Comment by MontyCarloHall
3 years ago
>what's your take on the dynamic range in over-exposing film vs under-exposing digital?
You should actually overexpose digital (without blowing any highlights) to maximize dynamic range.
Our eyes perceive brightness logarithmically — given something emitting P photons perceived as brightness B, something emitting 2P photons will be perceived as brightness B+1, while something emitting 0.5P photons will be perceived as brightness B-1.
Image sensors are linear and discrete. So going from R,G,B=1,1,1 to 2,2,2 represents a doubling of photons captured, and thus be perceived by the eye as going from B to B+1. But 2,2,2->4,4,4 will go to B+2, 4,4,4->8,8,8 to B+3, etc.
Thus, there is only one bit of dynamic range going from B to B+1, 2 bits of dynamic range from B+1 to B+2, 3 bits from B+2 to B+3, and 2^N bits from B+N-1 to B+N. That’s why you want as much brightness information as possible close to saturating the sensor, since that’s where the most bits of dynamic range are.
This is called “exposing to the right” [0].
[0] https://digital-photography-school.com/exposing-to-the-right...
While it’s true you should in theory expose to the right, it’s realistically a little riskier unless your environment is well controlled or you’re willing to potentially clip some highlights. So for landscapes that you spend a while composing and metering, it makes sense, but for street photography or something where there’s a ton of contrast, I wouldn’t recommend it because you’ll overexpose more often than not and unlike with film, it’s harder (and maybe impossible) to recover detail from highlights.
Since storage is cheap, I’d rather just bracket my shots that need it than expose to the right, reducing the potential of losing a good shot by losing some highlight detail.