Note to Self: Spot Metering Trick

Outdoor Photography magazine offers the following trick for preserving highlight details, The idea is to set exposure to place the critical feature in its correct zone in accordance with Ansel Adams' Zone System. A white highlight with just a little detail or texture should be zone 7, two stops overexposed; light rock should be zone 6, one stop over. So the procedure:

• Tightly spot meter the highlight for the appropriate exposure, +2 or +1. 
• Lock in that exposure or set it manually. 
• Recompose and shoot. 

The automatic settings usually do just fine, but there are times when it'd be nice to lock in the perfect exposure on a detail-highlight area without shooting a bunch of insurance exposures (or RAW).