July 2009 Newsletter (Simplify Zone System)
Hello Raw Shooters
The new high end digital SLRs have more mega pixels and 14 bit Raw files, which can create a huge workload on computers when handling these very large files. Thanks to our fast and easy to use website, more pro photographers come aboard every day! Our state-of-the-art Mac pro towers handle these massive files with ease and allow us to give you quick turnaround time.
As an example if you shoot with Nikon D3X,Nikon D3, Nikon D700, Canon EOS 1Ds, Canon 5D MKII, Sony A900..... with 14 bit Raw capture, you will end up with file sizes ranging from 16 to 50 MB! Imagine that in a typical wedding you shoot 500 images; the average total file size for a wedding will be around 2-3GB! When editing on your computer, you’ll need at least 4-6 GB of Ram and a very fast processor. Thanks to our exclusive services, you don’t need to worry about the speed and amount of RAM in your computers. Just get to your FTP account and upload them to us. In 4 to 6 business days log in to your FTP account and download the edited images! It is that simple and fast!
Are you one of many photographers who think the Zone system is only for developing negatives and prints? In this series of articles I am going to show you how to use the Zone system for exposure. When using the Exposure compensation in our cameras the Zone System helps us calculate exactly how many stops we need to compensate. For additional reading there are several books about Zone System. The Confused Photographer's Guide to Photographic Exposure and the Simplified Zone System by Bahman Farzad is a good source and explains the Zone system very efficiently.
So go ahead and upgrade to a better camera and provide the best possible images to your clients. You don’t need to worry about the file size anymore!
Now let’s get to our monthly tip:
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Exposure compensation and Zone System
(Part 2)
Now that we learned about the Zone system lets talk a little more about how to find the zone system in our subject and understanding the Histogram.
Here is the histogram for an 18% Gray card
When working with the Zone System, you may find it helpful to center Zone V in the camera's histogram. To do so, you need to calibrate your exposure meter to match the camera's sensor. Meter off a uniform gray card and process the RAW file with all sliders in their neutral positions. Look at the histogram of the exposure and notice how much the mean value deviates from middle gray (126). This tells you the exact EV amount you need to add to your meter's reading. You can either add the EV figure to the meter's reading, or you can adjust the ISO setting on your meter to compensate for the offset and your camera's real ISO. For instance, if you find that you need to add +0.5 EV, set your exposure meter to ISO 75 when your camera is set to ISO 100.
The two images below show how the Zone Scale applies to photographs. Below each image is its histogram. The histogram shows how the tones in the image maps onto the Zone Scale.
The image on the left, showing jazz drummer Billy Cobham in action, is a photograph where the tonal range is spread fairly evenly across all nine zones. There is just a slight peak in Zone I (dark background, black hair and beard). The drummers' forehead lies within Zone V, which is the Zone most photographers would want to use for dark skin, and the rest of the tones in the photograph spread out around this.
In the image on the right most of the data is in the low (Zone I, II, III) and high (Zone VII, VIII, IX) tones. Almost no area of the subject lies in the mid tones. This is a typical high contrast image, which is characterized by a U-shaped histogram.
In low contrast images, the peak in the histogram will be in the mid-tones. There are also tonal styles called "high key" and "low key", where the histograms peak will be in the high or low tone area of the histogram, respectively.
For the Zone System, light measurements are always done with a spot meter, preferably one with a one degree coverage. A spot meter is essential because you will be measuring specific portions of the scene, and then "placing them" in a specific zone. It is this placement, and not the meter's reading, that determines exposure.
With the Zone System, you will deliberately measure different parts of the scene and noting how they differ. The spot meter reading (after adjusting the meter's ISO to offset the K factor and your camera's real ISO) will always report the exposure that will render that part of the scene as middle gray (Zone V). However, we do not always want things to appear as middle gray. Therefore, we need to determine how we want the subject to appear in the final print, i.e. to decide what zone the object should ideally appear in.
Ansel Adams called this process "visualization". After doing a visualization of the appropriate zone, we "place" the subject in the desired zone by modifying exposure up or down the scale to move the object from the measured to the desired zone. For instance, to place an object metered in Zone V in Zone VI, we use a +1 EV exposure adjustment.
When adjusting exposure, you are determining the tone values an object will have in photographic print independent of what tone values it has in real life. An experienced Zone System practitioner mentally visualizes the change in an object's tone values as he or she moves it up and down the zone scale at the time of exposure.
Examples
It is simpler to do this than to explain it, and some examples will make this clear.
Let us say we want to do a studio portrait of someone with light skin. We shall place the lit side of the subject's face (the most important portion of a portrait) in Zone VI. First, meter the face. What the meter gives you is the setting for a Zone V face. You will have to give the face more exposure than indicated by the meter (more light on the sensor) to place it in Zone VI. Opening the lens one f-stop (+1 EV) from the metered exposure will have this effect.
Now, let us move on to photographing a tanned skin tone. It's not black, but it's dark. Maybe you would like it to appear in Zone III in the final print. Again, your spot meter indicates exposure for Zone V. By closing down two f-stops (-2 EV), the subject’s skin tone will be placed in Zone III.
Summary:
Three things you need to know to use the Zone System to place single objects are:
1. The Zone scale is a progressive series of tone values. Each value is the equivalent of one full f-stop or one EV step.
2. The spot meter provides exposure readings for Zone V, giving you a correct exposure for a known Zone.
3. By adjusting exposure you can place the object in any Zone. On a calibrated monitor, and in the final print, the object will assume the tone value of the Zone in which it is placed.
When learning the Zone System, it may be a good idea to practice metering all sorts of objects, deciding what Zone the object should be placed in, and then doing the necessary mental adjustment to effect this placement, i.e. a visualization of the tone shift as it will appear on a calibrated monitor and in the final print.
With a digital camera, experimenting is much cheaper than using film, so you should practice this and evaluate the results on your computer's monitor until using metered values to effect Zone placement becomes second nature for you.
Stay tune for part 3 of Zone System in next month newsletter.
Have a great month!
That’s all for this month. See you in Aygust with part III of this exciting tip.
Ted and Omnilargess Team
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