waitaminute - the ZS is used for metering with B&W film.
And it's used because if a scene has areas that are dark, medium and bright, one needs to be careful not to meter on the 'wrong' thing, which would result in either shadows lost or highlights blown. It's a way to 'balance' out the range in B&W photography.
In the same way that I would spot meter the sky that is backlighting my subject to create a silhouette (dark shadows with no detail, but texture shows up in the sky behind him/her), or to use the other extreme, I would meter for my subject, and let the sky blow out (behaving like a white backdrop). in these two cases, there isn't much of a middle ground.
But let's say I have a street scene that is lit by harsh midday sun. There's a veranda overhanging past a storefront, with an old guy on a rocking chair smoking his pipe in the shade. Inside the shop are pretty deep shadows.
In this case, if I wanted to expose the scene 'properly' to capture the old guy, I could meter him if I wanted to expose some bits inside the shop, or I could expose slightly closer to the edge where the sun is getting into the veranda, which would expose the old guy, but I would risk a bit of shadow for a bit of the sky.
But here's the doozy:
We're assuming hat one meter is the same as the next. That's pretty much been my assumption up until I read that article (see post #1 in this thread) where I learn that the meter on the Zeiss Ikon / Voigtlander Bessa cameras are 'calibrated' for slide film. Based on my experience and what I've been told about slide film, I should be careful not to overexposure, so I don't end up with blown highlights. If this is the case, then I'm guessing that the recommended exposure from the meter is actually 1/3 to 2/3 stop underexposed, as compared to if I were shooting with film, vis a vis, if I were to shoot with film, I 'should' overexpose against the recommended setting (let's say 1/125) by shooting at 1/80 or 1/100 at the same aperture.
Now, if the Voigtlander meters were calibrated for slide film (hence readings tend to result in a slight underexposure when used on negative film), then I have three choices when using the same camera to shoot with negative film - either I
a. set the camera's ISO dial to 1/3 to 2/3 stop slow (i.e. ISO320 when using ISO400 film, and tell the lab to develop as ISO320), or
b. set exposure compensation to +1/3 to +2/3, or
c. manually 'add' 1/3 to 2/3 stops by opening up the aperture or slowing the shutter for every shot.
Now, if this was the case with Voigtlander, does anyone know if the meters on the RZ67 AE prism finder, the Hasselblad PME5, the Mamiya 645AFD II, Nikon, etc are similarly calibrated for slide or negative film?
Or is a meter a meter, and regardless of the brand/model, at a given/specific EV (e.g. EV10), f/8 would ALWAYS yield 1/125 on ISO100?