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FrozenGate by Avery

Photo of red laser dot is WHITE !!

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Apr 4, 2009
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Maybe more a photography problem, but when taking a picture of the red laser dot results in white. Maybe the depth of image of a camera is far less than the human eye (which sees it as really BRIGHT RED).
I used a Canon eos 40 and show in RAW which I converted to jpg.

Does anybody take better pics of a laser dot ?
 

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The CCD sensor is simply over saturated with light, so it looks white, happens often with cameras.
 
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The CCD sensor is simply over saturated with light, so it looks white, happens often with low quality cameras.

To be fair...
Even a nice DSLR like the Rebel is prone to overexposure. It just depends on the settings you use and the conditions you shoot in. ;)

Laser light is much more intense than your regular light source and even a photo of a 5mW red may appear that way when shot close up.
You can compensate some by shooting with flash or with the lights on, or by adjusting camera settings.
 
But this is not a low quality phonecam but a modest SLR with a CMOS sensor. But you're right the sensor can be oversaturated, but why is our own 'sensor' (the retina) not oversaturated and do we still see the (very bright) red color ? Because the green and blue cones in the eyes are not oversaturated unlike a CCD/CMOS sensor?
 
Because our Irises dilate to adjust the amount of light that enters the eye.
 
I did not see you had an SLR :oops:

My Canon Rebel T1I does the same thing.

Your brain is certainly the best image processing system you can find, it simply makes the light look less powerful, so you don't get such light over saturation, also the light capture system is not the same. What happens here is that the light is so intense it goes through all of the different filters that cover the silicon sensors (red, green, blue; three sensors in a pixel) and makes the light look white.
 
But this is not a low quality phonecam but a modest SLR with a CMOS sensor. But you're right the sensor can be oversaturated, but why is our own 'sensor' (the retina) not oversaturated and do we still see the (very bright) red color ? Because the green and blue cones in the eyes are not oversaturated unlike a CCD/CMOS sensor?

They do. The chemicals that respond to the light get depleted, and that's why you see ghosts when you look away. As to why you sense "white" light on a CMOS sensor, the laser may be intense enough to overcome the filtering provided by the bayer filter on the CMOS sensor that is responsible for discriminating between colors. The light of a certain intensity just passes through the filter and registers as a signal. The cones in the eye, on the other hand, don't use that kind of filtering.
 





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