The Handheld Light Meter as a Creative Tool
Part 1: The Language of Exposure and the Argument for the Old Meter
In a previous installment of Behind the Film Camera, we explored what correct exposure means. To recap: correct exposure is the exposure you intentionally make so that the scene renders the way you want it to on film. If you didn’t read that article and want to, take a look here.
Today we explore the language of exposure to start building a foundation for creatively using the handheld light meter. I also explain why I think old handheld meters have advantages over modern ones.
Steps and Stops.
In the language of photography, if you add one “stop” of light from a setting, you are doubling the light to the film. A stop is relative to some starting point on your lens and camera. For example, here is how “stops” is used in the language of photography:
“Add three stops of light when you use this filter.”
“There are four stops between the shadows and the highlights in the scene.”
“I am going to add two stops of light to my meter reading because I really want to preserve shadow detail.”
In each instance, “stops” require a reference point. But what is a stop? A stop is a doubling or halving of light.
Stops and Shutter Speed
If we look at a camera’s shutter speed dial, a typical progression is from 1 second to 1/1000 of a second. On the dial, you will see something like 1, 2, 4, 8, 16, 32, 64, 125, 250, 500, and 1000. From 1 second to 1/1000 of a second, each progression halves the light going to the next faster shutter speed and doubles the light going down to the next slower shutter speed. Each shutter speed setting is one stop away from the one before or after. For example, 1/2 of a second is three stops more light than 1/16 of a second; 1 second is one stop faster than 1/2 second; 1/500 of a second is one stop more light than 1/1000, and so on.
Stops and Aperture
The aperture ring on your lens follows a similar progression of halving or doubling light. Called f/numbers, the numbers on the aperture ring have a non-intuitive progression, e.g., 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, and 22. Each setting is one stop more or less light than the setting on either side. Each step doubles or halves the light from the previous one. If your lens goes to f/1.4 and is set to that number, that aperture is wide open for your lens. To adjust one stop and halve the light passing through the aperture from f/1.4, the f/number would be 2.
Why are the numbers on the aperture ring seemingly non-intuitive? Because f/numbers are ratios of the lens focal length to the diameter of the aperture. For example, a 50mm lens with a 25mm diameter aperture is at f/2. A 50mm lens with a 2.27mm diameter aperture is at f/22. That’s why the lower f/numbers mean a larger aperture, and larger f/numbers mean a smaller aperture.
Exposure Values.
Many older and most modern handheld meters can be set to read in EVs. “EV” means exposure value. My Pentax Digital Spotmeter reads in EVs. If I point it at a surface and get a reading of 10, it tells me that the reflected light from where I am pointing the meter measures 10 EV.
But what is an EV? EV is a photography-specific term. An EV is a number that represents a combination of shutter speed and f/number, such that all combinations that yield the same exposure have the same EV. To illustrate how it works, here’s a photo from the Pentax Digital Spotmeter manual.
Note the EV scale and the 10 in the center. As you can quickly see from the dial calculator, a 10 EV equates to many f/number and shutter speed combinations: f/2.8 at 1/125, f/4 at 1/60, f/11 at 1/8, f/22 at 1/4, and so on. All those combinations are represented by an EV reading of 10. All of those combinations allow the same amount of light from the scene to reach the film.
If we used the meter and got a reading of 11 EV, and turned the EV dial to 11, we would see different combinations, such as f/8 at 1/30, f/11 at 1/15, and so on. So it goes for any EV reading you transfer to the EV dial.
The photo from the Pentax manual illustrates the basics of the exposure triangle: film sensitivity, shutter speed, and f/number. The same can be seen from the computer dial on the Gossen Luna-Pro SBC. Note the EV pointer is close to 7 and examine the corresponding f/numbers and shutter speeds.
EVs were used on many cameras in the 1960s. Hasselblad V system lenses from that decade are a good example. Get an EV reading from a meter and transfer it directly to the lens, then lock the shutter speed and aperture rings together and rotate both simultaneously to the desired combination. Quick and easy, but it didn’t stick.
Another example is the EV’s use on old film cameras in the chart found on the back of the Rolleiflex 2.8F from the 1960s. The white numbers are EV values. Look at 7 on the chart. See what I mean? The f/number and shutter speed values match the results on the Gossen meter above.
To use a chart like the one on the Rolleiflex, all you need is a meter that reads in EVs. Let’s say your meter reads 10 EV, and you are happy with that for the photograph. You could then choose f2/8 at 1/125 if you want a fast shutter and shallow depth of field, or you could go for something like f/22 at 1/2 if you are shooting a landscape and want deep depth of field. Again, all settings corresponding to 10 EV yield the same exposure on the film.
Something I haven’t mentioned yet, but you can see in the examples I have given, is that EVs, just like f/numbers and shutter speeds, are in one-stop increments. This makes measuring the range of tonal values in a scene very intuitive and easily translatable to stops.
The Argument for the Old Meter.
Modern handheld meters are great. I’ve owned a few and still have a Gossen Digisky (mainly because it also has a flash meter). They are accurate and operate by pushing a button and reading a screen. But the older meters with the dial computers have advantages, and I believe they are easier to use for creative exposure than modern meters.
One advantage is that with a glance you can see all the settings that produce the same exposure. You can see that in the photos of the Pentax and Gossen above.
Old meters are relatively inexpensive. The Pentax Digital Spotmeter is pricey at $300-$400, but the Pentax Spotmeter V can be purchased for much less and can meter just as well. The Gossen Luna-Pro SBC is an excellent reflected and incident light meter that can be found for less than $100. It’s great for extremely low light work and general-purpose photography. Compare these old meters to the newest top-end Sekonic meter at $650.
Finally, convenient zone system labels can be affixed to the dials on old meters. Some meters, like the Gossen Luna-Pro SBC, already have zone system markings on the dial.
In part 2 of this series, I will examine the 18% grey card and discuss the advantages and disadvantages of both incident and spot meters in creative exposure.
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Thanks for reading, and see you next time.
Good content Scott! Keep it up!