Walgreens is selliing little (about 8 cm long by 1.5 cm diameter)
clip on white light (they say) led flashlights for 2 for $5. Would a
half-dozen of these clipped to a ring around the lens work as a
serviceable ring light? No ancillary power supply would be needed.
Of course, you would have no control of the intensity except by
varying the number of lights. I have an led flash light that has
tremendous intensity and range. It's too big for this application,
but the batteries (three AAAs) have lasted for 1 1/2 years.
Another question. Could one photograph a white card illuminated by
led flashlights and get a rough idea of the spectrum by using the
computer's built in color analyzer? Photoshop will do the same thing.
Roger
On 27 Jun 2007, at 8:44 AM, karl shah-jenner wrote:
Hiya Kostas :)
: Θέμα: Re: Ring lights
| Now Karl I think you are a case of developing Flashaholism
| (being addicted to flashlight tech & paraphernalia.)
ah, it is true, though after accumulating an enourmous amount of flash
gear, I wanted something with continuous light, especially for
macro work.
| There is lot of issues regarding LED light, since it maybe
monochromatic but it is not always the same frequency from lot to lot
(called bin sorting). But that is a bit moot with digital macro.
Infact all
my lattest close up shots were made with a new genration AAA light of
greenish tint.
Most LED's have narrow wavelength emissions, but the white light
LED's use
a phosphor and emit quite a broad band of visible light.
Admittedly some
do exhibit 'tints', but I eliminate the off-colour ones and stick with
those that best replicate daylight (they rate at 4500K-10000K, I pick
around 6500-6700K).
| Luxeon LEDs are now outdated since the new bread is 100% more
effective.
| See Cree and Seoul Semiconductor offerings using the P4 die. And
begining this month it has been superseded by Luxeon Rebels
Rebels, Stars, K2's - whatever Luxeon LED model one uses, use the cool
white ones. I see the 3W Stars yeild 80 Lumens whereas the K2 6W
modules can produce 150 Lumen so it kinda depends what you want, and
whether they're priced right (and whether you can dissipate the
heat! :)
| Anyone that wants to make a led setup of his own, he is about
to dive
deep in converter circuits, heatsinking, wiring and current
calculations.
PM for sources.
The regulator circuit is pretty straight forward.. here's a current
regulating one
<http://led.linear1.org/a-
cheap-current-regulated-luxeon-star-driver-design/>
but I've mostly used voltage regulators
Have you worked with larger units for portraiture?
karl
