The phrase "expose for the shadows" is thrown around easily in photographic circles. Unfortunately, like most rules of thumb, if not accompanied by further understanding of its meaning, following the "rule" will make your results worse than they would be shooting with an in-camera averaging or patterned reading, automatic exposure, or even an educated guess or pre-printed exposure chart.
Additionally, and very importantly, the term is designed to be used in conjunction with "develop for the highlights". If the second half of the rule is not heeded as well, you can really get some mangled exposures, with bulletproof densities on the highlight areas of your negatives. Yet again: worse than just going with what your camera sez to do.
"Expose for the shadows" does not mean to meter a shadow and employ the exposure your meter sez to use. It means meter the shadows and expose to place them at the desired negative density that will make them easily print to *your desired tone* and contain *your desired amount of detail*.
If you expose for the shadows straight off of the meter, your shadows will easily print to a middle grey, and the over all shot will be one to four stops over a decent exposure. (It is such a wide range of possible amounts of overexposure because there is a wide range of what you might *want* the shadows to look like.)
Your [reflected light] meter *does not* tell you what the "right" exposure is. It tells you how to make something easily print to a middle grey, and nothing else. All it does is give you that one reference exposure that will make the metered object easily print to a middle grey tone. It is up to you to know what it is telling you, and make your exposure decisions based on the knowledge of what exposure will render the metered area as middle grey.
In other words, you need to decide what kind of grey you want the metered area to be on the print. It is likely not middle grey. To make something darker than middle grey, you need to give less exposure than the meter suggested. Vise Versa for areas that you want lighter than middle grey. You can reduce exposure from the meter reading by one stop if you want it to just be a little darker than medium grey, two stops if you want it dark grey but still with detail, three stops if you want it very dark grey with some texture but no detail, four stops if you want it to be nearly black with no detail or texture, and five stops if you want it to be totally black. Vise versa for the lighter end of the gray scale.
This all assuming that the EI you are using gives you accurate placement.
This opens another can of worms...
There are three basic ideas behind the practice of "placement" of print tones (AKA the zone system), and one preliminary fundamental idea:
0. *The negative is an intermediary step on the way from 3D world to 2D print.* Your quest is not to get a "perfect" negative as defined by the books or anybody but you. The quest is to get *the print that you want*. To get this, *you need to know what you want*! This is an artistic/aesthetic choice and has nothing to do with technique. It has everything to do with *visualization*. Then, on the technical side, you have to know how to get a negative that will let you get that print. Basically, this entails:
1. Figuring out an EI (film sensitivity input into a light meter, such as 100, 400, etc.). This lets you *predictably place low tones where you want them to be on your PRINT*.
2. Figuring out a standard development procedure. This lets you know what development procedure will closely match *contrast at the scene* to *contrast on the negative* to *contrast on the PRINT*. (In practice, I find that this works out to simply be a reference point in most cases, and is rarely ever actually used. This is the step that lets you know where your highlights will end up if developed normally, thus tells you how to employ number 3
3. Figuring out altered developing procedures. This lets you change the relationships named in number 2 above. This is the main step in how you how to control the PRINT tones of the highlights.
To get what you want, all of these steps must be calibrated to *your* actual prints by eye, not just some magic "correct" negative densities that you got out of an Ansel Adams book.
Back to number 0, the zone system is just a tool to take a healthy amount of control over that intermediary step. Don't blow it up beyond what it is. it is a very easy system, and that is why it works so well, and is so popular, IMO. This is all about serving your idea of what your print should look like; nothing else. That is the part that most zone "users" *do not* get.
Sorry for the stupid book.
