Optical Pass Filters

[old_tv_nut]

The early professional CCD cameras had strong infrared (and deep red) cut filters to match plumbicons, which had notoriously poor deep red response. None of these cameras could see the red phosphor of a CRT properly.

A local news show had stacks of monitors plus a CRT rear projector as background on the set. All the monitors needed color correction gels to reduce the green and blue output. The rear projo was actually two units with their images superimposed, so that there was enough output when the green and blue were attenuated and both red tubes were running full blast. [Edit - the pictures looked very pink to the eye, but neutral to the cameras).

These days, camera manufacturers are experimenting with extending the red response again, beyond what the eye can see, for a better match to the old film responses when doing digital cinema.