[Class A]

A new Kickstarter project promises a portable LED studio flash.

The project makes a number of hard to believe claims, the most unbelievable of them all being that there will also be a trigger for Pentax.

Kidding aside, the product advertising makes it look "too good to be true" and the Lighting Rumours article I linked to already provides some clarification, pulling the extraordinary claims about power output down from the stratosphere back to earth again.

Me pointing out that this product is planned to go into production should not be regarded as an endorsement on my behalf. As a matter of fact, I'm sceptical that it would be the right tool for me. My main concern is regarding colour fidelity. LED lights are known to have more or less spiky spectra and cheaper versions are entirely unsuitable for photography or video, as they have stark deficiencies regarding red tones.

A claimed CRI of 95+ sounds good, but even a high CRI is no guarantee for a decent rendering of all colours. I'd like to see the R9 (saturated red) value, or better a CRI(re), or TLCI score, or best, the spectrum itself. It does not matter if the light is plentiful and quick, if it does not work well together with today's
sensors to produce accurate colour.

The prototype does not appear to be quite capable of delivering all the promised specs. The BTS shots were taken in the shade with exposure
settings such that anything lit by the sun was blown out. Was this necessary to make the light from the LED strobe register at all? Also, why no use of
softboxes/umbrellas? A bare light source may sometimes be what one wants, but the portrait situations shown usually call for some (power
eating) modifiers.

Furthermore, I'm wondering how well that touch screen will work in the wet. If the strobe is supposed to be weather-resistant, the controls better be usable in bad weather.

Finally, comparing the size of the Photonicz head unit only with strobes that include a battery is not reputable, AFAIC.

I'll watch that space, but unless they can demonstrate that they can produce a useful spectrum and are able to produce useful levels of output, I won't even consider backing the project.

---

Last edited by Class A; 08-29-2017 at 04:55 AM.

[maltfalc]

going by the numbers in the article, they would have to be running that led at somewhere around 175,000 watts. the one in the prototype looks like a standard 200-500 watt led at best. 100% BS.

[Class A]

going by the numbers in the article, they would have to be running that led at somewhere around 175,000 watts. the one in the prototype looks like a standard 200-500 watt led at best. 100% BS.

They certainly don't showcase how powerful the prototype is supposed to be...

What do you reckon, is modern LED technology capable of in terms of colour fidelity?

White LEDs have a "blue" spike in the spectrum and while it might be possible to attenuate their output in such a manner that it becomes useful for photographic purposes it seems that this would have quite an impact on output levels.

Conversely, bold claims about fantastical levels of output power are probably not made with colour fidelity in mind (apart from appearing to be technically impossible to begin with, according to your estimation).

[mcgregni]

A claimed CRI of 95+ sounds good, but even a high CRI is no guarantee for a decent rendering of all colours. I'd like to see the R9 (saturated red) value, or better a CRI(re), or TLCI score, or best, the spectrum itself. It does not matter if the light is plentiful and quick, if it does not work well together with today's sensors to produce accurate colour.

So what White Balance preset should I use on my camera ....

[paulster]

I find it interesting that Alex dumped Pentax and moved to Phase because of the perceived colour inconsistency between lenses that made the 645Z unworkable for him, but an LED flash with a single chip can produce colour accurate enough to meet his standards.

I would have expected that they'd have to use a number of different chips combined to get a really good CRI without lots of spikes in the spectrum. It would be really interesting to see a spectral plot, or at least specific CRI index values (like the R15 skintone one that is critical for good reproduction).

I also hope that they'll have a frosted dome or some other means of getting this to work well with modifiers that are expecting omnidirectional light. Although that will further rob power.

[victormeldrew]

LED technology is progressing in leaps and bounds at the moment. It is entirely possible to get huge light output given enough amps and sufficient cooling...see the proliferation of LED headlights on cars and home lighting too. The biggest problem by far is heat, but that's nothing new for studio lighting. I do have my doubts though...the lighting output in that video was pretty unimpressive...and they are very vague on specs. But if it ever becomes a fully production product with good reviews, I'll happily have a look. I'm not tempted to gamble on it now though.

[rawr]

'The unit costs $749 for early-bird backers.'
'The optional $150 Photonicz Remote acts as a trigger and remote controller'.
So about USD $900 as a backer if you want a working kit.

Hard to get enthusiastic about this.

[KC0PET]

going by the numbers in the article, they would have to be running that led at somewhere around 175,000 watts. the one in the prototype looks like a standard 200-500 watt led at best. 100% BS.

I have been pondering trying something like this with LEDs. But there are a ton of variables and I have not had the time to work out all of the technical details not to mention making a prototype. But with some research I have done, I can see that even with some of the most efficient LED emitters out now, this power level may be down in the 80,000 watt range. That is of course not possible in a package size that small. To put that in perspective the 200 amp electric service panel in my house can deliver about 48,000 watts under a full load, so you would need a 400 amp electric service (at 240 volts) to deliver enough current. So even at 1/250 of a second getting that kind of power out of a small battery just defies the laws of physics. So they are using some funky math. The statement, “Because this is not a traditional strobe, it is not limited by the same technical restrictions of traditional strobes..." throws up a red flag, what exactly does that mean?

And I agree with Class A that the spectral quality is going to be the real issue for LEDs and particularly for portrait photography where we don't want people with strangely colored faces. I have been hopeful that a high CRI would produce some usable photo lighting but I think Class A has a good point that looking at the full output spectrum is going to be important for good photographic color rendering.

-------Edit-------

After thinking about this, I may have a clue into the way they are spinning this. In my calculations I am comparing a 700 WS strobe operating at 1/250 of a second to an LED device operating also at 1/250 of a second. If you assume that the strobe duration is shorter, then the power needed from the LED to achieve the same amount of light will be less. So if you say that the 700 WS strobe is using a duration of 1/10,000 of a second then the equivalent power needed from the LED at 1/250 of a second will be closer to 2000 watts. The problem with this comparison, though is that the 700 WS strobe at 1/10,000 of a second is only operating at a fraction of it's potential (maybe 1/16 or 1/32 power). Also I am also still thinking that a 2000 watt LED device and it's power source are still going to be rather large.

[maltfalc]

After thinking about this, I may have a clue into the way they are spinning this. In my calculations I am comparing a 700 WS strobe operating at 1/250 of a second to an LED device operating also at 1/250 of a second. If you assume that the strobe duration is shorter, then the power needed from the LED to achieve the same amount of light will be less. So if you say that the 700 WS strobe is using a duration of 1/10,000 of a second then the equivalent power needed from the LED at 1/250 of a second will be closer to 2000 watts. The problem with this comparison, though is that the 700 WS strobe at 1/10,000 of a second is only operating at a fraction of it's potential (maybe 1/16 or 1/32 power). Also I am also still thinking that a 2000 watt LED device and it's power source are still going to be rather large.

w/s is a measurement of total power used. flash duration makes no difference. the minimum an led needs to run at to reach 700w/s at 1/250 is 175,000 watts.

[KC0PET]

w/s is a measurement of total power used. flash duration makes no difference. the minimum an led needs to run at to reach 700w/s at 1/250 is 175,000 watts.

At the very basic level that is technically true if all you are doing is converting units. So yes 700 watt seconds/(1/250 second) equals 175,000 watts. However what I read in the referenced article is a comparison between a strobe based light and an LED based light (“At 1/250th of a second shutter speed on a full frame camera, PHOTONICZ ONE will output the equivalent of around 700Ws when compared to traditional strobes.”). I do not believe that watt-seconds for a strobe means the same thing as watt-seconds for an LED device. Watts is a unit of electrical power and not light output. LEDs and strobes have very different characteristics and efficiencies so a true comparison is fairly complex. Briefly you have to convert the light output of each device to a "constant lumen" output at a certain duration (say 1/250s) to get an apples to apples comparison. Any more explanation would be pages long so I will stop there.

Now to address the duration issue. Another thing that muddies the waters is that most of the flash units have a way to manually power them down, typically in 1/2, 1/4, 1/8 power and so on. This is for either reducing the light output to adjust exposure or to reduce the duration of the strobe pulse if you want to stop fast action. Basically to reduce the power the strobe duration is reduced, so if the full power of the strobe is based on 1/500s then 1/2 power will be 1/1000s, 1/4 power will be 1/2000s, etc. So what I am suggesting is that Photonicz is being tricky by saying that they compare to a "700 ws" strobe, but they are not telling you that that the 700 ws strobe has to be powered down to say 1/16 or 1/32 power to be comparable. I am suggesting that this is a lie of omission.

[maltfalc]

At the very basic level that is technically true if all you are doing is converting units. So yes 700 watt seconds/(1/250 second) equals 175,000 watts. However what I read in the referenced article is a comparison between a strobe based light and an LED based light (“At 1/250th of a second shutter speed on a full frame camera, PHOTONICZ ONE will output the equivalent of around 700Ws when compared to traditional strobes.”). I do not believe that watt-seconds for a strobe means the same thing as watt-seconds for an LED device. Watts is a unit of electrical power and not light output. LEDs and strobes have very different characteristics and efficiencies so a true comparison is fairly complex. Briefly you have to convert the light output of each device to a "constant lumen" output at a certain duration (say 1/250s) to get an apples to apples comparison. Any more explanation would be pages long so I will stop there.

Now to address the duration issue. Another thing that muddies the waters is that most of the flash units have a way to manually power them down, typically in 1/2, 1/4, 1/8 power and so on. This is for either reducing the light output to adjust exposure or to reduce the duration of the strobe pulse if you want to stop fast action. Basically to reduce the power the strobe duration is reduced, so if the full power of the strobe is based on 1/500s then 1/2 power will be 1/1000s, 1/4 power will be 1/2000s, etc. So what I am suggesting is that Photonicz is being tricky by saying that they compare to a "700 ws" strobe, but they are not telling you that that the 700 ws strobe has to be powered down to say 1/16 or 1/32 power to be comparable. I am suggesting that this is a lie of omission.

i know what a watt is, i know how efficient leds and strobes are and how to compare their output (total l/s output per pulse, not constant lumen output btw). i've been designing, building and repairing these things for years. given the relative efficiency of leds and strobes we're looking at somewhere over 100,000w at a minimum and possibly several hundred thousand watts given the reduced efficiency of leds when pulsed at high amps. and your entire second paragraph has absolutely nothing to back it up.

[stevebrot]

Watts is a unit of electrical power and not light output.

Watt = the SI unit for power (energy per unit time) and is only coincidentally associated with electricity.

Watt Second is a unit of energy and is equivalent to the joule. Watt second (ws) is the convenient unit for measuring flash output since power (Watts) then becomes directly proportional to duration.


Steve

[KC0PET]

Watt = the SI unit for power (energy per unit time) and is only coincidentally associated with electricity.

Watt Second is a unit of energy and is equivalent to the joule. Watt second (ws) is the convenient unit for measuring flash output since power (Watts) then becomes directly proportional to duration.

Steve

Yes I agree that the Watt is a unit of power and could be applied to anything that produces power. However in the common vernacular, watts normally refers to electrical power. Just as horsepower is typically used for motor output power. The reason for this is the way that these are measured and the tools that are used to make those measurements as well as common understanding of the meaning of the terms.

In my humble opinion and my best understanding, when we talk about watt seconds as applied to photoflash equipment, the "watts" part of the picture is referring to the power that is input to the strobe tube, not the light output itself. If I can be pointed to something that shows otherwise I am willing to listen. And yes I agree the ws is a convenient unit of measurement and particularly a good way to compare products as long as it is used consistently.

However and this is just me, I have long had an irritation with the photoflash industry for adopting the ws unit for modern strobe equipment. Some of the old flashbulb specifications used lumen seconds and I believe that is a more meaningful unit of measurement than watt seconds when we are talking about light output.

---------- Post added 08-31-17 at 12:26 AM ----------

i know what a watt is, i know how efficient leds and strobes are and how to compare their output (total l/s output per pulse, not constant lumen output btw). i've been designing, building and repairing these things for years.

My apologies I don't know you so I didn't mean to imply anything about your knowledge.

given the relative efficiency of leds and strobes we're looking at somewhere over 100,000w at a minimum and possibly several hundred thousand watts given the reduced efficiency of leds when pulsed at high amps.

And again I apologize if I didn't communicate well, I very much agree with what you are saying. What I am meaning to call into question is the claims of Photonicz and I was trying to draw a picture of why I think their claims are impossible.

and your entire second paragraph has absolutely nothing to back it up.

If you are referring to the first part of that paragraph, this is my best understanding of how the equipment works and how the manual power settings work on flash equipment (as well as my practical experience from using flash equipment). And again, if there is information that shows otherwise I am willing to listen (sorry I am from Missouri, you will have to show-me ) Some of the figures I picked are just examples to explain the math and my thought process, they may or may not apply to the Photonicz device. If you are referring to the latter part of that paragraph, that is just one possible way of many that Photonicz may be using to rationalizing their BS. No I have no way to back that up it is just conjecture. Or they may have just made that up for all I know. Am I overthinking it? Probably.

[maltfalc]

Yes I agree that the Watt is a unit of power and could be applied to anything that produces power. However in the common vernacular, watts normally refers to electrical power. Just as horsepower is typically used for motor output power. The reason for this is the way that these are measured and the tools that are used to make those measurements as well as common understanding of the meaning of the terms.

In my humble opinion and my best understanding, when we talk about watt seconds as applied to photoflash equipment, the "watts" part of the picture is referring to the power that is input to the strobe tube, not the light output itself. If I can be pointed to something that shows otherwise I am willing to listen. And yes I agree the ws is a convenient unit of measurement and particularly a good way to compare products as long as it is used consistently.

However and this is just me, I have long had an irritation with the photoflash industry for adopting the ws unit for modern strobe equipment. Some of the old flashbulb specifications used lumen seconds and I believe that is a more meaningful unit of measurement than watt seconds when we are talking about light output.

---------- Post added 08-31-17 at 12:26 AM ----------



My apologies I don't know you so I didn't mean to imply anything about your knowledge.



And again I apologize if I didn't communicate well, I very much agree with what you are saying. What I am meaning to call into question is the claims of Photonicz and I was trying to draw a picture of why I think their claims are impossible.



If you are referring to the first part of that paragraph, this is my best understanding of how the equipment works and how the manual power settings work on flash equipment (as well as my practical experience from using flash equipment). And again, if there is information that shows otherwise I am willing to listen (sorry I am from Missouri, you will have to show-me ) Some of the figures I picked are just examples to explain the math and my thought process, they may or may not apply to the Photonicz device. If you are referring to the latter part of that paragraph, that is just one possible way of many that Photonicz may be using to rationalizing their BS. No I have no way to back that up it is just conjecture. Or they may have just made that up for all I know. Am I overthinking it? Probably.

don't mind me, i'm kinda cranky tonight. :P this whole conversation has gotten way more pedantic than it needs to be. a rough ballpark estimate of the needed led wattage is all that's needed to prove photonicz's claims are false. their prototype would have to be literally hundreds of times larger to get anywhere near what they're claiming, especially air cooled. with that heatsink they're not gonna get much more than 100w averaged output, so even if they had a tiny magic led that could do 700w/s pulses at 1/250s, you'd still have to wait several seconds between shots just to avoid frying it. closest i've gotten is a design i need to get around to prototyping that will run at around 2000w continuously with a 3" 5-sided led cube, but even that's going to need to be tethered to a pretty massive water cooler.

[Class A]

@maltfalc
I don't think anyone has an issue with your posts.

I, for one, much appreciate your technical input.