The zone system divides a scene into 10 zones on the tonal scale (though there are variations of 9 and 11 zones). Every tonal range is assigned a zone. Every zone differs from the one before it by 1 stop, and from the one following it by 1 stop. So every zone change equals 1 stop difference. Zones are identified by roman numbers, with the middle tone (with 18% reflectance) being a zone V which is zone 5.
Photographers, usually are only concerned with zones III through VII (zones 3 through 7). The darkest part of a scene would fall into zone III, while the brightest part of a scene would fall into zone VII. Anything darker than zone III would render as pure black with no detail (under-exposed), while anything brighter than zone VII would render as pure white with no detail (over-exposed).
If you point your camera at an area with average reflectance and obtain the correct meter readings (a zero on the light meter), that area would be rendered as average. If you open up your lens or slow down your shutter speed by one stop, that area will become over-exposed by one stop. If you close down your lens or increase your shutter speed by one stop, that area will become under-exposed by one stop.
An average tone is naturally placed into zone V. If you over-expose it by one stop, you’ll be placing it in zone VI (zone 6), causing it to render brighter than it actually is. If you under-expose it by one stop, you’ll be placing it in zone IV (zone 4) causing it to render darker than it actually is.
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0 Pure black
The relationship between the physical scene and the print is established by characteristics of the negative and the print. Exposure and development of the negative are usually determined so that a properly exposed negative will yield an acceptable print on a specific photographic paper.
The Assignment
- First- find an image by Ansel Adams an identify all of the zones.
- Then you are to go out with a grey card and a roll of Black & White Film and take portraits and landscape photos around the area. Take an overall reading from your light meter in your camera and take that photo.
- Then point your camera at a middle grey card set your exposure to that setting and then take the photo of your scene. Note if there is a difference in exposure.
- Bracket your photos at least one up and one down for each photo.
- Print a contact sheet and one 5 x 7 evenly exposed and contrasted print.
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