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Thread: LED flash?

  1. #1

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    LED flash?

    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. #2

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

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    benjiboy's Avatar
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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.
    Last edited by benjiboy; 04-09-2014 at 02:25 PM. Click to view previous post history.
    Ben

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    Mainecoonmaniac's Avatar
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    iPhone and other smart phones have them.
    "Photography, like surfing, is an infinite process, a constantly evolving exploration of life."
    Aaron Chang

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    fretlessdavis's Avatar
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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.
    New-ish convert to film.
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  6. #6
    benjiboy's Avatar
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    Quote Originally Posted by fretlessdavis View Post
    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.
    My LED light has a light output control that I can balance it with the ambient light for outdoor portraits in sunlight.
    Last edited by benjiboy; 04-09-2014 at 06:38 PM. Click to view previous post history.
    Ben

  7. #7
    fretlessdavis's Avatar
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    Quote Originally Posted by benjiboy View Post
    My LED light has a light output control that I can balance it with the ambient light for outdoor portraits in sunlight.
    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.
    New-ish convert to film.
    Pentax MX for 35mm
    Bronica ETRS for 645

  8. #8
    Dr Croubie's Avatar
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    Quote Originally Posted by fretlessdavis View Post
    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.
    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...
    An awful lot of electrons were terribly inconvenienced in the making of this post.

    f/64 and be there.

  9. #9
    benjiboy's Avatar
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    Quote Originally Posted by fretlessdavis View Post
    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.
    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.
    Ben

  10. #10
    fretlessdavis's Avatar
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    Quote Originally Posted by Dr Croubie View Post
    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...
    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.
    New-ish convert to film.
    Pentax MX for 35mm
    Bronica ETRS for 645

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