*Off-topic(sorry!): ULTIMATE GUIDE TO CUSTOM WHITE BALANCE

“Photometry” deals with measurement of light; it’s not clear what you mean when you use this term.

White balance is simply a means of defining white for the camera’s circuitry. It’s also possible to white balance in many NLE editing programs, defining white for the program’s color correction utility.

Manual white balance in camera is pretty straight-forward: Using the lighting that you will be shooting with, set up a white card (paper, cardboard, etc.,) and zoom in until the card entirely fills the viewfinder. Press the white balance button on the camera, wait until the white balance icon stops flashing, and you’re finished.

Be sure to white balance each time you change lighting setups.

I’m not familiar with your camera but presumably there is some method of creating manual white balance, in which case do as I suggested above.

As for not being able to fill the screen with a white card — use auto white balance, or don’t white balance at all. Any decent editing software will allow you to white balance in post, and although this isn’t ideal, it works. In this case you select something your picture that should be white and the software will adjust the entire image. You are identifying “white” and the software calculates “If this is white, than adjustments should be made to all the colors in this clip accordingly.”

Don’t make too much out of white balance. If you do “run and gun” video you may never have an opportunity to white balance throughout a day of shooting. In that instance I just leave white balance in auto and trust my cameras.