Exposure and processing qusetion.

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When people say expose for the shadows and develop for the highlights, just what do they mean. If I overexpose my B+W film what do I do in the processing to account for the highlights. I am very confused. Seems like all the zone system books are over my head. Could someone please help?


-- Fount Johnson III (fj3@aol.com), May 31, 1999


"Expose for the shadows" means take a meter reading of the darkest shadow that you want to have detail in the final print, and close down about two stops.

"Develop for the highlights" means take a meter reading of the brightest highlight in the scene, and note how many stops this is away from the shadow reading. If this number is large, you will want to reduce the film development. Conversely, if this is small, then increase the film development.

(Your next question might be, "What is small, what is large?" The answer depends on the film, developer, enlarger and paper. This is why zone books are rather complicated.)

If you only overexpose by a stop or two, then don't worry about it. If the overexposure is much greater, then you may get better results by reducing the film development, but it depends on the film.

-- Alan Gibson (Alan.Gibson@technologist.com), June 01, 1999.

Zone System Simplified (extremely):

Zone I is pure black. Zone IX (nine) is pure white. Zone II is one stop lighter than Zone I, Zone III is one stop lighter than Zone II, etc.

Meter the shadows (the part you want darkest in your photograph that still has detail). Put this on Zone II (two).

Meter the highlights (the part you want lightest in your photograph and still have detail). This will fall on a higher Zone.

How does it fall? How many stops difference is it? If it is 6 stops difference, then it would be on Zone XIII (eight).

Your exposure is Zone V (five) but some people expose for Zone VI (six).

If the highlight is Zone VI or VII then it might not be white enough for you, so you'll need to increase the contrast in either the negative or the print. An increase in the contrast is a REDUCTION in the range of the negative.

If the highlight is in Zone IX or higher, you'll need to reduce the contrast in the negative or the print. A reduction in the contrast is an INCREASE in the range of the negative.

How do you reduce / increase the contrast in the negative? By developing for less time, you reduce the range or increase the contrast, by developing for more time, you increase the range or reduce the contrast.

How do you reduce / increase the contrast in the print? By using different grades of paper (or different filters on Variable Contrast paper).

That's it in a nutshell. All the rest is embellishments and how-to's.

Hope this helps, Andy Hughes http://darkroomsource.com/ dedicated to darkrooms

-- Andy Hughes (andy@darkroomsource.com), June 01, 1999.

By exposing for the shadows you guarentee detail in the dark areas, but you are right you are in overexposing the highlights.

Just reduce the developement.

The shadow areas, having fewer grains of exopsed silver, don't take too much time to be fully developed. They develope early on and basically finish and sit around. The more exposed areas have a larger volume of exposed silver to be developed. They need extra time to develope to completion. Reduce the time in the developer and the less volume of exposed silver gets built up. Thus less highlight density and contrast. Usual amount is -20% for a one stop reduction, -15% for T grain films. When in doubt overexpose and underdevelope !

Camera exposure for the shadows. Develope (to control) the highlights.

-- Peter Thoshinsky (camerabug1@msn.com), June 07, 1999.

.......sorry should have read: "By exposing for the shadows you guarentee detail in the dark areas, but you are right, you are in FACT overexposing the highlights".

-- Peter Thoshinsky (camerabug1@msn.com), June 07, 1999.

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