Post by iawatcher on Aug 21, 2011 9:19:38 GMT -6
I found this great post on the RRP board about infrared and why it doesn't affect the birds:
Night Camera Views
« Reply #10801 on: Today at 09:00:21 »
Greetings All,
With all due respect to those who have posted their thoughts as to how the "night" cameras work, I feel obligated to point out that there seems to be a basic misunderstanding as to what is happening.
What one needs to first understand is that neither camera emits light, infrared or otherwise. A camera can only "see" light which is reflected from its subject(s). The infrared light source which illuminates "our" nest is not contained in either camera, but is a separate entity. It does not "track" with the cameras, but remains pointed at the nest.
For a wonderful explanation of what infrared light is, I recommend the following: science.hq.nasa.gov/kids/imagers/ems/infrared.html
You may recall that the buzz/hum which we found so annoying would often start several minutes before the view changed to black and white. That was the infrared light turning on. The view did not change because there was still sufficient ambient light to continue illuminating the nest, and the cameras had not switched to infrared capable.
Both cameras, the fixed and the PTZ, are capable of detecting infrared when switched into correct mode.
Again, the important point to remember is that the cameras merely detect, they do not emit, infrared light. Many of us recall that when the view was, for a few days, only from the fixed, wider angle camera, we could still see the E's at night.
When the cameras switched to IR capable, what we saw passing across the view was a filter, not a lens changing.
The view changed to black and white at that time. This, I suspect, was for 2 reasons.
One, to have infrared color capabilities would probably entail added costs, and
Two, the view would have been totally unnatural.
(In the above link, look at the cat picture, imagine the eagles . . .)
Again, there was usually ambient "regular" light remaining, and the cameras still could "see" it. If one had looked closely, one would have seen that leaves closer to the camera and light source began to take on the ghostly glow as they were reflecting the infrared. More distant leaves, and the background trees and grasses received insufficient infrared light.
(Trust me; you do not want to get me started explaining inverse square light falloff.)
As the daylight faded, the background faded to black, but the nest, its occupants, and--to a lesser degree, due to that falloff thing--the leaves and branches of the cottonwood, could be seen as they reflected the infrared light which the cameras were now able to detect and transmit to us.
Since infrared light is in fact light, objects in view cast normal shadows. Remember that a shadow is not thing unto itself; it's merely an area receiving less illumination than its surroundings. Since eagle eyes do not detect the IR light, there is no visible distinction between the illuminated areas and the shadowed areas.
Night Camera Views
« Reply #10801 on: Today at 09:00:21 »
Greetings All,
With all due respect to those who have posted their thoughts as to how the "night" cameras work, I feel obligated to point out that there seems to be a basic misunderstanding as to what is happening.
What one needs to first understand is that neither camera emits light, infrared or otherwise. A camera can only "see" light which is reflected from its subject(s). The infrared light source which illuminates "our" nest is not contained in either camera, but is a separate entity. It does not "track" with the cameras, but remains pointed at the nest.
For a wonderful explanation of what infrared light is, I recommend the following: science.hq.nasa.gov/kids/imagers/ems/infrared.html
You may recall that the buzz/hum which we found so annoying would often start several minutes before the view changed to black and white. That was the infrared light turning on. The view did not change because there was still sufficient ambient light to continue illuminating the nest, and the cameras had not switched to infrared capable.
Both cameras, the fixed and the PTZ, are capable of detecting infrared when switched into correct mode.
Again, the important point to remember is that the cameras merely detect, they do not emit, infrared light. Many of us recall that when the view was, for a few days, only from the fixed, wider angle camera, we could still see the E's at night.
When the cameras switched to IR capable, what we saw passing across the view was a filter, not a lens changing.
The view changed to black and white at that time. This, I suspect, was for 2 reasons.
One, to have infrared color capabilities would probably entail added costs, and
Two, the view would have been totally unnatural.
(In the above link, look at the cat picture, imagine the eagles . . .)
Again, there was usually ambient "regular" light remaining, and the cameras still could "see" it. If one had looked closely, one would have seen that leaves closer to the camera and light source began to take on the ghostly glow as they were reflecting the infrared. More distant leaves, and the background trees and grasses received insufficient infrared light.
(Trust me; you do not want to get me started explaining inverse square light falloff.)
As the daylight faded, the background faded to black, but the nest, its occupants, and--to a lesser degree, due to that falloff thing--the leaves and branches of the cottonwood, could be seen as they reflected the infrared light which the cameras were now able to detect and transmit to us.
Since infrared light is in fact light, objects in view cast normal shadows. Remember that a shadow is not thing unto itself; it's merely an area receiving less illumination than its surroundings. Since eagle eyes do not detect the IR light, there is no visible distinction between the illuminated areas and the shadowed areas.