Hello illuminati!
For an upcoming exhibition, I'm looking for LED lights that throw a somewhat narrow beam with good enough collimation to be used like a projector or gobo, but with less heat and (maybe) lower focus tolerances. I'm hoping to crowd-source the search, and you all can help by doing the following:
1. Aim your favorite light at the wall from a distance of 7.5 feet (~2.25 meters).
2. Stick a pen into the beam roughly 18" (~45cm) in front of the lens.
If your flashlight produces a nice uniform disk of light on the wall and your pen casts a crisp shadow with sharp edges, take a photo and post it here. Please list the make and model, rated output (lumens), and beam width or spot size. See my example below. I'll announce a winner once I've tested all the promising candidates.
Here's my idea of the ideal light:
* 15-25 degree beam = spot diameter of 22"-33" at 7' (50-80cm at 2m)
* uniformly bright spot with sharp shadows throughout
* fast fall-off and minimal spill outside the spot
* output in the range 300-700 lumens
* pleasant shade of white
* runs cool for hours
Most likely the only viable candidates will use aspheric lenses; on-axis reflectors tend to produce fuzzy double shadows and other artifacts.
For the curious, I'm going to buy 20 or so lights, cut off the battery barrels, connect to a DC power source, and use them to illuminate picture-forming lenses as in this video: http://www.youtube.com/watch?v=hNexu9a7blY
Modding flashlights may not be the way to go, so I'd also welcome recommendations for raw LED module + collimator pairs.
Thanks for your help!
-- optik
As an example, here's a photo of the spot from a "zoomable" mini Cree Q5 knockoff. The shadow is too fuzzy at the center of the spot; the beam is too wide (48 degrees); the spot is nonuniform and too dim (~180 lumen). This light originally seemed promising because it can be focused to throw a crisp image of the LED die on the wall, but it turned out that the focused beam is *not* collimated because the rays cross to form an inverted image of the die.
For an upcoming exhibition, I'm looking for LED lights that throw a somewhat narrow beam with good enough collimation to be used like a projector or gobo, but with less heat and (maybe) lower focus tolerances. I'm hoping to crowd-source the search, and you all can help by doing the following:
1. Aim your favorite light at the wall from a distance of 7.5 feet (~2.25 meters).
2. Stick a pen into the beam roughly 18" (~45cm) in front of the lens.
If your flashlight produces a nice uniform disk of light on the wall and your pen casts a crisp shadow with sharp edges, take a photo and post it here. Please list the make and model, rated output (lumens), and beam width or spot size. See my example below. I'll announce a winner once I've tested all the promising candidates.
Here's my idea of the ideal light:
* 15-25 degree beam = spot diameter of 22"-33" at 7' (50-80cm at 2m)
* uniformly bright spot with sharp shadows throughout
* fast fall-off and minimal spill outside the spot
* output in the range 300-700 lumens
* pleasant shade of white
* runs cool for hours
Most likely the only viable candidates will use aspheric lenses; on-axis reflectors tend to produce fuzzy double shadows and other artifacts.
For the curious, I'm going to buy 20 or so lights, cut off the battery barrels, connect to a DC power source, and use them to illuminate picture-forming lenses as in this video: http://www.youtube.com/watch?v=hNexu9a7blY
Modding flashlights may not be the way to go, so I'd also welcome recommendations for raw LED module + collimator pairs.
Thanks for your help!
-- optik
As an example, here's a photo of the spot from a "zoomable" mini Cree Q5 knockoff. The shadow is too fuzzy at the center of the spot; the beam is too wide (48 degrees); the spot is nonuniform and too dim (~180 lumen). This light originally seemed promising because it can be focused to throw a crisp image of the LED die on the wall, but it turned out that the focused beam is *not* collimated because the rays cross to form an inverted image of the die.
