This has been sitting on my to-do list for a bit, so let's try and finally get this done.
Above is a collection of charts for values in different lighting conditions, plus a Reilly Value scale. On the left are different conditions for Form Lighting (Which is defined by Faragasso as the typical indoor lighting that life drawing and still life models are under,) while on the right are the conditions for Sunlight and Rim Lighting (light that is illuminating a figure from the behind.) There is also front lighting, but that's one I'm still trying to sort my brain around, so for the time being I've left it out.
These charts have been pretty invaluable in helping me get a jump start on getting proper values down - too often I don't push values enough, and it ends up as a grey, soupy mess when it's done, without any sort of clear focal point. So let's try and dissect one of these charts, yeah?
They're actually pretty easy to decode - there's a light side column, and a shadow side column. On each column, you have a base value that that translates over to what the value may appear as in either the light, or shadow. For example, say your object is a value of 5 (that's middle of the middle of the middly grey, pretty much), It will appear as a value of 7 in the light, and a 2 in the shadow. If you're not quite grasping it, look at the chart again reread this paragraph - it'll grab you eventually.
Here's an example of two imaginative still lifes made using these value systems. The top uses the Sunlight chart, while the bottom is the Form Light chart. Can you guess what the base values are of the objects based off the light and dark values listed?
This whole system actually becomes really easy to understand once you try it out a few times. And like all formulas, it shouldn't be the end-all, but for someone that has trouble pushing their values, it's a valuable stepping stone to see accurate values and be more confident in their value choices.
Here's another example, a before/after of three figures. I first chose base values for the different parts, then applied values according to the Form Light chart. As you can see, it yielded some pretty fast and decent results. You still need to understand how light and shadows work, though, otherwise you'll be placing random shadow shapes everywhere without thought given to form, cast shadows, etc.
This is only the surface of this whole system. There's more complicated variables that take away the initial simplicity of it, and that's just without adding color (once that's added in, it becomes inevitabley more complex...something I have yet to figure out all the way.) For the start though, the use of this chart and value scale is something that should be taken and used with gusto.
(If you'd like to learn more about Frank Reilly's methods, I can't recommend John Ennis' blog "The Reilly Papers" enough. You can find a link for it in the sidebar, or in my previous post.)