I am shooting several interviews that need to match footage that has already been shot. The existing footage was shot with color temp set to 3100k. Once I set the color temp on my camera, do I have to white balance? or will a custom white balance over-rule the color temp settings?

Setting the temperature manually precludes your ability to set white balance through the lens until you move the WB switch to either A or B.

But this begs another issue. Unless you are shooting all the interviews in the same place with the exact same lighting your footage will not match based upon a constant color temperature. A WB card is a much better way to get consistent looking footage.

thanks.

yes, the interviews that I am shooting will take place in the same location with the same lighting.

so, all I have to do is set the color temperature, and I should be all set. correct?