You will need to calibrate your white balance. Read the manual for instructions specific to your camera model. The source of lighting does not matter, however, if you use two or more light sources, they should be the same type, otherwise the coin will be illuminated by different light temperatures, making it impossible to get a consistent result across the entire coin.
$26 bucks .... too cheap. If anyone wants to loan me the book, I'd greatly appreciate it. And or a PDF.
The way I interpret CRI is that it is independent of color shift, which is what white balance can compensate. I would think that a spectral power distribution that is nothing but spikes wouldn't work well, but from this article, it looks like I should throw out the CFLs I like and get consistently good results from. http://www.popularmechanics.com/tec...-fluorescent-vs-led-ultimate-light-bulb-test/ A good visual test would be to photograph a color checker under each of the light sources, with the white balance calibrated to the gray part of the color checker. Perhaps then you'd see how strong and weak parts of the spectrum manifest themselves visibly.
This isn't really a hobby where you can cheap out on books and expect to do well. Most books in this hobby will more than pay for themselves over time with what you can get out of the knowledge. This one is no exception.
Indeed you are right Jaelus. My book arrived today and I must say it's a wealth of information and valuable advice.......