The Exposure Triangle
In a nutshell, I already understood the three elements of the “exposure triangle”: shutter speed, aperture, and film sensitivity.
Looking at my Nikon F camera and its 50mm f/1.4 lens, though, I saw what felt like a daunting pair of controls for setting shutter speed and aperture. In addition to “T” and “B,” my shutter speed dial included a range of selections from 1 sec. to 1/1000 sec. On my lens was a dial with more settings ranging from f/1.4 to f/16. As one would typically find in the film photography world, each progressed in full-stop increments.
I understood the reciprocity between shutter speed and aperture. Making the shutter speed slower by one stop, for instance, is the same as increasing aperture by one stop. The reverse is true, too. I also understood the effect of shutter speed on freezing moving subjects and the effect of aperture on depth of field.
What I didn’t fully understand, however, was what combination of shutter speed and aperture settings were appropriate for a given scenario in terms of making the best exposure.
Further compounding matters was the third element in the exposure triangle: film sensitivity or speed. Here, too, I understood the basics. Those films with an ASA ratting of 100 were the least sensitive or slowest yet the least grainy. I also knew that as film speeds increased in full-stop increments to 200, 400, 800, 1600, and even 3200, they become more sensitive at the cost of the image appearing grainier. And I knew that going from an ASA rating of 100 to 200, for instance, is the equivalent of increasing light by one stop either by lengthening exposure time or widening aperture.
Film speed seemed like a further complication in what felt like an already complicated problem.
Primed with my existing base of knowledge, I did a bit of research. I searched for answers on how to shoot without a light meter and came up with lots of hits.
Sunny 16 Rule
The Sunny 16 Rule is the classic starting point. I knew about it even before I undertook an effort to develop my understanding of how to shoot without a light meter, but I had never really practiced it.
Basically, the Sunny 16 Rule dictates that, under clear and bright sunny skies, the photographer should set the camera’s aperture to f/16 and its shutter speed to the fractional inverse of ISO.
If one is shooting with ASA 100 film, for instance, the shutter speed would be set to 1/100 sec. If only full-stop shutter speeds are available, the photographer should go for the shutter speed closest to that. For ASA 100, that would be 1/125 sec. on cameras with modern shutter speed increments.
Under different conditions with less light, the Sunny 16 Rule calls for some adjustments. If you are shooting under partly cloudy or hazy skies, open your aperture by one stop to f/11. If you’re under bright overcast, use f/8. If stormy clouds loom, use f/5.6. If you’re in open shade under clear skies, use f/4.
Outdoor 8 Rule
In a February 2017 posting on his website, film camera enthusiast Mike Eckman suggested a more general guideline: set your shutter to the inverse of the ASA film speed number and your aperture to f/8. Calling it the “Outdoor 8 Rule,” Eckman wrote that one lesson beginning film photographers need to understand is that, to get a usable image, it’s not necessary to make a perfect exposure.
Indeed, as some of his readers pointed out, toy film cameras operate at roughly these settings when used with ASA 100 film. The Kodak Ektar H35 camera I had been contemplating and eventually came to own was one instance of this. The more I used my inexpensive half-frame camera, the more Eckman’s point was driven home: if I shot with a forgiving film like Fujifilm Fujicolor 200 at the camera’s set exposure settings of 1/100 sec. at f/9.5, or the rough equivalent of 1/125 sec. at f/8, I could expect at least passably decent exposures across a wide range of lighting scenarios.
Exposure Value (EV)
As I continued to poke around, I discovered the concept of exposure value (EV) and what it means.
Wikipedia’s article on the topic helped enormously. In the 1950s, German shutter manufacturer Friedrich Deckel developed a way to simplify choosing shutter speed and aperture down to one number. For instance, since shooting at 1/125 sec. at f/4 was the equivalent of exposing at 1/250 sec. at f/2.8, both were assigned the EV value of 11. Some manufacturers incorporated EV values into the cameras they made (check out the Kodak Retinette type 022, for instance).
The following is a simplified table that a photographer may have carried around for reference. It correlates aperture (column headers), EV (row headers), and exposure time for film rated at ASA 100 (source: Wikipedia):
Additionally, EV values were associated with various lighting scenarios. EV 16 was for harshly lit subjects on beaches and snowscapes, EV 15 for the typical scene in full sunlight, EV 14 for hazy sunlight, EV 13 for light cloud overcast, EV 12 for heavy overcast, and so forth.
Although manufacturer’s efforts to incorporate EV values into camera controls did not last long, the system does have value in the way that it distills exposure theory to something more manageable than a confusing jumble of shutter speed and aperture settings.
The database developer in me loves to see data like this. But memorizing an EV table seemed too hard and impractical. Having a single somewhat arbitrary number and translating it into shutter speed and aperture settings wasn’t really workable without carrying around a cheat sheet with a table of values. I wanted a system that I could commit to memory and that was a more natural match to the actual exposure speed and aperture settings on my Nikon F film camera.
At the same time, the Sunny 16 Rule seemed like a more useful basis for learning to shooting without a light meter, but it was too blunt of a tool. What else could I come up with?
Sunny 16 Equivalent Values
As I pondered the question, I realized that my existing body of photography could serve as one source of insight. But I needed to consider its metadata in a more comparable way.
With this in mind, I turned to my past digital photography where I had complete ISO, shutter speed, and aperture metadata. I came up with logic for my own “Sunny 16 F-number equivalent” value, which I derived from those three exposure settings.
In essence, I determined what an image’s aperture would reciprocally shift to if its shutter speed were changed to the fractional inverse of the image’s ISO speed (1/ISO).
For instance, consider a hypothetical photo shot at ISO 100, 1/250 sec., and f/8. If the shutter speed were changed to 1/125—i.e., the full-stop shutter speed setting that’s closest to 1/100, or the fractional inverse of ISO 100—the equivalent aperture for that photo to conform to the Sunny 16 Rule would be f/11. Doing that same kind of conversion on all my past photos and deriving a “Sunny 16 equivalent” value made all my photos more comparable.
The whole idea behind this was to boil the number of variables in play down to one. When making a decision about exposure settings, I realized it would be far easier for me to think in terms of just one variable, which of course is what the Sunny 16 Rule does in a very general sense. If I knew I had ASA 100 film loaded into my camera and that my baseline exposure time was 1/125 sec., for instance, the only variable that was left to consider was aperture. If I wanted more or less depth of field, I could set my aperture as appropriate and change the shutter speed reciprocally.
(I should digress here for a bit and make a note about ASA and ISO. Since film is rated using ASA while digital photography tends to use ISO, and since both are more or less interchangeable, I tend to refer to film speed in ASA terms and digital camera sensitivity in ISO terms.)
I had long since created a custom database application for managing my photography—again, this is the database developer in me coming out. Using this data, I wrote some programming to calculate a “Sunny 16 equivalent” value using the ISO speed, exposure time, and aperture metadata that my database application extracts from my digital image files. Writing the logic that derives that “Sunny 16 equivalent” value wasn’t easy, but I enjoy tackling those kinds of programming puzzles.
Meanwhile, I didn’t forget my encounter with EV. Around the same time that I was working on my “Sunny 16 equivalent” logic, I discovered that one can very simply calculate EV by plugging ISO, shutter speed, and aperture into the following formula:
EV = log2(100 * [aperture]2 / ([ISO] * [shutter speed]))
I love simple yet elegant solutions like this, and I couldn’t resist adding logic into my database application for making this calculation for each image.
I also remembered that my ultimate goal was not to get lost in computer programming puzzles but rather to learn how to shoot my manual film camera without the help of a light meter. Since my film camera only has settings in full-stop increments, my general approach was to round whatever third-stop ISO, shutter speed, and aperture values were recorded with an image to their nearest full-stop value. If I shot an image at a shutter speed of 1/160 sec., for instance, my programming logic considered that image as being shot at 1/125 sec. The same rounding logic applied to ISO and aperture. Again, I did all of this in the spirit of creating a simple usable solution.
If that derived “Sunny 16 equivalent” value falls outside of the practical range of apertures found on my film camera lenses (f/1.4 to f/22), I made use of my EV calculation to derive an additional value indicating whatever further adjustments to shutter speed would be necessary. If f/1.4 is at one extreme of my derived “Sunny 16 equivalent” metric, I would indicate f/1.4 plus however many full stops I would need to slow my shutter speed down to in order to get to the equivalent exposure settings for a particular image in a low-light setting. If f/22 is at the other extreme, I’d indicate f/22 plus however many full stops I would need to speed up my shutter speed to in order to get to the equivalent settings in a harshly bright setting.
The usefulness of my derived “Sunny 16 equivalent” value lies in the fact that it gives me an analytical framework that speaks to me in terms of real camera settings. It tells me how I would need to manipulate them when I actually have a non-metered film camera in my hands. And it does so more concisely and intuitively than what EV tables and their necessary conversions offer.
Getting Out and Practicing
Analyzing data and programming a computer to do conversions is one thing. Training one’s eye to judge real-world situations is quite another.
In addition to my programming work, I actually got out with my Canon EOS M50 digital mirrorless camera and practiced assessing a scene not for artistic composition but instead for making judgments about light pure and simple. That in itself was an education. It was the first time I had ever done anything like that.
As I got out there and practiced, I shot with my camera set to aperture priority and kept my ISO set to a single value throughout my session. If I had my camera set at ISO 100, for instance, I looked at a scene and tried to determine what aperture setting would get my camera’s light meter to choose a shutter speed of around 1/125 sec.
For a particular subject, I might have a mental conversation with myself that would go something like this: “Is this an f/11 situation? No, it’s too dim. How about f/8? Hmm... maybe it’s even an f/5.6 situation.” I made my best guess for an appropriate aperture setting, brought my camera up to my eye, set my aperture, and metered the scene. If I was right and my camera picked a shutter speed of around 1/125 sec., I patted myself on the back and took the shot. If I was wrong, I adjusted my aperture up or down to bring my shutter speed to 1/125 sec. All the while, I’d be making mental notes about what scenario called for what aperture setting for a given shutter speed.
Similar to how my “Sunny 16 equivalent” programming logic rounds whatever third-stop settings were recorded with an image, I evaluated my camera’s light meter recommendation by rounding it to the nearest full-stop value. Again, my ultimate aim was to be able to shoot my manual film camera without a light meter. Since my film camera has settings only in full-stop increments, I began training myself to think in terms of full-stop shutter speed and aperture increments. The same goes for ISO: I always choose an ISO setting that matches the ASA rating found on most film stocks.
Keeping a record of all three exposure settings—ISO, shutter speed, and aperture—became critical if I really wanted to learn from these exercises and begin to see a pattern. My modern kit zoom lens didn’t present a problem because my camera body communicates directly with the lens via its electrical contacts. Upon generating an image file, it has always recorded aperture along with ISO and shutter speed metadata.
When I got out in the past and shot with my old adapted lenses or my modern manual lenses, my camera still recorded shutter speed and ISO with my image files since both settings are made by the camera body. But it was incapable of recording aperture metadata since there are no means of communication between those old lenses and the camera.
Before I set out to teach myself how to shoot without a light meter, I never really bothered to note them. But now that I was much more interested in developing a keener sense of proper exposure settings for a given scene without the aid of a light meter, I began keeping better records. When using my older manual lenses, I often go old school and use paper and pen. (I must look odd to passersby who see me jot down notes every time I shoot an image.) When I’m back home, I transcribe that metadata into my photography database.
Since I’m interested in gauging light and not color in a scene, I also found shooting in black and white to be the most helpful. In black and white, I’m better able to assess light without the distraction of color. My Canon EOS M50 mirrorless camera’s exposure preview features was helpful in this respect. When my camera is set to monochrome mode, my viewfinder renders a scene in black and white, making it easier for me to do the kind of light assessment by eye that I’m seeking to get better at.
When I got out and actually started to think about my shutter speed and aperture settings more critically, I was often surprised to see what my camera’s light meter recommended to me for certain subjects. Seeing some landscapes under bright and direct sunlight on clear days, for instance, I would remember the Sunny 16 Rule and would often think to myself, “Oh, that’s definitely an f/16 situation.” But when I actually metered the scene with my camera with my ISO set to 100, I often saw that f/11 was the appropriate aperture setting if I wanted my camera’s light meter to pick a shutter speed of around 1/125 sec. That surprised me. “Wait a minute,” I thought to myself, “it’s clear and sunny afternoon, and I’m shooting a wide-open landscape at ISO with a target shutter speed of 1/125 sec. Why did my light meter go for f/11 and not f/16 like the Sunny 16 Rule calls for?”
It didn’t take me long to realize how much the Sunny 16 Rule is really only a very general starting point. I discovered how widely shutter and aperture settings can vary even when shooting various subjects in wide-open landscapes on clear and sunny days. In those settings, the Sunny 16 Rule says keep your aperture at f/16 and your shutter speed at the inverse of ISO (1/ISO). But in the real world, there was far more variation.
My experience reinforced what I read in Ben Long’s book Complete Digital Photography about how a modern digital camera’s light meter works. In his words, it does only one thing: “it measures the luminance [or brightness] of the light reflected by your subject.” As I soon learned from my own experience, various subjects reflect vastly different amounts of light. Accordingly, a general “Sunny 16” rule, albeit useful as a starting point, is incomplete. It doesn’t take into account the tones of a subject and the extent to which those lighter or darker tones affect the amount of light that is reflected off them.
Going back to my example shooting landscapes under clear and sunny midday skies, I found my digital camera’s light meter telling me that, if I wanted to keep my ISO at 100 and my shutter speed around 1/125 sec., I needed to shoot at anywhere from f/8 to f/16 depending on what tones were in my scene and how much sunlight they were reflecting. Had I blindly stuck with the Sunny 16 Rule and shot several scenes containing a lot of darker tones at ISO 100, 1/125 sec., and f/16, I would have underexposed many of my images by a stop or two.
Using my digital camera to develop my ability to shoot without a light meter is great, but there’s nothing like the real thing. As opposed to using a digital camera as a surrogate, I also prioritized getting out more with my Nikon F. One thing that really struck me when I began to scan negatives with a dedicated film scanner was how much exposure latitude I have with film. To be sure, there is no substitute for getting an exposure right to begin with. But even if my exposure was one or two stops off, I found still had a usable negative to work with. Sometimes an exposure even three stops off was still usable. Film photography proved to be much more forgiving than I expected when I was completely new to it.
More Data Entry and Analysis
Back home after a photo shoot session, I continued my analysis by doing some data entry. For each photo, I noted whether the subject was shot outdoors or indoors, the time of day, and sky conditions, all easy to do.
A fourth data point, describing subject lighting, was somewhat harder and took a bit more mental energy. But it was the most critical thing to do. For each image, I tried to characterize the subject lighting as best I could with an economical choice of words. By doing so, I essentially tagged an image with the same kind of mental assessment I made to myself out in the field.
In addition to analyzing the images I captured while I was out and about doing my light assessing exercises, I also went back to my older photographs that have complete exposure metadata (ISO, exposure speed, and aperture), and I did the same kind of analysis and data entry. Those files have time of day recorded with them, and it was obvious just looking at them whether my subject was outside or inside when I took the shot. Particularly for outdoor subjects, it was also obvious what kind of sky conditions I was shooting under. And just like I did with those photos I produced through my eye-training exercises, I made an assessment of subject lighting.
Before long, my efforts—my programming, my real-world practice, and my data entry—all started coming together into something I could really use in a very practical sense.
With a bit of effort, I now had a good body of useful and comparable data to learn from. With all of this entered into a database, I could now aggregate to my heart’s content (again, database developer here). For outdoor subjects taken under bright daylight under clear skies, for instance, what were the most common lighting scenarios that fell under a specific “Sunny 16 equivalent” value? What was the average “Sunny 16 equivalent” value for those photos whose subject lighting I tagged as being “direct sunlight on landscape with less sky in composition,” for instance?
At the time of writing (February 2023), here is my summary list for clear and sunny daytime conditions outdoors. With shutter speed set closest to the fractional inverse of ASA or ISO, I know to choose the following aperture for these scenarios:
- Direct sunlight on landscape with more sky (0.4).
- Direct sunlight on mostly lighter tones (-0.1).
- Direct sunlight on landscape with less sky (-0.4).
- Direct sunlight on mostly mid tones (0.2).
- Direct sunlight with some areas of shadows (0.4).
- Even blend of sunlit areas and shadows (-0.3).
- Direct sunlight on mostly darker tones (-0.3).
- Shady area with some sunlit areas (0).
- Shady area with open sky overhead (0.3).
- Deep shade with dappled sunlight (0.5).
- Deep shade (0.3).
Since I’m aggregating data, I can also tell how much variation there is for any given shooting scenario. The number in parentheses indicates the number of stops that a scenario may call for a slower setting (negative number) or faster setting (positive number). If there is a subject lighting scenario that varies by a half-stop, I might consider bracketing that shot. Or maybe my data entry was flawed and needs to be revised or refined.
This is the kind of list I can commit to memory. This is the kind of gut intuition I can develop and use to become a photographer who doesn’t rely upon a light meter.
Further confirming the validity of my work, I also found a neat correlation between my “Sunny 16 equivalent” value and EV. This table shows counts of my recent photographs and how their “Sunny 16 equivalent” value correlates with their EV:
The outliers on either side are probably the product of the kind of rounding I do to get to a full-stop value when calculating my “Sunny 16 equivalent” value.
Since my database includes camera and lens metadata, I can aggregate down to this level and see how much different camera/lens combos can vary. But I find an overall aggregation across all cameras and lenses to be most useful. After all, I want to keep this practical, something I can actually commit to memory and use in the field.
Is All of This Really Worth It?
So why does this all matter? Is learning how to shoot without a light meter an idle exercise in going old school just for the sake of going old school? Haven’t we progressed beyond primitive camera gear? Read any review of modern digital cameras and you’ll see that they spend a great deal of time on a camera’s automatic features (auto focus, metering, etc.). Are any of these old-school skills really relevant anymore?
Thanks to this whole exercise, I’ve gained a much better understanding of exposure theory than I would have achieved if I had simply gone on my merry way trusting the light meter, blindly following what it tells me to do, and simply letting the camera operate in automatic modes (program, shutter priority, aperture priority). And I’ve gained an appreciation for why understanding exposure theory is fundamentally important.
The benefits go far beyond developing my skills with using old fully-manual film cameras without a light meter. Even with a modern digital camera, I feel like I’m in a much better position to take the exposure recommendation from my camera’s light meter as just that: a recommendation. I feel like I can make a much better judgment about how to shoot my scene and achieve my desired artistic effect.
A camera’s light meter may take in a scene and recommend X or Y settings. With no knowledge or intervention on the part of the photographer, one is left to trust the camera purely on faith and do nothing except press the shutter button.
That’s boring! I don’t want to be that kind of photographer. Armed with better knowledge of what my light meter is doing and more experience with using my eye to make my own judgments about a scene’s light, I feel far less reliant on my light meter. I feel better equipped to use whatever camera I have in hand more effectively as a tool to achieve the end I have in mind when I see something interesting to photograph. Hoping that a light meter will get me to what I intended to accomplish doesn’t always work.
I’m reminded not only of what Henri Cartier-Bresson said about using light meters but also of what I thought to myself when I first read what he had to say. In a 1971 interview with Sheila Turner-Seed, he offered his thoughts on using light meters, which had become increasingly commonplace since they first began appearing built into cameras around the late 1950s and early 1960s:
I don’t see why it is done. It is a laziness. During the day, I don’t need a light meter. It is only when light changes very quickly at dusk or when I’m in another country, in the desert or in the snow. But I guess first, and then I check. It is good training.
“It is a laziness”? Humph! What a snob, I remember thinking to myself. But now I understand what he was getting at much, much better.
I’ll admit it: sometimes when I’m out and about with a manual lens on my mirrorless digital camera, I’m in a more easygoing mood and simply want to shoot. In these situations, I’ll set my camera to aperture priority. I may put some thought into what kind of depth of field I want to capture, and I’ll make aperture adjustments accordingly. Mostly, though, I find myself relying upon my light meter to do its thing and shoot away.
But my laziness in those kinds of situations—and, yes, Henri Cartier-Bresson was right: it is a laziness—doesn’t always get me to the best outcome. Even when I shoot in fully manual mode, I may still consider the recommendations of my light meter, and I may even be quite reliant on it in certain tricky situations. But in the end, I’m the one making the final decision when I press the shutter button. In automated modes, the photographer cedes that control to a computerized machine. In manual mode, there is far more consideration involved. That more deliberate act often results in a better exposure and perhaps even a better expression of artistry.
Sometimes it’s just fine to use automated modes. After all, modern light metering technology has become incredibly sophisticated and impressively accurate. But other times call for a more nuanced approach. Making a judgment about what approach is most appropriate for a given scenario is one key mark of a good photographer.
In the end, learning how to shoot without a light meter isn’t just a neat parlor trick to use with old gear. It’s given me a much better understanding of my craft, and it’s made me into a better photographer.