LED flash?

Discussion in 'Lighting' started by Chan Tran, Apr 9, 2014.

  1. Chan Tran

    Chan Tran Member

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    Does any manufacturer makes LED flash? I think today LED has high enough power to replace xenon flash in some application. It would be of long duration in fact the LED has to stay on a little bit longer than the actual exposure time. It can be used with any shutter speed of course at higher shutter there will less exposure. I think it should flash to save battery and also prevent it to get too hot.
     
  2. Paul Cunningham

    Paul Cunningham Subscriber

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    Manfrotto offers some continuous LED products that can also be used as flash units.
     
  3. benjiboy

    benjiboy Subscriber

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    I sometimes use a controllable output L.E.D light outdoors instead of fill in flash with a shoot through umbrella in a stand to fill the shadows, it's good because you can meter the light with a hand held meter to get the light balance right.

    P.S- I've never heard of L.E.D. flash but L.E.D. lights don't give out much heat , it's one of their advantages, however there are L.E.D. studio lights.
     
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  4. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    iPhone and other smart phones have them.
     
  5. fretlessdavis

    fretlessdavis Member

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    LED's an reach full power within a microsecond in the right applications, so the on/off delay wouldn't be an issue. However, the instantaneous output of a flash tube is much more powerful than a similar sized array of LEDs. It would take a fairly large array to get power equal to a flash tube.

    Also, high power short bursts of power would be quite difficult to properly drive an LED without damaging it... So it would require a much more complex power supply.

    Like benjoboy mentioned above, they'd be great for a continuous setup. They have a ton of advantages over incandescent hot lights. I don't know if anyone is making them, but an RGB array of LEDs could have built in dimming and light output, so it could be easily matched to ambient light for color balance.
     
  6. benjiboy

    benjiboy Subscriber

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    My LED light has a light output control that I can balance it with the ambient light for outdoor portraits in sunlight.
     
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  7. fretlessdavis

    fretlessdavis Member

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    I knew people were doing those, but it would be possible to make color adjustments with an RGB array-- that's what I'm not sure about. It would be nice to have a few presets on the LED controls to make adjustments, instead of needing gels.
     
  8. Dr Croubie

    Dr Croubie Member

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    That's actually something I started designing a year or two ago, specifically Macro-ring lights with adjustable colour from RGB LEDs. The prototype was just using 3 potentiometers to control the current to each colour in the LED plus 1 for overall brightness. I did have plans for an Arduino controlled version, even a screen or app-interface were (still are) all possible.

    Of course just being a single person competing against the likes of Chinese manufacturing, there's no way I'd end up getting a viable product to sell for any reasonable price, one day I might finish it for myself.

    The other major problem I found was with component variability and tolerances. No matter how good resistors and transistors I got, every LED behaved slightly differently. Turn the brightness pot all the way down, with RGB on full (so should be white), one LED goes just red, another LED goes just blue. Presumably this variability is also happening at full-brightness, just not as noticeable because of the intensity. To solve all this might need a whole lot of trimpots on each LED to calibrate each one to the others, and then costs go up exponentially.
    Also, to get any sort of real brightness (at least, that would overpower room lights at 5cm lens-subject distances), I couldn't get enough LEDs into the ring, the RGB LEDs that I had just can't compete with high-brightness single-colour ones.

    I came to the conclusion that to get anything 'properly calibrated' to a user-friendly version (ie, to a knob or switch that I could just set to a Kelvin Temp) would take more time (finding better components), resources, and equipment than I had access to, so it all sort of ended up in a drawer (it was also the time i got a real job, so that got rid of most of my free time).

    Not to discourage anyone else, or if it already exists I'd love to buy one too...
     
  9. benjiboy

    benjiboy Subscriber

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    My L.E.D. Light is balanced for 5,600 Kelvin daylight, and comes with an orange and blue filter, and it works for me.
     
  10. fretlessdavis

    fretlessdavis Member

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    Thanks for the info. I had figured it wouldn't be as simple as I thought!

    Also, that makes my future job a bit easier... I am in the process of designing a Graflarger type back out of a polarized LED light source using nothing but recycled pieces and off the shelf components... I was thinking of varying LED power to change contrast, but looks like that would be incredibly tricky.
     
  11. John Koehrer

    John Koehrer Subscriber

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    I didn't think intensity had anything to do with controlling contrast, just exposure.
    Using blue and green does. Doesn't it?

    Anyway back to the OP.

    There are quite a few LED ring lights available but I didn't see anything with power enough to use at a distance of more than a foot or three.
     
  12. fretlessdavis

    fretlessdavis Member

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    There are plenty of LED Hot Lights in B&H's video department. The problem is still size and power required for comparable output to a good strobe, though you do get the advantage of composing and metering with your lights.

    Also, I hadn't scoped these in a few months, but it actually looks like GISTEQ has LED panels that'll slip into a hot shoe on a camera that have adjustable color balance... There's one that's not too massive that's got 18w of output... so about equivalent to a 100w Halogen. That's a big increase over the LED ringlights and such, but for the same money, you can get much more power in a smaller size with traditional flashes, and probably get more usage before killing the batteries vs. the LED hot lights.