In part -1 of this article, we discussed about metering modes and the advantages of manual metering. In this article, I will talk about the techniques that you can use to manually meter scenes.
Any discussion around manual metering won’t be complete, without mentioning the zone system developed by Ansel Adams. In fact, a basic understanding of the zone system is essential in learning to use manual metering.
Zone system was developed by Ansel Adams in the early 50’s and is used to represent tonal values. Zone system divides the tones between total black and pure white into 10 zones. Zone 0 thus represents total black and zone 10 represents pure white (actually the paper white tone). Zone 5 represents a midtone in the scene. The standard 18% grey corresponds to zone 5 in the zone system. The zone system was originally developed for black and white prints, but is still useful in the world of color.
Now, if you look through the view finder of your digital camera, you won’t see all these 10 zones. You will see only 2 lines each to the left and right to the center line. The middle line corresponds to 18% grey or midtone and so is nothing but the zone 5. In general digital cameras can only hold details in the zone 3 to zone 7 ranges and that’s why you see only 2 zones each on either side of the middle line. In Nikon cameras, lighter tone is represented by the lines on the left and darker tone by the lines to the right of the middle tone (line). With Canon, it’s the other way, i.e. lines to the left are darker tones and lines to the right are lighter tones.
The picture below depicts the typical view finder display of a Nikon camera, generally known as the exposure indicator or metering display/indicator.
Nikon – The left most line represents zone 7 and the right most, zone 3.
Canon – The left most line represents zone 3 and the right most, zone 7.
When your camera’s meter evaluates the scene, it’s goal is to arrive at a tonal value that corresponds to the middle Grey, i.e. the middle line above. So that gives us a clue about how we should be metering the scene.
With manual metering, what we want to do is to adjust the parameters (ISO, Aperture and Shutter Speed), so that the bar indicates the correct zone that we are measuring. Let me explain, if I have a middle toned subject in the frame (18% Grey), I would dial the values to bring the exposure indicator to the middle. (What values?, aperture, shutter and ISO. I usually fix the ISO and aperture and dial the shutter to adjust the light to get proper exposure)
Metering a scene can be tricky or easy depending on the mix of lighting or objects in the scene. While an 18% grey tone in the scene is ideal for proper metering, you will in most cases find none in the scene. In such cases, I often use tones or colors that correspond or match close to 18% grey to meter the scene.
For example green grass or green leaves are 1 stop less than the mid-tone. Another way is to find dark tones or white tones in the scene and meter on that. Remember, white and black are on the extreme end of the zone system. Zone 7 is approximate white and zone 3 is approximate black. So if you see a darker shadow area (black) in the scene, you can choose it as your metering area, and dial the exposure until the spot measures a zone 3 value (or the right most line with Nikon or left most line with Canon). Or if there is a white tone in the scene, you can spot meter the tone, and dial all the way to the left (on Nikon and right on Canon) so that the camera indicator stays close to the white tone.
The real world is full of color so, here are some real world equivalents of those zone values.
1. Blue sky. The blue sky is equivalent to middle tone (Zone 5)
2. Green grass or green leaf; they are one stop less than the middle tone. Note: one stop, not one zone.
3. Your palm: Your palm is roughly 1/3 to 2/3 of a stop lighter than the middle tone.
4. Skin of a white person: one stops above the middle tone.
5. Dark Skin: Roughly 2/3 of a stop less than middle tone.
The trick here is to be able to identify each color relate to the middle tone (18%). I would highly recommend you getting familiarize with the middle tone to be able to judge the color tone better.
Now, how to meter a scene? Here is how.
• Put your camera in manual mode
• Switch to spot metering
• Select your aperture and ISO first,
• Point the camera to the scene with the spot area at the tone, that you want to meter on. Make sure to zoom in as much, to get the tone clearly isolated.
• Looking through the view finder adjust your shutter speed, until the camera metering system indicates proper exposure, i.e the exposure indicator is at the middle line.
• Lock your exposure using the exposure lock button. Recompose the scene and click away
Note down the shutter and aperture values for the current ISO. Recompose the scene, dial in the values noted in the above step and click away.
• Check your histogram to see if the exposure is correct
If you are having the camera hand held and if the shutter speed is too low to avoid any shaking or vibration, increase the ISO (under normal cases I wouldn’t go beyond 800) or decrease the aperture and try again.
Some people prefer to underexpose a scene and some others prefer to overexpose a bit. I am not going to comment on that part, as I think it’s purely a personal preference on the part of the photographer.
Let’s look at a few practical examples here.
The photo below was shot after metering the grass.
This one was taken after metering the blue sky.
This concludes this 2 part article on metering. Hopefully I was able to give you some idea on manual metering and the techniques that you can use to meter scenes for better pictures. Your comments and feedback are greatly appreciated.