Amount of light needed to capture images

[nitro]

Hi all,

I'm working in application where a camera needs to see in a dark closed area. Imagine a small box, say 8"x8" and there is a camera trying to record inside. In order to get images, we need some light. The problem is how to determine how much light is needed without being too little light or too much light. The camera will be moving so the right amount of light is crucial

Could someone point me to directions on how to compute the amount of light needed for such application?

Thanks

 

[mgb_phys]

In theory from the read noise and QE of the CCD, shutter speed, the dynamic range and noise of the ADC, the algorithms in the dynamic gain circuit and the optical design of the lens - together with the spectral characteristics of the light source you can calculate it.

In practice - try it.

 

[nitro]

Thanks for the reply,

definitely a trial and error will be needed. But some theory is good to spec out a prototype


Does anybody know where to find information about light formation, to be able to at least estimate the amount of light needed?

Thx

 

[DavidSnider]

What kind of camera? Also, the acceptable level of image quality depends on what the images are being used for..

 

[mgb_phys]

If this is a video camera the sensitivity will probably be quoted in lux http://en.wikipedia.org/wiki/Lux
For a still camera it's easiest to work in ev http://en.wikipedia.org/wiki/Exposure_value

In practice it really is complicated and depends a lot on how good (SNR) an image you need.

 

[nitro]

I'm working with a moving video camera and as you might know if there is not enough light lots of frames will be blurry due to slow shutter speed and the need to get as much light as possible.
It seems that the best way of proceeding is lots of testing and experimenting with different settings. However, i was hoping that someone could point me to resources to be be able to at least roughly estimate the amount of light i would need

if i have some estimate I could buy some lights and see how things work

thanks a lot

 

[reasonableman]

If you already have the camera record some scenes that are an acceptable quality and extrapolate from that...

For a trivial example if you need to expose for a second to get a decent image, but the thing you want to record requires 0.1 s framing, you'll need 10 times more light!