Quote Originally Posted by gareth harper
Exactly, keep em clean, and when you see flare shade the lens. Now do you really need an assiatant to do that?
In the photo studios I worked in, that's exactly what assistants did, among myriad other things. However, for color correction to transparency film in the studio, we used gels in filter holders inside the view cameras to avoid flare, as well as always shielding the lens from the light source with a shade, gobo, flag, or whatever other means necessary. There are gel filter holders that clamp to the outside of the lens barrel with spring metal bands and fit inside the typical 4x5 or larger bellows (mostly non-tapered in studio cameras). Gels were kept very clean and replaced when marred or smudged.

If you have the interior room in a view camera, it's also much easier to carry one filter holder and a packet of different gel filters in the field. It really keeps down the bulk and weight.