Alex Benjamin
Subscriber
You don't have to and you wouldn't be able to if you have not captured the shadow details.
This.
If you feel your photo looks better without shadow detail, you can always darken the shadows in the darkroom. If you feel it looks better with shadow (or highlight) detail and you don't have them on the negative, nothing much you can do.
Reminds me of this quote from an interview I was just reading with the great Magnum printer Pablo Inirio: "I’d rather have a negative that’s over-exposed than under-exposed. Under-exposed is hard because you want to bring out as much detail as you can—if you feel it’s necessary to the picture—and that’s hard to do without going grey. So when that happens, you end up working on a higher-grade paper with more black and white, which means less grey but you lose in the highlights, or you have to spend a lot more time printing for the highlights. So that’s hard. Whereas if it’s overexposed, I can always just add more time."
The "if you feel it's necessary to the picture" is the most important part of that quote.
To come back to the OP, yeah, a lot of zone system practitioners have gone way overboard on the scientific side of things. That said, the "don't worry about exposure and metering modern black and white film has so much latitude you can over- or under-expose by 1 or 2 stops it won't make a difference" that I've ran into more and more often lately, I find no better.