Rodney, your questions are leading me to believe that you have a bit of confusion going on. Please let me help if I can.
To understand metering you need to first grasp how they work.
Fundamentally, there are 2 kinds of light meters. Incident and reflective.
Incident meters are the kind that read the light falling on the subject. They are usually hand held. You've seen them in use I'm sure. With an incident meter, the reading isn't fooled by subjects that are excessively bright, or excessively dark. You just hold them up and point the meter in the direction of the camera and it'll tell you what f stop to use with any given shutter speed. Obviously you use the camera set on Manual Mode so you control the shutter speed and aperture. Incident metering is very accurate.
The other type is reflective metering. It reads the light bouncing off of a subject (reflective), They are the kind found in cameras. Modern cameras take this reading inside the camera through the lens (TTL). These meters are calibrated to correctly read a medium gray. It is the standard all camera meters are set to.
So, if you were shooting a white brick wall, the meter would set the shutter speed and/or aperture to make that white wall a medium gray.... resulting in an underexposed image. If you were photographing a solid black wall, the meter would give you a different reading but result in a medium gray wall also ... in other words, an overexposed image.
Modern meters have different emphasis placed on parts of the overall image in the viewfinder to try and help even things out. But it will never be enough when the scene conditions are biased too far in either the light or dark way. If you tried to photograph a snow scene in bright sunlight without compensating the meter, the snow will be a muddy gray... even with the most advanced in-camera meter.
In the end, you have to learn how to recognize what parts of a scene represent the medium gray that you need to meter. large areas of grass get pretty close. Meter it and lock in the reading.
Now here's the hard one to grasp, but it is true: If a scene is excessively bright and contains dominate whites, you compensate the meter to the PLUS (+) side to add more exposure. Seems counterintuitive, but that's what is necessary.
If a scene is excessively dark or contains dominate blacks, or dark colors like royal blue, deep reds, etc., you compensate the meter to the Minus side (-).
Now, quite often you run across a scene that perfectly balances the darks and lights and needs no compensation at all.
Now, on to film. Unlike digital or slide film, negative film has a wide latitude for incorrect exposures. But that latitude is mostly to the overexposure side and has much less tolerance for underexposure. That is why you often see advice to set the ISO on the camera to a 1/2 or even full stop lower than that marked on the film. I often shoot Tri-X 400 set to ISO 320 for ex&le.
There is a lot more subtile details and exceptions to this information, but that is the basics.
Hope it helps, if even just a little.
To understand metering you need to first grasp how they work.
Fundamentally, there are 2 kinds of light meters. Incident and reflective.
Incident meters are the kind that read the light falling on the subject. They are usually hand held. You've seen them in use I'm sure. With an incident meter, the reading isn't fooled by subjects that are excessively bright, or excessively dark. You just hold them up and point the meter in the direction of the camera and it'll tell you what f stop to use with any given shutter speed. Obviously you use the camera set on Manual Mode so you control the shutter speed and aperture. Incident metering is very accurate.
The other type is reflective metering. It reads the light bouncing off of a subject (reflective), They are the kind found in cameras. Modern cameras take this reading inside the camera through the lens (TTL). These meters are calibrated to correctly read a medium gray. It is the standard all camera meters are set to.
So, if you were shooting a white brick wall, the meter would set the shutter speed and/or aperture to make that white wall a medium gray.... resulting in an underexposed image. If you were photographing a solid black wall, the meter would give you a different reading but result in a medium gray wall also ... in other words, an overexposed image.
Modern meters have different emphasis placed on parts of the overall image in the viewfinder to try and help even things out. But it will never be enough when the scene conditions are biased too far in either the light or dark way. If you tried to photograph a snow scene in bright sunlight without compensating the meter, the snow will be a muddy gray... even with the most advanced in-camera meter.
In the end, you have to learn how to recognize what parts of a scene represent the medium gray that you need to meter. large areas of grass get pretty close. Meter it and lock in the reading.
Now here's the hard one to grasp, but it is true: If a scene is excessively bright and contains dominate whites, you compensate the meter to the PLUS (+) side to add more exposure. Seems counterintuitive, but that's what is necessary.
If a scene is excessively dark or contains dominate blacks, or dark colors like royal blue, deep reds, etc., you compensate the meter to the Minus side (-).
Now, quite often you run across a scene that perfectly balances the darks and lights and needs no compensation at all.
Now, on to film. Unlike digital or slide film, negative film has a wide latitude for incorrect exposures. But that latitude is mostly to the overexposure side and has much less tolerance for underexposure. That is why you often see advice to set the ISO on the camera to a 1/2 or even full stop lower than that marked on the film. I often shoot Tri-X 400 set to ISO 320 for ex&le.
There is a lot more subtile details and exceptions to this information, but that is the basics.
Hope it helps, if even just a little.