Sony Zone System... GUEST ARTICLE
The ZONE SYSTEM is an idea first formulated by Ansel Adams, Fred Archer and Minor White in the early 1940's and brought out in a book of that name authored by Minor White.
It observed that B&W images could be thought of as having zones of tonality --each one stop apart-- that could be manipulated in lighting, exposure, processing and printing in ways that achieved the desired intention of the photographer.
Photographer Shay Stephens updates the concept and brings a new kind of awareness to users of the DSC-F717 with its live histogram display.
The Digital Zone System
By Shay Stephens
Layout by Peter iNova
You may have heard of the zone system and spot metering and histograms, but what does it all mean, and how do you use it?
The spot meter:
This little gem allows you to determine the brightness of a small circular area the diameter of the cross hairs. However it does not tell you what exposure you need to use, the reading must be interpreted by the photographer.
The meter will tell you how close to "middle toned" the area under the cross hairs is. If you aim the cross hairs at a gray card (which is exactly middle toned) the meter should read "0EV" letting you know that the spot meter believes it sees something that is middle toned.
If you are aimed at a gray card, and the meter does not read 0EV, you need to adjust the exposure until the meter reading does say 0EV.
What if, however, we aim the spot meter over a piece of white paper instead of a gray card?
Since white paper is 2 stops brighter than a gray card (or +2EV brighter) the meter should read +2EV. If the meter reads, for example +1.3EV we know we need to adjust the exposure time until the meter reads +2EV.
This will make the exposure longer, resulting in a brighter picture that will be properly exposed for the white of the paper. Which brings us to...
The zone system (for exposure):
The zone system is simply a way to assign exposures to familiar things with a known brightness. We have already covered two examples.
A gray card being middle toned and showing up in the meter as 0EV, and a white piece of paper, which will show up as +2EV.
But what about other items? And how does the zone system apply to them?
The zone system is divided up into 10 zones.
From zone 0 to zone 9:
Zone 0 = -5 EV = Pure black no detail
Zone 1 = -4 EV = black, only a hint of detail
Zone 2 = -3 EV = black with some details visible
Zone 3 = -2 EV = dark but with full detail visible
Zone 4 = -1 EV = dark toned with full details visible
Zone 5 = 0 EV = middle toned, full details visible
Zone 6 = +1 EV = light toned with full details visible
Zone 7 = +2 EV = White with some detail visible
Zone 8 = +3 EV = White with a hint of detail
Zone 9 = +4 EV = Pure white no detail
The image above shows the same piece of fabric at different exposures. Each exposure is one full EV/stop from the next.
Now that we know how the zones of the zone system are divided up, let's assign some familiar things we might see in a typical scene to the zones:
Zone 0 = -5 EV
Pure black, darkest shadows, deep cracks, black nighttime skies
Zone 1 = -4 EV
very dark shadows
Zone 2 = -3 EV
dark shadows, black cloth, black plastic, black/dark brown hair
Zone 3 = -2 EV
Brown hair, blue sky, dark green leaves, shadowed dark skin.
Zone 4 = -1 EV
Dark skin (generally)
Zone 5 = 0 EV
Gray card, stone washed blue jeans, shadow on light skin
Zone 6 = +1 EV
Zone 7 = +2 EV
Paper, snow, white sand, white walls, white t-shirts
Zone 8 = +3 EV
An overexposed window, pure white backgrounds
Zone 9 = +4 EV
Specular reflections, lights
So if we see something in the scene that has a known brightness, we can spot meter off that object to get an accurate exposure.
For example, we are out with some friends, and they stand next to a fountain. One of them is wearing a white t-shirt. You want that t-shirt to look a bright clean white, so you meter off the shirt, set the exposure until the meter reading just shows +2EV and snap the picture.
You can be very confident that the exposure will come out good.
But now we have an additional tool to help us with exposures, we have...
The histogram (in camera or in PS):
The histogram is a graphical representation of the distribution of tones in the scene. Far left represents pure black, and far right represents pure white.
The fabric samples shown above have a distinctive histogram (right).
You can see that each zone has it's own corresponding peak in the histogram.
Now lets take a photo using the spot meter and the zone system and then analyze the photos exposure using the histogram.
Here I have a pair of stone washed blue jeans and a t-shirt. I spot metered off the t-shirt and set the exposure so that the meter read +2EV (zone 7) and then took the picture (left).
The photo's exposure looks just the way it did in real life, this is a good sign.
Now lets look at the histogram and see how the image data is distributed:
You can see the peak on the right hand side corresponds to the +2EV and this would represent the t-shirt in the photo.
Look at the wide peak centered on the 0EV mark.
That would be the stone washed jeans, but what is that smaller peak just to the left? We can see it is about -.5EV, and you will also notice there is a dark "Wrangler" label visible on the jeans.
The small peak represents that small darker label, and we now know how bright it is compared to both the blue jeans and the t-shirt. We can also see that the scene was metered accurately and all we did was apply the zone system using the spot meter in determining what our exposure was going to be.
The histogram lets us analyze an image after we have taken it to see how well the tones in the exposure match the actual tones in the scene.
As you become more familiar using the histogram, you will be able to quickly determine if the image has the right exposure and the tones are distributed the way they should while viewing the live histogram on the camera.
In practice, all of this works quickly and accurately once you get the hang of it. If you master the techniques, your exposures and productivity will thank you for it.
This article ran originally as a post to the DPReview Sony Talk Forum. Reprinted with permission.
Shay's galleries will inspire 707/717 owners. Check them out:
More will be here as the Sony Zone pages evolve.
PS: As experience grows with these cameras, so will this review and the Sony eBook. Available now on the order page.
Article © 2002 by Shay Stephens. All rights reserved. Images and screen captures by Shay Stephens.
Site © 2003 Peter iNova. All rights reserved. Do not replicate or link to images without permission. All photos by Peter iNova.