Re: Will IR Illuminator work with any CCD Camera?

[John Popelish <jpopelish@xxxxxxxx>]

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.