Seminar 2 Debrief
We had a great session today, in Conquering the Camera Seminar 2. I saw a few light bulbs go off which was really cool to see. We went over camera mechanics again just to be sure, and briefly looked at images submitted from Assignments 1,2 and 3. We then looked at light metering, and started looking at how to assess light out there in the big wide world.
The Zone System
The Zone System sounds theoretical and old fashioned and probably has nothing to do with modern funky cameras that will do all the thinking for you…but think again…stick with me this is going somewhere. If you want to understand how to achieve correct exposure, then you will need to switch your camera setting so you can see the histogram reading alongside the thumbnail version of your images that appears on the viewing screen of your camera. The histogram gives you a measurable description of your exposure in the form of a graph and it’s based on the Zone System.
I love the Zone System:
a) because it was invented by Ansel Adams, we love Ansel because he’s arguably the grandfather of photography and invented this simple system along with his mate Fred Archer back in the 1940’s,
b) because it’s a super simple way to understand how you can assess the scene in front of you and achieve a correct exposure
(graph sourced from photo.club.kmu.edu.tw/; image Beth Jennings Photography)
The Zone System is an exact approach to assessing light and then making an exposure accordingly. The original numbering was given in Roman numerals, but for ease of reading here I’m going to describe them as Arabic 0-10.
As photographers we can see that the scene before us reflects light. Some things reflect very little light, like the shadows underneath a bush, while other things reflect lots of light, like a white wall. The easiest thing you can do is look at a subject and assess it in terms of how much light is reflecting off that subject – and then transfer that assessment over to the Zone System. This is the simple part, the Zone System ranges from number 0, or Zone 0, the darkest black, to Zone 10, the brightest white, with everything neatly placed in between. These Zones double and halve in value, which we refer to as a ‘stop’, just like our ISO, Aperture and Shutter Speed. The majority of things we aim to photograph like trees, people, buildings etc, fall in and around Zone 5, which we call midtone grey.
Now, whilst we as human beings can assess a scene, and see roughly where our various subjects might fall within the Zone System, our cameras cannot. And, given that most subjects we want to photograph fall in and around Zone 5, or midtone grey, well then it makes sense that our cameras are designed to meter the light reflecting from our subject, and to put the correct exposure, at midtone grey. So, in my picture above of Ben and Doug, we have dark shadows (Zone 0) and bright white walls (Zone 10), and our human subjects falling in and around Zone 5, or midtone grey. To be precise, Doug’s arms pretty much fall bang on midtone grey (look at his arm and take a mental picture of how dark that grey is, then assess it against the Zone 5 grey on the left). So if we took a meter reading for Doug’s arm area, accepted the reading and didn’t change it, then stepped back to frame the shot, exposed the shot, well then all of the elements of this picture would fall where they belong in relationship to the Zone System.
So back to Ansel…he was a genuis at using this simple system to its full potential. And by that I mean, he’d assess his scene, meter it according to Zone 5, make the correct exposure, and then work that picture to a piece of fine art by moulding and massaging those tones in the darkroom…in modern terms we’d say of course in Adobe Lightroom or Photoshop or some other image processor software. The trick is to remember that when we made the switch to digital, it had to be easy, and so camera manufacturers transferred all that Zone System talk straight across. So if you think you’ve escaped the old school and now ought to make a decent picture just because you have a decent digital SLR, think again, because the principles are all the same, we just now use a sensor rather than a film emulsion…
The beauty of digital now is that we can set the camera so that a small thumbnail of the image appears along with the histogram on the viewing screen. Flip Ansel’s Zone System on its side, so you have Zone 0 blackest black at the left running across to Zone 10 brightest white:
image courtesy of Photo Answers
On the histogram at the top, the height of the black (let’s call it a mountain) depicts the richest level of exposure. If you let your eye jump between this graph and back up to the horizontal Zone chart above it, you can see how the midtones directly correlate with Zone 5. So lots of black in the middle of the histogram, a peak like a mountain in the middle, means we’ve exposed the midtone area, Zone 5, and around it, very well. We have rich detail, and this is correctly exposed, with medium to low exposure into the blacks and up to the whites. The lower two graphs show you how an image looks overexposed (lots exposure over to the right), and underexposed (the mountain is leaning off to the left).
When you’re making a photograph I recommend that you aim to have your histogram look like the above entitled ‘Average Histogram’. Ultimately, to conquer your camera and get decently exposed pictures, you can do this, and totally bypass all this Zone System talk. The reason I have included all this information behind it, is because I think it’s important we understand how this graph comes to be…because once you understand the rules, you can then break them…ha ha!…more on that later…
Right soldiers, your mission should you choose to accept it, is to make a photograph whereby you have correct exposure. During this exercise you’ll see how you can’t rely on the camera’s light meter to always do the work for you. When we take a photograph, as a starting rule the order of steps to to take are:
a) assess the light
b) select your ISO
c) decide on a shutter speed
d) establish correct exposure using the camera’s built in light meter reading
e) set the camera to the recommended aperture
f) take the picture…and then see how your histogram is looking
Here’s what you need to do:
1. Go outside in late afternoon sun, in my pano here above I picked a random oval this afternoon with my designated subject, Julie. For this type of light I will work with ISO 400 but you can bump it up to 800 as the light is dropping off, the trade off of course is you may get some digital noise.
2. I knew I’d be shooting a person, and wanted to arrest all movement, so I selected shutter speed 1/400, something fast anyway.
3. In my scene here I can see the primary light source, the sun, off to my left. Behind Julie is a nicely illuminated, evenly lit bush and trees, no nasty bright spots or deep shadows, just even light. Put your person in a shaded area like this. To add to my challenge Julie is wearing a white coat.
4. Aim your camera straight at your subject, and take a reading. My camera tells me that if I use ISO 400, at 1/400 second, that I will need to use F4.5. Now, Jules is wearing a white coat and it is predominant in the frame. If we remember back to our Zone System, this coat probably falls into the Zone 7 area, it’s bright, 2 stops brighter than Zone 5. But my camera doesn’t know that, it only makes readings for midtone grey, midtone grey, midtone grey. We take the photo and the result is flat and muddy…it’s underexposed. Why? Because the light meter took a midtone grey reading as always, and it gave me a midtone grey, Zone 5 reading for a subject that in fact should be recorded as a Zone 7 tone.
Oh dear, it’s been recorded as a Zone 5 subject = underexposed and muddy.
5. Relying on the camera to achieve a correct exposure is a furfy. It is only capable of giving us a reading for midtone grey…so how do we fix my picture of Jules? What happens if I meter an subject within this area, which itself is a midtone subject. Let’s aim it down at the ground, at green grass, and take another reading:
To correctly expose this general area and to place the midtones where they belong on the histogram, we need to actually allow more light to the lens – 2 stops more to be exact. So in my case I’ve slowed the shutter speed and now use 1/100 second. Keep this new reading, and take your camera back to your subject…back to Jules…
et voila! Jules no longer looks muddy, her coat is bright and just holding detail, her skin is more luminous, the trees and grass in the background are tonally where they should be, recorded at Zone 5 and her curls are dark and shadowy with still some detail held, somewhere around Zone 2. Let’s look at that same picture now with the histogram:
Green: The dark curls are down around Zone 2.
Yellow: The yellow shows the midtone subject (grass and trees) as they appear on the histogram.
Red: Jules’ skin tone is a bit brighter than Zone 5, it’s up a bit in Zone 6.
Purple: The white coat that dominated the frame and threw off the light meter, is now correctly exposed and sitting nicely in Zone 7-8
Remember that while your camera will always meter for midtone grey, it is not always reliable if the scene you meter has something in it that is not a mid tone grey subject. Unlike your camera, you can see all the tones, so look for midtone grey, and meter for that if you have a wild crazy scene tonally speaking, as I did here with Julie’s coat.
This is a fairly chunky post, I know, but it is a step up from auto and requires you to take into account the way a camera is designed to interpret light. If you learn this, along with the camera mechanics, you’ll be well on your way to conquering your camera, I promise!
Good luck! And please drop in your comments and questions here for the benefit of everyone.
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