[mythtv-users] IR Blaster sadness

[Brian Wood]

On Mar 23, 2008, at 7:36 AM, Adolfo R. Brandes wrote:
> On Fri, Mar 21, 2008 at 11:17 PM, Brian Wood <beww at beww.org> wrote:
>> If you want to directly determine if the IR diode is actually  
>> emitting
>> anything you can observe it through the viewfinder of a digital still
>> camera or most camcorders.
>
>  Amazing, I had no idea digital cameras would do that!  Does this
> mean one could use the camera for night vision? ;)

Not quite, unless somebody was using one of the WWII vintage high- 
intensity IR illuminators used with the "Sniperscopes".

Although most digital cameras will respond to light in the IR range  
they do not have any significant light amplification abilities. With  
"gain" a camera might give you a 2x or 4x light gain, a modern night  
vision device amplifies light by 30,000x (gen 1) to over 100,000x (gen  
3, with the GaAs microchannel plates).

The IR illuminators used with modern NV devices are very low level (a  
few LEDs at most) because of the high-gain factor used with the  
viewers. The IR produced by things like warm bodies is of a different  
wavelength and much too low-level to be visible by typical cameras, or  
even normal nv devices. Some specialized devices used by fire  
departments and the military are designed to see this type of IR  
radiation.

There was a flap a while back about some camcorders allowing "X-Ray"  
vision, caused by the fact that some very light clothing is more  
transparent to IR than to visible light, but I think it was more media  
hype than fact.

But, NV devices are pretty cheap these days, especially the Russian- 
made Gen 1 stuff, if you don't mind "fun house" optical distortions.

But as I mentioned initially, the effect can be useful for  
troubleshooting IR remotes.

beww