both still real cars.  Would you like to argue that they aren't both really cars or that they aren't both real cars too?  Granted they are different.  I accept that, so is there any reason to repeat that point?

UKphotographers wrote:

An example of modelling light purpose and function..

Shooting actors in an army barracks last week at a garage facility amongst military equipment, I was sure glad of the 300 Watt modelling lights. Because the key light was only at 180Ws through 140x100 Wafers the sodium and fluorescent lighting in the depot caused no problem as I simply switched it off. Since the modelling lights shut off automatically when the flash fires these don't interfere with the flash lighting. This is something the sodium and fluorescent lighting can't do. This is also something the VL-100 and 600EX-RT can't do. Furthermore, shooting without modelling lights in this darkened environment would have made the subjects pupils dilate unnaturally.

I didn't choose the location, nor did I chose the studio site, this was determined by needing to be away from a film crew and sound engineers. All my flash units had working modelling lights, spare bulbs and spare fuses. A pretty white walled hall with a 12 foot ceiling, power supplies 10 feet away and air conditioning/heating would have been good, alas, this is the real world. You never know what may be required which is why you always stack the odds in your favour.

Ian what are saying may be true, but then again.....

Since the measurement in Watts is only the power available at the light, that does not mean much to me because its not the intensity of a light measured of the area that is its lighting up.  It is also not the intensity of the light measured at the light.  It is only power source available to it.

You also mentioned 12 foot ceilings so as the distance from the ceiling to the floor gets greater the Lux ( measured brightness of the area illuminated )  it actually is less than the Lumens or intensity of the light at the light or its bulb.  Since I was not present, all anyone has in this forum is your opinion of what you believe any flash was or was not capable of in the barracks of the garage facility you were in last week.   I have shot under Sodium lights and fluorescent lighting as well in the past.  I have done so during sports events and also when I was in the Military so I am very familiar with the lighting in Barracks, Garage Facilities, as well as in Air Craft Maintenance hangers.  This is why I am making the point that I am.

UKphotographers wrote:

Jason Stoller wrote:

johnblue3 wrote:

Ellis, nor have I ever done that based on the modeling lights in my Profoto 600R's.

The reason you and Ellis have never done that is because you are confusing what a Hot Shoe Modeling Light is Designed to do by its manufacturer and what it is able to do with what a Studio Strobe Modeling Light is Designed to do by its manufacture and what it is able to do.

Arguing that a piece of equipment has a function is one thing, but finding a use for the inadequacy of that function is another. Despite what the manufacturers want to call it the modelling light function you're talking about is just inadequate for the majority of situations. With its limited brightness and limited duration - what do the manufacturers say its "designed" to do?

Canon Has clearly stated in their manual on page 38:

When the camera's depth of field button is pressed, the flash fires continuously for 1 sec. This is called the modeling flash. It enables you to see the shadow effects on the subject, and the lighting balance during the wireless flash shooting (p 47, 75).

There is your answer from one Manufacturer Canon.

If you want it from a Strobe manufacturer I know Paul C Buff has one:

Modeling Lamps In order for the photographer to be able to visualize what the scene is going to look like when the picture is taken, studio flash units contain Modeling Lamps. These are incandescent lamps of modest power that are placed in the studio flash in such a position as to mimic the light that will be emitted by the flash when the actual picture is taken.

There are certain considerations that must be met if the photographer is to be able to rely on his modeling lamps to provide a What-You-See-Is-What-You-Get (“WYSIWYG”) preview of the actual shots.

Some manufacturers ignore the requirements for truly accurate modeling lamps. This can result in exposures that don’t look like what the photographer expected and the requirement of many test shots and adjustments in order to achieve a certain lighting effect.

Accurate WYSIWYG modeling dictates the following:

1. Modeling lamps must accurately track flashpower adjustments in order to provide a constant relationship of modeling Lumens to flash Lumenseconds, with errors no greater than 1/10 to 2/10f at any power setting.

2. Modeling lamps must project similar beam patterns to the flash.

3. Modeling lamps, like the flash, should be immune to variations in power line voltage in order to maintain consistent accuracy regardless of fluctuating power lines. In this regard, all Paul C. Buff, Inc. studio flash systems employ high-precision voltage regulation of both modeling lamps and flash to provide consistent output at all power line voltages from 105 to 135 Vac.

We are not aware of any other manufacturer that provides any voltage-regulation of modeling lamps whatsoever and are aware of several whose modeling lamps fail to track flashpower, with errors of up to 3/4 f-stop or more – far too much error for effective visualization

Below is Nikon's Definition for their Modeling Light Found on Page E-21 for the SB-910

1. When the test firing button is pressed, the flash fires repeatedly at a reduced flash output level. This is useful for checking the illumination and shadows cast on a subject before actually taking the picture.
2.  
   • Test firing and modeling illumination can be selected in the custom settings. (0B-17)
   • The flash fires as a modeling illuminator for up to approx. 1.5 seconds.
   • When the depth-of-field preview button on a camera compatible with modeling illumination is pressed, modeling illuminator fires even when the SB-910 is not set to modeling illumination. For details, see the camera user’s manual.

Pentax AF540FGZ Hot Shoe Flash Page 58

Modeling Flash/Test Flash

Before taking the picture, firing a modeling flash helps you to see how shadows are cast on the subject.