Pure white 5mm led's

I have a friend who is trying to build a camera light with a ring of 5mm leds, but he is having trouble finding ones without a blue tint. Has anyone built one of these before? And where is the best place to buy pure white 5mm leds?

All the cellphone cameras use Luxeon, maybe 5mm LED's are just not suitable for the job.

Have to define "pure white", there isn't such a thing with white phosphor LEDs. Basically he'll need to define a color temperature that he's happy with, and find a suitable LED to match (pure white, in the sunlight sense, is of course a blend of all colors (to some degree), a white LED puts out a specific frequency pattern (kind of a double-hump, one tall, one short, the tall being the "white phosphor" optimized frequencies, the other being the blue LED "base" emitting frequency leaking through), and will be lacking at one end or the other unlike the "flat" frequency of daylight.

Best bet would actually be multiple RGB LEDs arrayed and blended to create the whiteness desired, much more closely approximating sunlight, but tough to mix thoroughly to avoid "rainbow shadows" etc, especially in a portable unit.

The other problem is what is the application? I think most photography lights tend to start around 25 watt halogens at the bottom of the chart (really 35W+ seems "low"), and go up from there... to match that would take a LOT of LEDs (hundreds of 5mm, or maybe 10-20 or more of the new Crees, in a carefully shaped or diffused fixture), a "ring" of 5MM leds can't do it, period unless it's several feet around. If he wants just a flash, a few lux/cree units at high amps can probably do a decent job, but not for more than a few milliseconds at a time in any reasonable fixture.

Now if he wants a "micro-photography" light, that's reasonable, I'm no expert in tints but seems the Nichia CS is commonly said to be very "white" in color. It still won't be "daylight" white though, as described above.

Snow29 on left.
Always liked the smooth white beam of that LED. Less blue tint than any other 5mm led i've ever lit up. Anyone have any left from the group buy a year ago?

Despite being the whitest 5mm LED's I've seen, they are still slightly blueish. He'd have to set the camera's white balance to match that tint (or whatever other color temp he ends up with).

greenLED said:

Despite being the whitest 5mm LED's I've seen, they are still slightly blueish. He'd have to set the camera's white balance to match that tint (or whatever other color temp he ends up with).

Click to expand...

If it's a digital camera with automatic manual calibration (point the camera to a white sheet while being lit by the light source to be used and you push a button, so its "manual" in a sense you override the camera's automatic white balance, but its automatic, because the adjustment itself is just a push of a button)

For film camera its gonna be tough...

By the way, Peak LED Solutions will sell you Snow29's directly. I've ordered them twice in the recent past.

I have modded the following lights so far with them:
- Eternalight EliteMax
- Eveready Folding 4xAA Lantern
- TikkaPlus headlamp
- Black Diamond GIZMO headlamp
- LRI Proton (this was NOT easy . . .)

As you can tell, I just don't like the blue tint of Nichia's very much.

One benefit from a photography standpoint is that the beam tint of the Snow29 is very uniform. In comparison, the Nichia is blue in the center, and then shifts toward yellow as you move out towards the spillbeam.

That eternalight must look pretty all lit up with those snows.

You might try the BestHongKong UWLC Series pure white. The ones I purchased have a color temp in the 5000K area which is probably close to pure white with no tint in most people's eyes. They also seem to be more uniform in tint compared to other LEDs I've seen.

July 1 2007 - Re: Pure white 5mm led's

Old post hope we're still reading it. I 'll come back and check the replies
-

I have used many white leds for subject lighting when shooting closeups. I simply used
my manual white balance and I 'believe' that my photos are OK as far as color goes.

Since my application is not critical I often use whatever white thing I can find to use
to set my white balance. Illumiate it with the LED and shoot the white balance setting.
Then shoot the subject.

I look closely at all of my photos and they appear to be adequate. That is, they look
good, as good as anything else.

I work in spectroscopy. When using phosphers you are going to miss some colors
of light compared to an incandescent source. I've often wondered if that causes a
missing color in the final shot. Maybe someone who's got more spectrophotometric
experience than I can answer the question of 'missing colors' when using white LEDs.

Thanks.
Andre

PS. Christexan is right. For those who want to try a low wattage hanlogen bulb I
would say look at dealextreme.com as they have about 6 styles of 6 and 12 volt
halogen bulbs some as low as 5 watts. That might be useful for making a small
ring light.
========

Lumenation said:

I have a friend who is trying to build a camera light with a ring of 5mm leds, but he is having trouble finding ones without a blue tint. Has anyone built one of these before? And where is the best place to buy pure white 5mm leds?

Click to expand...

See this thread:

https://www.candlepowerforums.com/threads/149200

If he's quite serious about getting good quality LEDs and doesn't mind paying extra, I can hand-pick a matched set from my stash. PM me if interested.

Toshi

I work in spectroscopy. When using phosphers you are going to miss some colors
of light compared to an incandescent source. I've often wondered if that causes a
missing color in the final shot. Maybe someone who's got more spectrophotometric
experience than I can answer the question of 'missing colors' when using white LEDs.

Click to expand...

The main reason here is that LEDs are composed of blue, with a yellow-green phosphor that trails off in the orange part of the spectrum -- generally there is very little red output, even if the light itself looks perfectly "white" on a white wall. Almost all 5mm LEDs I've seen in this respect are quite bad, the best LEDs I've seen for color rendering are Cree WG and WH bins (the "warmest" of the cool white bins), those actually appear slightly greenish in many cases, but they tend to render subjects with more accurate color. I have not yet seen a 5mm LED come close to that, most are much more blue with less contribution from the phosphor.

When doing ceiling bounce tests, I find that turning on a separate red LED along with a white LED dramatically improves the way the room is rendered -- things like wood, or skin tones in pictures become much more vibrant. For 5mm LEDs, IMHO a good bet may be to mix in some white LEDs, with some red LEDs -- the trick will be to diffuse the light so that it evenly mixes. I suggest just playing around with some flashlights you already have (ie, if you have some red photons, and some white flashlights) and see what I mean for yourself.

I'm VERY interested in some of the white 5mm leds. I'll have to check back this afternoon.

Any updates?

I've played with many of the 5mm 'white' LEDs and with no mods, I feel the Snow 29s are the whitest. They are still blue compared to my two or three whitest Lux III LEDs, but compared to any other stock 5mm LED I've tried, the worst Snows are whiter than the best non-Snows.

Having said that, for outdoor color rendition, I think the best choice if you don't need much throw, is a Nichia CS C0 bin (the one that is blue in the middle surrounded with the greenish/yellowish spillbeam) sanded down with 1500 grit sandpaper. It ends up looking like a W0 bin to very slightly V0 bin. You definately lose throw, but for a realatively small area when it is really dark, the CS C0 sanded down is my favorite light for walking outdoors. Again, in VERY dark rural areas.

But in general, I think sanding any of the 5mm LEDs down improves the color rendition a bit. Many of them are splotchy before being sanded. Plus, I tend to prefer a wider hotspot even if it is a bit dimmer overall which the sanded LEDs almost always provide.