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Powerful LED strobe prototype on Kickstarter

 
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Davids



Joined: 31 Jan 2016
Posts: 180

PostPosted: Thu Aug 31, 2017 4:06 pm    Post subject: Powerful LED strobe prototype on Kickstarter Reply with quote

Stumbled upon a newly developed LED strobe that is purported to very powerful but in a relatively small package. They don't give information on the light temp, fluctuation in color output or other information that I'd be most interested in. But still, it's intriguing.

https://www.kickstarter.com/projects/photonicz/photonicz-one-the-worlds-first-weather-sealed-led#
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Pau
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Joined: 20 Jan 2010
Posts: 4841
Location: Valencia, Spain

PostPosted: Fri Sep 01, 2017 12:31 am    Post subject: Reply with quote

Wow!, maybe too good to be true?

No color temperature disclosed but they say
Quote:
With a light color rendering index of 95+

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enricosavazzi



Joined: 21 Nov 2009
Posts: 1205
Location: Borgholm, Sweden

PostPosted: Fri Sep 01, 2017 4:41 am    Post subject: Reply with quote

The claim "can deliver thousands of full power flashes (equivalent to more than 2,500Ws under various conditions) on a single charge" (copy-pasted from their web site) seems both a tall claim and a bit fuzzy to me.

W/s is normally used as a power rating for studio strobes (and frequently stretched and abused by manufacturers of cheap strobes). 1 Ws = 1 joule in terms of energy fed from the capacitors to the xenon tube. There are losses and several components warm up in addition to the tube, and the tube itself converts internally up to one-quarter of the power into NIR and UV (which does not contribute to illumination of the subject) in addition to the visible range. The xenon tube itself has a roughly 50% efficiency according to https://en.wikipedia.org/wiki/Flashtube . I don't know whether this includes only VIS, or also the UV and IR emissions. https://en.wikipedia.org/wiki/Luminous_efficacy lists a maximum of 22% luminous efficiency for white LEDs, i.e. significantly lower than a xenon tube, and the losses in the rest of the circuitry are probably similar to those in a xenon strobe. This would mean that a LED strobe would, at best, emit half the light of a xenon strobe when fed with the same Ws power.

One problem of building a high-power LED strobe is that the ratio between emitted light and input power in a LED is linear only within a given current range. Above this interval, pumping more power into a LED produces less than a comparable increase in emitted light. I suspect one may need literally a boatload of LEDs to produce the same emission at the same duration as a high-end xenon flash tube. It may be more realistic if the flash duration of the LEDs is increased to something like 50 ms instead of the 0.5-1 ms typical of a xenon tube.

If the specifications mean that one flash at full power in this LED unit is rated at 2,500 Ws (they may possibly be interpreted in different ways), and the rating is realistic, this makes the LED strobe very powerful, compared to most xenon-tube monoblocks. Even assuming that the rating is in "effective Ws" (a type of rating frequently used by strobe manufacturers, which in itself means objectively nothing) and the actual Ws output is one-third to one-half of the specified value (as common for "effective Ws" ratings), the actual power could be 800-1,200 Ws, still near the high-end for xenon studio monoblock strobes. Battery-operated xenon strobes in this power range, equipped with external batteries much larger than the strobe itself, can at most be fired a couple of hundred times at full power on a battery charge. Therefore, I am a bit skeptic about these statements.

On the other hand, it costs nothing to sit and wait for this LED strobe to come out on the market. I would be very happy to be proved wrong, because this would mean a whole new game in flash illumination.
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mawyatt



Joined: 22 Aug 2013
Posts: 2185
Location: Clearwater

PostPosted: Fri Sep 01, 2017 5:26 am    Post subject: Reply with quote

Most of the Xenon strobes I've used/disassembeled seem to rate them at the energy storage of the capacitor (1/2 CV^2).

The "rating" for the LED they use may simply be the sum of all the LED flashes, thus 1000 full flash outputs of 2500WS "total" equivalent power may just be 1000 2.5WS flashes.

I doubt a single LED flash output burst at 2500WS will be case.

Best,

Mike
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enricosavazzi



Joined: 21 Nov 2009
Posts: 1205
Location: Borgholm, Sweden

PostPosted: Fri Sep 01, 2017 11:13 am    Post subject: Reply with quote

mawyatt wrote:
...
The "rating" for the LED they use may simply be the sum of all the LED flashes, thus 1000 full flash outputs of 2500WS "total" equivalent power may just be 1000 2.5WS flashes.
...

I considered this interpretation as well, but decided to exclude it from the discussion in my earlier post because it would make the LED strobe so puny that it would have no practical use as a studio strobe. But it might turn out to be the correct one.
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