View Full Version : how does the zone ruler work

26-08-2011, 12:02am
HI again!

Once again I would appreciate the help of the awesome members of AP. Think my brain is about to explode trying to understand Dynamic Range and The Zone System. The real problem I think is I dont know what to do with the info and how it helps?
I think if I understand that then I might be able to get my head around it all.


26-08-2011, 7:09am
The Zone system was originally developed by Ansel Adams and Fred Archer for determining a good exposure for film. It can be used for digital camera, but as digital sensors have a different dynamic range (levels from the brightest to the darkest they can capture) it needs tweaking for digital use.

However the basic concept is about ensuring you get an accurate exposure when you press your shutter button.

The Zone System is about exposure and metering your scene. Now first up, the metering system in your camera is kinda dumb. All it does is measure the light levels in your scene. It 'thinks' your scene is perfect and that the sensor is able to capture all the really bright bits and the darkest blacks, but it does this by assuming the average tone in your scene is mid-grey. So say you wanted to photograph a scene filled with snow, there is a chance your camera's meter will 'think' the white show is actually mid-grey, and thus your photo will be incorrectly exposed.

Now this is where the zone system comes in, and YOU as the photographer being able to see that the snow isn't mid-grey, and thus YOU making the camera work and get a correctly exposed result.

However, digital cameras have come a long way and matrix metering (metering multiple points in a scene and getting an average) has overcome the need for most photographers even needing to understand the zone system, as multi-point metering is in fact an electronic version of the zone system.

The zone system is a method of determining the tones (bright points, dark points, and everything in between) to ensure you take your photo with the correct settings to ensure an optimally exposed result (no blown highlights or not underexposed and dark). This was particularly important when film was reigning supreme as film and the processing of it, was much more expensive than taking a digital photo.

Low values
Zone 0 Complete lack of density in the negative image, other than film base density plus fog. Total black in the print.
Zone 1 Effective threshold. First step above complete black in the print. Slight tonality, but no texture. Zone 2 First suggestion of texture. Deep tonalities, representing the darkest part of the image in which some detail is required. Zone 3 Average dark materials. Low values showing adequate texture. Middle values
Zone 4 Average dark foliage. Dark stone. Landscape shadow. Recommended shadow value for portraits in sunlight. Zone 5 Clear north sky (panchromatic rendering). Dark skin. Gray stone. Average weathered wood. Middle gray (18% reflectance). Zone 6 Average Caucasian skin value. Light stone. Shadows in snow in sunlit snowscapes. High values
Zone 7 Very light skin. Light gray objects. Average snow with acute side lighting. Zone 8 Whites with textures and delicate values (not blank whites). Snow in full shade. Highlights on Caucasian skin. Zone 9 Glaring white surfaces. Snow in flat sunlight. White without texture. (The only subjects higher than Zone 9 would be light sources; they would be rendered as the maximum white value of the paper surface.
The idea is that you take a meter reading of various points of your scene and you adjust your exposure to make the result what you want.

It probably isn't a beginners concept, and it is most relevant to those shooting film (I use a hand-held light meter when shooting film) to determine my exposures, but I use the metering system inside my digital camera when using digital. Digital also has the benefit of the LCD and histogram, so you can take a shot, review it, adjust your settings and get some damn good results. Film doesn't allow instant replay, so you have to rely on ensuring your film is going to be exposed well, by taking readings with a light meter or using the zone system and setting your camera up to get a correctly exposed shot, straight up..otherwise you waste a lot of film and a lot of money.

26-08-2011, 11:43am
I have created a zone ruler for both of my Pentax DSLRs.It is very handy for working out the Dynamic range of your camera.Knowing how many stops either side of middle zone is usable.Its a very handy thing to know.

26-08-2011, 5:24pm
Thanks Rick...
Ok so to use my zone ruler would I first have to do a grey card test to get my meter readings for correct exposure being zone 5, and then from there is it just purley visualisation, guessing and experience as to what zone is suitable for that specific shot?
Is each zone 1 stop exactly?

26-08-2011, 5:58pm
Manda, what I think is that you are getting way ahead of yourself as a beginner, to be even contemplating the Zone System. You and your camera are quite capable of getting well exposed photos without the need to spend time working out if you are in a certain Zone. At this time in your photographic learnings, you should be practicing as much as possible and using your histogram to determine if you shot is over or under exposed and adjust settings based on that. You will find doing that will result in you improving, rather than learning about the Zone System.

But yes, if you aim to get an exposure that hits at about mid-grey (zone 5) then you will find you generally get a well exposed photo, as your digital camera sensor is probably capable of 7-9 stops, so hitting mid-grey will result in a photo that is well exposed within the limitations of your sensor.

26-08-2011, 9:43pm
I think your right Rick it really does seem very advanced stuff for a newbie...But I dont have much choice as I am doing a on line course with The Photography Institute. Mod 3 is all about metering and exposure and this is where the zone ruler comes into play. We are graded on it. Have to say the modules dont go into great depth so I am finding myself doing a awful lot of my own research.
In saying this AP has been a great help and I am glad to have found this forum. So any bit of insight is greatly appreciated.