Where can one find a table of B-Vs for variables? Or is this something I do myself, using the B and G channels from my dslr's raw data?
Capital letters are used for Standard Values. I assume that this is what you are looking for. Go to the web page, select "Observing" Tab, then "Star Charts". Enter the object name or coordinates, etc,, and select "Photometry Table". A Table of U, B, V, B-V, R, Ic, and nir Standard values will be displayed. You can print both the finder chart and the Photometry Table for future use.
You can ascertain the B-V of variables in the VSD database using SeqPlot
You can also get a rough idea of the color of your variables by noting the spectral type in VSX.
Be aware that B-V can and does change during the cycle of many types of variables, so one of the things we strive to get AAVSO observers to do is provide transformed color and magnitude information when you submit data. It's essentially wide band spectroscopy, and can yield important science results.
Mike Simonsen (SXN)
I guess you need B-V in order to transform TG magnitudes to V using the Citizens Sky DSLR photometry tutorial. I wouldn't do this.
Instead just submit IMHO the TG magnitudes to AAVSO.
If you realy want to transform you TG magnitudes to V I'd recommend first to determine the transformation coefficients of your camera using the methode described here: http://reductionism.net.seanic.net/CCD_TE/cte.html