"Zone VII," Weekly Photography Assignment for 22 - 28 February 2010

[keithsnell]

We've had several "thematic" assignments recently, so now its time to get back to one that is a little more technical.  The title for this week's assignment is "Zone VII."  This term comes from the Zone System method of controlling exposure, as taught by Ansel Adams.  Many students of Ansel Adams will say that you can't talk about the Zone System without including the darkroom or "development" aspects, so for the purpose of this assignment we'll call our reference a "modified zone system."

As I mention in the "Understanding and Controlling Exposure" tutorial on the front page of the site, very few digital sensors have the ability to capture the entire range of light values that are present in a normal sunlit scene.  If a camera manufacturer follows the ISO standards for calibrating the output from their sensor, then there is a theoretical limit of just less than 3 stops above mid-tone before the sensor saturates at “pure white.”  (Fuji sensors are an exception to this rule, since they use two photo-sensitive areas per pixel in order to extend the highlight range.)

The “zones” defined below segment the light levels in a typical sunlit scene into 10 regions.  Since our digital camera can’t correctly record all 10 zones, we need to make a conscious decision on what tones in the scene we will expose to fall within the limited tonal range of our camera’s sensor.

                                          Zone I        Black without any texture
                                          Zone II       Black with slight suggestion of tonality
                                          Zone III      Darkest areas that still retains visible detail
                                          Zone IV      Average shadows in landscapes/portraits
                                          Zone V       Middle Gray - 18% gray card
                                          Zone VI      Average Caucasian skin
                                          Zone VII     Lightest areas that retain visible detail
                                          Zone VIII    White areas with slightly visible textures
                                          Zone IX      Glaring white surfaces - Highlights
                                          Zone X       A light source (maximum white)

"Zone VII" based exposure techniques are used when photographing a high-contrast scene that exceeds the range of your camera's sensor, or might otherwise fool your exposure meter.  

To determine the correct Zone VII exposure for a scene set your camera to manual exposure and spot metering and meter on the brightest part of the scene where you want to maintain detail, such as a textured area of snow, then set your exposure so the exposure scale meters this area as Zone VII, or 2 stops above mid-tone.  Simple as that!

Anybody have any textured snow they can photograph?

For this week's assignment, you should expose your image using manual exposure and spot metering on a "Zone VII" area of your scene.  You will know you were successful if that area of the scene is rendered as bright as possible while still retaining visible detail or texture.  Please upload your images to the "Zone VII" album in the Weekly Assignments category of the Gallery no-later-than midnight, Mountain Time (GMT -07:00) on Sunday, 28 February 2010.

I'll look forward to seeing your images.

Keith

[burzilai]

Hi Keith,
I have some questions,   we are not limited to just  a snow scene for this assignment right? does the subject needs to be something of a light or white color ( like snow) in order to correctly place them in zone VII?  let's say I have a landscape I want to photograph, should I meter the snow capped tips and then adjust to 2+ from these and take the pic.? what about the other darker areas?  do i have to meter the other parts of the landscape and take a different picture with a different exposure?  I tried taking a pic of snow capped Mt but it kinda turned very light, there's some detail but it was light I wasn't sure I did it right.  Also, hOw do I also check if did it right, aside from a very bright snow  result, in the histogram  where should I see the graph to indicate that I indeed, exposed that image in zone VII?  Can I place other colors in zone VII? light yellow? light tan?  anything light, or is it only white color?  Also, in adjusting the exposure, is it the same to use Exposure compensation function to acheive a +2 /zone VII? or not?
Also, the zone system is it only applicable to a landscape sunlit scene? how about a sun shining through a window? can I use that light source and spot meter my subject?
I havent photographed anything yet, I want to understand a little it more about the zone VII exposure before I take photos, so that I can somehow apply it, Im not sure if Im doing it right. Any enlightenment will be appreciated
Thank You
Sheila  

[keithsnell]

Hi Keith,
I have some questions,   we are not limited to just  a snow scene for this assignment right? does the subject needs to be something of a light or white color ( like snow) in order to correctly place them in zone VII?  let's say I have a landscape I want to photograph, should I meter the snow capped tips and then adjust to 2+ from these and take the pic.? what about the other darker areas?  do i have to meter the other parts of the landscape and take a different picture with a different exposure?  I tried taking a pic of snow capped Mt but it kinda turned very light, there's some detail but it was light I wasn't sure I did it right.  Also, hOw do I also check if did it right, aside from a very bright snow  result, in the histogram  where should I see the graph to indicate that I indeed, exposed that image in zone VII?  Can I place other colors in zone VII? light yellow? light tan?  anything light, or is it only white color?  Also, in adjusting the exposure, is it the same to use Exposure compensation function to acheive a +2 /zone VII? or not?
Also, the zone system is it only applicable to a landscape sunlit scene? how about a sun shining through a window? can I use that light source and spot meter my subject?
I havent photographed anything yet, I want to understand a little it more about the zone VII exposure before I take photos, so that I can somehow apply it, Im not sure if Im doing it right. Any enlightenment will be appreciated
Thank You
Sheila  

Hi Sheila,

Thank you very much for asking.  Correct, this assignment is not limited to just a snow scene.  I just used that as an example.  The subject should be of a light color (or white) in order to be correctly placed in Zone VII.  In general, a Zone VII exposure should expose the area of the subject you are metering as white (or a very light color), but with visible detail.  

I've included an example of a white towel exposed at +2 EV so that you can see the level of detail visible in a "typical" Zone VII area of a scene.  (This image is a crop of a zoomed in portion of the towel so that you can see the detail.)  The level of detail will vary slightly depending on the scene.

White Towel exposed for a Zone VII Exposure (spot metered at +2EV)

I've also included the histogram from the white towel test.  You can see that the right edge of the histogram just touches the right side of the scale, and that the "mean" of the histogram is around 241 (of 255).  Does this help?  (Please note that if your scene includes darker areas, the histogram will also show those areas to the left of the "Zone VII" areas.  The histogram I have included as an example is just an approximation of what a "typical" Zone VII area will look like in your histogram.)

Histogram of White Towel exposed for a Zone VII Exposure

Yes, you are correct that using +2 exposure compensation (and spot meter) should provide essentially the same results as using spot meter in manual exposure mode and setting your exposure to read +2.0 on the exposure scale.  One reason to use manual exposure is because you can point your metering spot on the Zone VII area of the scene, meter and set your exposure, and then recompose your scene without worrying about your exposure changing.  If you use exposure compensation, your exposure will be correct for a Zone VII exposure when you have your metering spot on the lightest areas of the scene where you want to retain detail; however as soon as you move your camera to recompose the scene, your exposure will change.  Does this make sense?  Using manual exposure allows you to set a Zone VII exposure and keep it set, and also gives you the flexibility to meter on other areas in the scene to see how dark they will be in relation to a normal exposure.

The Zone System applies best to a sunlit scene; however, you can use the same techniques if you are trying to retain detail in the sunlit portion of a scene through a window.  The difference in this situation will be that the interior will be much dimmer, and therefore your normal mid-tones will fall below Zone V.  You can use a brightness adjustment in your raw processor to bring the mid-tones up to where you want them.  It is much easier to adjust the mid-tones in post processing (within reason) than it is to try to recover blown highlights.

[burzilai]

Thanks so much Keith, that was well explained, particularly why we should shoot in manual vs using Exposure compensation. Although like the others, I'm still struggling in  finding an appropriate subject. I have turned my house inside out and there were only 2 things I found that may be suitable. quick question though, when you take a "high key" photo is that considered  like a zone VII or VIII?
thanks again

[keithsnell]

A "high key" image would typically contain tones in zones VI through VIII, so yes, you could say that a high key image is very similar to a Zone VII image.  This assignment was emphasizing an exposure technique more than an image style; however, several of the submissions could indeed be categorized as "high key."

Yes, the snow I expected didn't come, so I too am struggling to find an appropriate subject.  Hopefully we'll all surprise ourselves.  :-)

Keith

[burzilai]

Keith, here are other shots I took yesterday but didn't pick for submission: files attached... I can't seem to insert it in the msg body,..how do I insert pics next time?

[keithsnell]

Hi Sheila,

First the easy answer.  To insert the images into the message body, just copy the "link" at the bottom of the "file information" section in the Gallery, and then paste that link into the message body where you want the image to appear.

The image of the angel you attached gives us a much better idea of the lighting on the angel.  I agree with your earlier comment that you should have probably metered on the light area on the angel's cheek.  I think if you would have metered there, you could have avoided the "hot spots" and all the other exposures could have been adjusted in in post processing.  (The shadows might have been a little darker, but those are relatively easy to adjust in post processing.)

Keith

[keithsnell]

I wanted to show one more example of an image that benefited from a Zone VII exposure technique.  This image was shot with a large format camera on Velvia transparency film, but the same principles apply.

If I had taken this image with my 35mm camera set on evaluative or matrix metering, the snow on the mountains would have been overexposed and "blown out" with no detail. (Because the preponderance of the scene was much darker, it would have picked an "average" exposure that would have resulted in the snow being overexposed.)   In order to prevent this from happening, I used spot metering on the brightest areas of snow on the mountain, set the exposure manually to +2.0 EV, and then transfered those settings to my large format camera to take the image.  After scanning the image from transparency I made a slight curves adjustment to lighten the mid-tones and corrected for vignetting in Photoshop.  (This is a low quality JPEG copy of the original, but I think it is good enough to illustrate the point.)