Manual Exposure and the Ansel Adams Zone System

Hi friends!

In this post I’m going to write about a few advanced photography topics: manual exposure and how to use the zone system that was discovered by the great photographer Ansel Adams.

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Manual exposure

Why would you go fully manual? And when is it most suitable to do this?

Let’s start with the “why“. Well, first of all manual exposure is the safest method for achieving consistent results. The camera light meters have evolved much in the last decades. They are getting better and better. For example my D500 has an excellent one. However no matter how good a meter is, it can still get “fooled” by harsh high-contrast lighting conditions. Manual exposure can help prevent this. But of course it requires some technique. You don’t just put the camera in fully manual mode, set some parameters and hope you’ll get tons of perfect shots. Unfortunately it doesn’t quite work like this. I’ll get into more details in the next sections.

Second, using manual exposure will help one understand light better. Light is after all the main and essential “ingredient” of photos so the better you understand it the better they will get! Let me re-phrase it: if you always set your camera on (full) auto it will be more difficult to observe the light because you know (or believe) the gear will get it done for you. So why bother understanding “light”?

Ok, now that I explained the “why” let’s continue with “when“. So when do I use manual exposure? The answer is: when time is not an issue and mostly for static pictures like landscapes. For moving subjects I usually use manual mode with auto-ISO due to the fact that light might change as the subject moves, say from sunlight to shadow or vice-versa. I simply don’t have time to adjust the settings in such situations so I prefer a semi-automatic mode. But the landscape doesn’t move so I can take my time. An exception might be when I’m travelling and I’m moving fast from one place to another. It is then when I switch to aperture priority and that’s it! But when I have the time and the subjects allow it I never hesitate to use the “fully-M” mode.

How do I use it? I’ll explain right away but first let me give you a piece of advice: always be aware that the light might change. This could happen for example when you alter the shooting direction/angle towards the sun or when our star suddenly “decides” to hide behind clouds. Be prepared to notice when this happens and adjust your setup accordingly. And yes, be proactive and check your settings from time to time even when you think the lighting conditions haven’t changed. After all, the light from the current moment is definitely different from the one you had one hour ago. Better safe than sorry…

Now let me explain how I use the fully manual mode.

First of all the exposure metering mode should be chosen. I usually use matrix for semi-automatic modes. However for manual exposure setup I often use spot as this is a requirement for applying the zone system. Sometimes I use central-evaluative metering, especially when I do natural framing from within a tunnel. Second, I set the exposure triangle (aperture, ISO, shutter speed). Finally I switch back to matrix as this is the default metering mode. Why do I need to revert to matrix? Because as mentioned in one of my previous posts, exposure metering is a globally setup parameter for D500 and therefore affects all shooting banks. If I need to switch to the bank used for moving subjects I want to have the metering already setup to matrix. For other cameras it might be different but anyway it’s advisable to restore a global setting to default once the change is no more needed.

Now let’s get back to the actual “exposure triangle” parameters that need to be setup. There is a “leading parameter” for each exposure. For static subjects this is usually the aperture, for moving subjects it is the shutter speed. This is the first one I set, even before I choose the metering mode. Then I set the ISO, usually to a minimum value. Finally I set the value of the remaining parameter (say the shutter speed) until the meter indicates the correct exposure and then switch the metering back to default. After the setup is done, if (at least) one of the parameters doesn’t have a satisfactory value I play with the exposure triangle until I get it right. However I try not to touch the leading parameter at all! For example if the shutter speed is too low (say 1/25 at ISO100, leading parameter aperture f11) and I need to increase it then I adjust the ISO accordingly. Always remember the rule: you add one stop to one parameter then you have to subtract one stop from another one so the exposure stays the same. So for obtaining a shutter speed of 1/100 out of 1/25 (subtract 2 stops of light) I would add 2 stops to ISO (increase it from 100 to 400). To sum up, you would like to get the right exposure and then fine tune it until it becomes the creatively right one. Actually you can setup an exposure triangle without even bothering too much about any parameter as long as the light meter shows it is correct. But then you need to adjust each parameter to get a creatively correct exposure by following the mathematics of adding and subtracting stops. Well, I prefer to have the leading parameter setup from the very beginning, it makes my life way easier!

But how does each metering mode work for manual exposure? Well from my experience I would say it works like this:

  • for matrix and centre weighted metering I usually want the meter to show me the centre of the scale in the viewfinder (null point, exposure value 0 EV). This is equivalent to the camera saying: “you achieved a correct exposure”. There are of course some exceptions. For example when I measure a green (grass) area on a cloudy day I would like the meter to indicate a -0.7EV underexposure. This is actually a method I learned from the book “Understanding Exposure” written by Bryan Peterson and it works pretty fine as far as I noticed. However most times the middle of the scale (0EV) is preferable.
  • for spot metering the situation is different. This is where the Ansel Adams zone system comes into play. I will talk about this in the upcoming section.

The Zone System

This originates from black & white film photography but is still applicable to digital nowadays. Many years ago, Ansel Adams mapped the picture tones into so called exposure zones. In film photography he identified 11 zones ranging from absolute black to paper white. However in the modern digital photography only five of them are still being used. These are the zones 3, 4, 5, 6 and 7 which correspond to the segments of a histogram as follows:

  • zone 3: blacks (or darks). This is the darkest area of a photograph and covers the extreme left part of a histogram. If the histogram touches the left margin of the scale then no more details are visible in that part of the picture, it is too dark for them to be perceived. The details can be recovered nonetheless, often at the cost of increased noise.
  • zone 4: shadows. This is still a dark area but more details are visible. It is the next left section and precedes the mid-tones.
  • zone 5: mid-tones is the middle area of the tone distribution. If the contrast is low then this might actually be the only area visible in the histogram.
  • zone 6: highlights. This is the fourth section of the histogram (next after the mid-tones) and shows the colourful bright parts.
  • zone 7: whites (or lights). This is the extreme right part of the histogram. Everything that is white or light grey stands there. If it touches the right margin then no details are visible anymore, that part of the photo can be described as too bright or “burnt”. In contrast to darks the lost details from this zone are often hard if not impossible to recover depending on how much of the frame is being overexposed and how high the dynamic range of the sensor is.

The principle that stands for the zone system technique is: map the objects from a frame to the right zone from the histogram. In other words what you see as a shadow should be placed in the shadow part of a histogram, same for highlight etc. For example if you see a bright but colourful object (like a green painted wall lit by the sun) where would you place it? Well, I would say its pixels should show up in zone 6. This can only be safely done by using the spot light meter.

Ok, easy to say but how do I apply this technique? The simplest way to achieve this is bother only with the last two zones (6 and 7). This is because as mentioned before, it is more difficult to recover details from burnt bright areas than from shadows/darks. Consequently I follow these steps:

  • first, I switch exposure to manual and set spot metering, the leading parameter and ISO
  • second, I check which the brightest part of the frame that still contains details is. This rules out light sources, like the sun or a lamp. I place the focus point (spot) in that section. When doing this I make sure the spot covers a uniform bright area. This is after all the point of using this metering method, otherwise I would probably use another one (and no zones). It really needs to be as uniform as possible!
  • thirdly, I decide in which zone the metered piece of frame should be placed. If it is zone 6 I will adjust exposure until the meter shows +1EV in the viewfinder scale. If it’s in zone 7 then I adjust until I see +2EV. This is how the actual mapping to zones works.
  • finally I switch back to matrix metering, fine-tune the exposure triangle as previously described and start shooting

Let me give you some examples of zone choice:

  • a bright white cloud with details would always be in zone 7
  • bright orange sky at sunset would be in zone 6
  • blue sky might be in zones 5 or 6 or even below depending on time of day. It takes some practice to determine this. During daytime I would put it into zone 6. After sunset I would place it into the mid-tone section.

Does it look simple so far? Well, it might look but it ain’t! Let me share with you some further findings (and caveats!):

1) This technique is not exact science as it’s accuracy depends much on how good the light meter of the camera is and also on your “eye-meter”, as the brightness of an object does not always make it easy to determine the right zone. Consequently I advise you to regularly check with the histogram on the display to see how it behaves . Also if you have “blinkies” on your LCD they are a valuable tool which can be used for identifying overexposed sections of the photo that lack details. So if the result of using zones is not satisfactory adjust the exposure as needed, either by increasing or decreasing its value until you get the desired tones distribution.

2) It might be confusing when more bright zones of different colors are available. For example which one would you choose between a light green tree and the blue sky? Both might be in zone 6 but you will most probably get different results. My advice to you: try one of them, check the histogram and if the result is not the desired one then re-apply the technique to the other. Or just adjust the exposure until you nail the right setup. As already mentioned it’s not quite an exact science, ain’t it?

3) Also it might not be 100% clear which the brightest piece to be measured is, even on the same “object” (say a cloud). To ensure you get the best possible exposure you might want to proceed like this: choose the part you think is the brightest and adjust your exposure by using the spot metering as described above. Don’t change the metering back to matrix yet but instead slowly move the focus point onto the surrounding area of the metered piece. Keep an eye on the viewfinder scale and observe if the overexposure increases and if yes, take a note about how much. For example if it increases from +1EV (the value shown by meter after the setup done by you) to 1.7EV then you might want to adjust the settings again to decrease overall exposure by -0.7EV. After you’ve done this, it’s time to revert your metering to matrix, fine-tune the triangle and start shooting.

4) By all means shoot RAW if your camera allows it! Even if your exposure is perfect there’s still room for improvement at editing. After all, it’s not only about exposure but also about shadows, highlights, contrast, color saturation and others. Of course even when shooting RAW one should strive to get the best possible setup as this means less editing work.

5) When checking the “blinkies” if you see a burnt “area” don’t panic. If the area is reasonably small (say maximum 1-2 percent of the picture) most probably the details can be recovered at editing (again: if shooting RAW) so no need to take another picture. However if a larger area blinks, then I would advise you correct the exposure and take a new picture. Better safe than sorry.

6) Pay attention to very bright colors. Sometimes you might think the color is white but when you look again you might find out it is light yellow or light orange. In this case you might want to  expose +1EV relative to light meter (or slightly above – see point 8) otherwise the color will get “burnt”.

7) Try to choose the piece to measure from a section you wish to include in the frame, otherwise the results might not meet your expectations. Light can dramatically change from one side to the other so try to avoid using a metering area that will not appear in your picture.

8) You are not bound to the +1 EV and +2 EV overcompensations. Check below pictures: part of them are slightly underexposed and part of them are slightly overexposed (the under-/overexposure small though, say +/- 0.3 EV). If you know your sensor can handle it, you might go ever further. For example if a cloud is extremely bright you can set exposure to 2.3 – 2.7 EV relative to meter, which might render the exposure even more accurate. In other words you could push as far as possible but not beyond the point you cannot recover details anymore. I would say 0.3 – 0.7 EV extra cannot do much harm, yet this depends much on the sensor dynamic range so take this statement with a little grain of salt please!

Bottom line: it takes a lot of practice to assimilate this technique. You need to take hundreds or even thousands of pictures in many lighting conditions to get used to it. And getting used does not mean mastering it! You have to get to know your sensor very well, to know what it can do and what it can’t. But I’m positively sure you’ll get to love it once it becomes part of your core knowledge of photography setup. Again, this is pretty advanced stuff and it requires some good understanding, patience and probing.

Below there is a small gallery of pictures most taken by using spot metering and the zone system. I haven’t edited any of them as I wanted you to see the “raw” result of using manual exposure and the mapping to zones. Each picture contains a comment about what exactly was measured and the overcompensation value indicated by light meter.

I hope this article will help you improve your photography technique. For more information about these topics I recommend you two books. First is “Understanding Exposure” which was written by Bryan Peterson. Second is “Digital Landscape Photography” by Michael Frye, which discusses the zone system in detail.

To conclude, I hope my post helps debunking common myths like “manual mode is only for professionals” or the other extreme, namely “I need to use manual mode, otherwise why in the name of God did I buy a DSLR”? My answer to you is: manual mode is for EVERYONE interested in getting consistent results and taking good pictures in general. The only thing that needs to be taken into account is to use it with good judgement, i.e. know HOW, WHY and WHEN to use it. It is not rocket science but more like common (photography) sense.

Take care and may you catch the best possible light!

P.S. Check this posts too:

The Bucharest International Airshow (BIAS) – 2019 Edition
The Magic of Fog. Welcome to the Misty Mountains!
D500. Further Impressions and My Findings about Setting It Up
Rivers and Waterfalls
Spiders. And Some Findings About Photographing Them

  1. Spot metering, focus point placed on the brightest part of the clouds and the exposure set to +2 EV as shown by the viewfinder scale.

2. Spot placed on the building, +1 EV

3. Spot placed on the lower part of the sky, +1 EV

4. Spot placed on the large cloud, + 2 EV

5. Spot placed on the rock, middle part of the frame, +1 EV

6. Spot placed on the sky, +1 EV

7. Spot placed on the sky, +1 EV

8. Same picture, two different exposures: first with spot on the tree leaves (+1 EV), second with spot on the sky (+1 EV). Unless you do HDR you might want to prefer the darker one as it’s easier to recover details from shadows than from lost highlights. Actually this is one of the goals of the zone system, namely to prevent getting blown highlights. You might also try to push the exposure as much until the first “burnt” areas appear and keep it this way as long as these are only a tiny portion of the frame. To say it otherwise using the zone system is somewhat like exposing for the bright parts and dragging the darker areas behind them.

9. Spot on the red leaf, +1 EV

10. Spot on the sky, +1 EV

11. Spot on the leaves, +1 EV. Although the sky looks overexposed this is not much of an issue as it covers only a small part of the screen and the leaves are the main subject anyway.

12. Spot on the sky, +1 EV

13. Spot on the sky, +2 EV. The light was too harsh to take a quality picture, yet I thought this frame might be useful for “educational” purposes. As can be seen there are no blown highlights in the picture.

14. Spot on the yellow leaves, +1 EV

15. Spot on the sky, +1 EV

16. Spot on the sky, +2 EV

17. Spot on the sky, +1 EV

18. Spot on the sky, + 1 EV

19. Spot on the sky, + 1 EV

20. Spot on the sky, +1 EV

21. Spot on the sky, +1 EV

22. Spot on the sky, +1 EV

23. Spot on the building, +2 EV

24. Spot on the sky (left corner), +1 EV

25. Spot on the sky, +1 EV

26. Spot on the sky, +1 EV

27. Spot on the lotus leaves, +1 EV. Although some blown highlights exist these can be partly ignored as the main focus is on the translucent leaves which are beautifully backlit.

28. Spot on the sky, +1 EV

29. Spot on the left side of the building, +2 EV

30. Spot on the sky, +1 EV

31. Center weighted metering placed on the bright side of the soil, 0 EV

32. Spot placed on the top bright part of the leaves, +1 EV

33. Spot on the sky, +1 EV. However I also placed it on the lower part of the lamp (bright part) and I got the same results from meter to which I added the stop of overcompensation.

34. Spot on the white part of the barrier, +1 EV (it’s slightly yellow so I chose not to put the +2 EV used for white/light grey areas)

35. Spot on the upper part of the building, +1 EV (not quite white either)

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