What kind of general purpose filter do you use when you take out door portrait shots in overcast wheather? I love the colors of E100VS and Provia 400X, but only as long as the sun shines. As soon as the subject enters the shade or the sky gets overcast, skin colors end up somewhere between poor and downright awful. Since slide film has so little latitude, not even filtering in the dark room or even a hybrid work flow can save these images.

Is this possible? Is there such a "slap it on and the result will be in the ball park" filter for these light conditions? Would a KR6 filter do the job? Or is slide film just not an option unless one puts in great effort into color balancing?