Forums > MaxMSP

Infrared light, what to get?

April 29, 2010 | 12:58 am

I am having an installation where the cam tracks people in 3 distinct positions left center right.
I want to know which infrared light to buy, basically one that gives me a whole range.
problem with infrared led’s is that they usually only light the led but not the space around. I am looking for one
that has the ability to light up a whole room.
what do you guys suggest?

thanks


April 29, 2010 | 1:42 pm

This will depend greatly on the size of the space you are illuminating.

In my experience low cost IR led products generally have hot spots as you describe, even if they proclaim to be wide angle. There are some high end models that supposedly deal with this, but I’d recommend just getting several cheaper illuminators and using them to create as even a light field as possible.

Here’s one:

http://www.amazon.com/YY-Trade-Inc-WideAngle-Illuminator/dp/B001P2E4U4

I have no experience with this unit. I have, however, used models from Scene electronics, which sell directly on Ebay and also through some wholesale websites now.

One strategy to deal with the hotspots is to place a diffusion filter over the illuminator, which reduces the amount of light in the room but does create a more even field. Lee makes some good filters for this purpose.


April 29, 2010 | 9:57 pm

Thank you very much I am going to buy a couple of wideangel illuminators, thanks again


April 30, 2010 | 6:09 am

Also, the right combination of gels, can’t remember specifics, but lots of stuff works over the top of a bright light, like a shoplight, with a diffuser, and then the gels give a WHOLE lot of IR light and is barely visable. It will get Hot though. Even better is to use focusable theater lights.

Other solutions are found in the book "spy gadgets for the evil genius". You can drive LED arrarys with PWM to get up to 10X increase in brightness. Also you can use near-IR lasers (20-$40) and the appropriate beam-spreading lens to get lots of IR for low energy input. CAUTION — before IR light is spread it is dangerously bright laser, (20-80mw) – and invisible! So make sure you don’t look at it or a reflection, and that the beam is truly totally spread out without hotspots before exposing it to public. And make sure the lens can’t fall off. You can use a BW video camera to inspect the beam. Another note of caution. Don’t point a semi-focused IR laser at your camera as it will do the same to your uni-brain as it does to your eyes.

A third option, (can you tell I’ve been doing a lot of this sort of thing) is to use heat lamps, like you find in bathrooms. Lots of IR, and not much visible. And i think they look really cool. No filters needed.


May 3, 2010 | 6:56 pm

Christopher, thanks that is very helpful , I have the exhibit this friday I am waiting for the infrared lights jesse suggested to arrive, If they are to much of a spotlight I will have to follow your A,or B advice. Thank you a lot.


May 3, 2010 | 7:34 pm

hi,

i’m using a setup with theatre filters which is cheap and very effective.
basically any kind of ‘warm’ lamp will work.. regular wolfram bulbs are perfect, but theatre spots, halogen etc also work great.

use 1 congo blue and 2 primary reds, both for your lights and camera. this way the camera only ‘sees’ stuff in the same spectrum as your ir source. (e.g it’s almost blind for tubelights going on and off etc.)

if you’re gonna use strong lights, try to get the hi temperature filters.
i’m using LEE filters, but Rosco also has similar stuff.

good luck with your project!
drop a link here when it’s finished

best,
daan.


May 3, 2010 | 7:37 pm

o wait, correction:

2 congo blue and 1 primary red…


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