Re: Will IR Illuminator work with any CCD Camera?

[Charles Sullivan <cwsulliv@xxxxxxxxxxxx>]

On Sun, 31 Dec 2006 21:05:29 -0500, John Popelish wrote:

> Charles Sullivan wrote:
>
>> As I understand it, the reason for including an IR filter is that the
>> focal planes for IR and visible light are different enough that there's
>> a noticeable blur in the image if both sources are present, as in
>> sunlight.
>>
>> I don't know to what extent this can be corrected by an achromatic
>> lens as is used to correct for chromatic aberation on quality visible
>> light cameras.
>
> There is another basic reason to filter out IR.  What color
> do you assign to its signal?   It represents illumination
> you can't see, so no matter what you do with it, it distorts
> the visible representation of the scene.   The more
> expensive the camera (assuming it is designed to capture
> visible images), the more likely that it will include a
> short pass filter to block light that silicon can see that
> you cannot.  Cheap cameras that have none usually show the
> IR as green, for some reason.  Possibly an artifact of the
> non-ideal bandpass characteristic of the narrow band green
> filter.

Good point!!!