it's a reasonable question, fred, and as you suspect it is quite subjective .... i also had to chuckle at your practical definition of 'your own shadow'-- easy to tell you're from the land of the sun, unlike me here in oregon and vaughn in n.calif., where we often don't cast any shadows at all in the landscape ..... anyway, i remember wrestling with this very issue back when i was figuring out the zone system some 20 years back, and the answer i came to after a while was rather simple -- it is the darkest area in the scene where i wanted to be sure to retain detail in the print ..... when shooting 4x5 for enlargements, i would place that shadow on Z3 (two stops under the z5 reading) .... now that i exclusively contact print with larger formats, i find that i must place that shadow on Z4 (whether contacting in silver or pt/pd) -- i don't know why this is the case, frankly, but have learned from experience that that's what works for me .... can anyone enlighten me why i could pull shadow detail from Z3 when enlarging 4x5, but need a Z4 for that same shadow when contact printing fromm 8x10?
rich