d13eec88   
   From: Bret_E_Cahill@yahoo.com   
      
   > > It might be more cost effective to just buy a lot of cheap IR LEDs and   
   > > use a conventional camera, first testing for an IR cut off filter with   
   > > a single cheap IR LED.   
   >   
   > What is cost effective depends on what you're trying to accomplish.   
   > Would a $10,000 multi-camera motion sensing alarm system be expensive if   
   > it saves your life?   
      
   There's no personal safety concern here.   A cost benefit risk   
   analysis is all that is necessary.  The cost needs to be < $100.   
      
   > That could  be more effective than hiring 24/7   
   > security guards and certainly less expensive.   
      
   This will only last a couple months if not weeks or days.   
      
   > With a wide field and short range (maybe 50 yards) system a bunch of   
   > LEDs may work well.  For long range (300 yards+) a telephoto lens and a   
   > single diode laser focused to the same area as the camera's field of   
   > view will work much better for the money spent.   
      
   20 - 50 m is all that is necessary   
      
   > What do you want to view in the infrared?  (humans, animals,   
      
   Every less-than-savory type in town passes through this alley at least   
   once a week.  That's all that needs to be photographed.   
      
   > IR emitters   
      
   I just checked with a Samsung Digimax 530 that's super sensitive to   
   850 nm IR  and apparently no one has done anything in the near IR yet.   
      
   I'm not going to duplicate efforts.   
      
   > (such as other humans using cheap night vision equipment).   
   > Do you want to also view in color in the daytime?   
      
   10:00 pm to 3:00 am is all that's necessary -- 8 GB in 15 f/s movie   
   mode.   
      
   > At what maximum distance?   There is little transmission loss through   
   > the atmosphere, but all divergent light sources obey the inverse square   
   > law.  That applies twice for a light near the camera illuminating a   
   > target.  At long range atmospheric backscatter can blind the camera from   
   > a nearby illuminator if the outgoing path passes in between the camera   
   > and the target.   
   >   
   > In what environment? (indoor, outdoor, bad weather)   
   >   
   > If outdoor, in city night illumination,  moonlight, under clear sky,   
   > overcast?   
   >   
   > Do you want to simply view the scene? (monitor, computer)   
      
   > Do you want to capture images either as still or video?   
      
   Video might be the easiest cheapest way to go if memory isn't an   
   issue.   
      
   > Do you want to do motion sensing with alarm  and/or storage of the images?   
      
   Just store the images, preferably to a hard drive to save money on an   
   8 GB card.   
      
   > Do you have a computer with USB2.0? A computer with firewire? A computer   
   > with an NTSC (or PAL) framegrabber?  Ethernet WiFi?  All of those can   
   > carry video images depending on camera selection. Image processing can   
   > be done in the camera or in the display computer.   
   >   
   > Do you need to be covert to a viewer with no night vision capability? Do   
   > you need to be covert to a viewer with night vision capability?   
   >   
   > What resolution do you need to be able to recognize at what distance,   
   > for example,   tell a human from a deer at 500 yards or identify a   
   > particular human as friend or foe at 50 yards.   
      
   Something a little better than those sorry day time images the FBI is   
   putting out for the marathon bombers.   
      
      
   Bret Cahill   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)