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The Sunny 16 Rule

by David Peterson 32 comments

Have you ever heard of the sunny 16 rule? It seems to have all but disappeared in most modern discussions of photography. As a matter of fact, it’s one of many rules that photographers seem to have forgotten. That’s a shame because the sunny 16 rule serves as a nice way to check your current exposure settings. Let’s have a look at how it works.


Long before the time of digital cameras, photographers invented rules to help them navigate their camera’s manual settings. Photographers had to carry light meters with them everywhere they went, and they were virtually lost without them. But if you didn’t have time to take a light reading, or you didn’t want to bother with carrying the equipment, you could resort to these rules. They were the next best thing.

And it's still pretty handy to know what manual mode settings to use with your camera.

How does the sunny 16 rule work?

The sunny 16 rule works like this:

  • On a clear and sunny day, at an aperture of F/16, you will get a correct exposure if you use a shutter speed that’s the inverse of the ISO speed you’re using.
  • The second part is probably the one that’s confusing you (if any of it is). You have to know what ISO speed is in order to decipher what’s going on. So allow me to explain.

The easiest way to explain is with an example. If it's a sunny day, and have your aperture set to F/16 and ISO set to 200, to correctly expose your image the shutter speed needs to be set to 1/200 (the inverse of the ISO number).

ISO speed is your camera’s sensitivity to light. A bigger ISO speed means a larger sensitivity. If your camera is more sensitive to light, it takes less light to make a picture more bright. Most cameras start out at an ISO speed of 100, and some models go as high as ISO 1600. That’s 16 times more sensitive than the default, meaning you’d need to expose the camera to 16 times less light in order to get the same picture. I talk more about ISO in ISO Explained.

Keep this in mind because you’ll notice a pattern. The rule says you need to use the inverse of the ISO speed. That’s interesting because as you increase your ISO speed, you effectively have to increase your shutter speed to compensate. At ISO 200, your camera is twice as sensitive to light, so you need to use a shutter speed of 1/200 of a second to let in less light and balance it out.

Let’s use another example. Let’s say it’s a sunny day, and your camera is set to ISO 400. According to the sunny 16 rule, if you use an aperture of F/16 and a shutter speed of 1/400 s, you will have an evenly balanced image that is neither too bright nor too dark.

That’s interesting, but it seems like the rule can only help us out when it’s sunny.

Are there other rules for different shooting conditions?

You bet there are. They’re just not as easy to memorize.

How about:

  • The snowy/sandy F/22 rule.
  • The overcast F/8 rule.
  • The slightly overcast F/11 rule.
  • The heavy overcast F/5.6 rule.
  • The sunset F/4 rule.


Depending on the weather, you can use a different version of the sunny 16 rule to get an accurate exposure.
Photo By Jason Rogers

But wait. It gets ever better than this. You don’t always have to use F/16 on a sunny day or F/8 on an overcast day. These are merely starting places. As long as you compensate by adjusting your shutter speed along with your aperture, you can use any aperture you want under any lighting condition.

So, let’s go back to the drawing board and imagine another situation. What if it’s a bright sunny day, and there’s a landscape you want to photograph? You could use F/16, but you want to use an aperture that really gets the entire depth of field in front of you. You really want to use F/22. What can you do?

Start with a pair and move forward from there

Let’s also assume you’ve set your ISO to the minimum of 100. According to the sunny 16 rule, we’ve got a pair. You know that F/16 at shutter speed 1/100s will work. Now we simply need to find a similar pair by adjusting the aperture and balancing it out with the shutter speed.

Thankfully, apertures and shutter speeds work on a system of stops. Every time you adjust your shutter speed up by one stop, your camera lets in exactly half as much light. The same is true for apertures. Every time you adjust your aperture either up or down, your camera lets in or blocks out half as much light.

Well, that’s not entirely true. Some cameras allow you to adjust the aperture and shutter speeds by half or quarter stops. But let’s ignore that for now.

So all we really need to do is keep moving our aperture up one stop and our shutter speed down one stop until we get to F/22. Let’s give that a try.

On my Nikon D40x, the next aperture stop up is F18. The next shutter speed stop down is 1/80s.

It then goes to F/20, 1/60s

And finally, it arrives at F/22 shutter speed 1/50s. You’ll notice that the shutter speed is exactly half of what it was at F/16. That makes sense because we’ve just closed the aperture by one half, so we need twice as much light to take the same picture.

You’ll also notice that the D40x works on a system of quarter stops. It’s a little different from the standard in photography, but the same rules apply. Every time you adjust the aperture up, you need to adjust the shutter speed down. Every time you adjust the aperture down, you need to increase the shutter speed by one stop. Keep doing this until you get to the aperture or shutter speed you want to use.

Even with all this expensive gear, the sunny 16 rule can still come in handy. Sure, you can use your camera’s light meter, but it isn’t always the most accurate. I like to do the sunny 16 calculations in my head so I at least know what the ballpark shutter speed and aperture values will be. If I’m close to those numbers, I’m usually pretty happy.


The sunny 16 rule is just a starting point. Use it come up with any aperture and shutter speed combination. In this case, the photographer picked a smaller aperture to capture a larger depth of field.
Photo By Michael Kirwan

The sunny 16 rule isn’t an end all be all. I wouldn’t allow it to supplant good old trial and error. Keep checking your LCDs and histograms. It’s much more valuable than knowing the sunny 16 rule, the overcast F/8 rule, or whichever rule you need for a given day. There is no such thing as a “correct” exposure, after all. It really does come down to your own aesthetic sense. This is just a guide to help you get there.

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Comments

  1. steve says:

    hi
    my daughter is getting married on the beach in Cyprus in September this year I would like to get quite a few photographs of the happy couple , it will be on sand and knowing Cyprus will be very sunny what aperture do you think I should use and iso speed, also I would like to capture some of the photos in black and white any idea of the best lens , apertures and iso speeds ?

    • David Peterson says:

      Hi Steve,

      Congratulations on your daughter's wedding!

      Wedding photography is difficult at the best of times, and a sub-tropical cloudless sun is going to make it really hard to capture both the white of your daughter's dress and the blacks of the groom's suit. (That is of course if they are wearing traditional western attire).

      My advice would be to photograph them under some shade. Use a fast lens (like f/2, or f/4.5) to blur the background. Because of all the light getting into the camera, you'll need to use a low ISO (100, or 50) and a very fast shutter speed. Choose Aperture Priority (or Portrait Mode) and your camera will help you out with this.

      Good luck!

      David.

      • steve says:

        thankyou very much that really helps me alot will practice when we get lots of sunshine here in the uk ( lmao ) my daughter has a pro photographer already to do the photos , but hopefully I might capture moments he misses.

        cheers
        steve

  2. Monika Fox says:

    Thank you so much for this! I only purchased my very first slr few weeks ago. It was always my dream to learn taking photos and I'm far from professional and will be learning for the rest of my days but me and my D750 are a great team. And exactly articles like this one helps so so much on my journey. I understood almost everything ;)
    And might just become your biggest fan and lose myself in all published secrets here :)
    22C tomorrow - I'll try it out that sunny 16 rule :)

  3. Masayoshi John Otomo says:

    I tried your settings suggestions and fired it up. I was astonished on the result and now getting a better grasp of my old camera. Thank you so much. It helped me alot in understanding how to use my photo buddy. I'm not into photoshop so I want everything to be raw(fresh from the camera) and the fact that I'm more into landscape than events or portrait. Again thank you so much for that brief yet effective tutorial.

  4. Nika says:

    Thank you! so far that's the clearest explanation I have found. I do have a question though. If I was to shoot outdoor portrait in very sunny day and wanted to use f1.8 (as a want blured DoF) would this rule apply? With my Nikkor50mm and NikonD610 shutter speed gets to 1/4000s. What would be the best setting for perfect exposure?

    • David Peterson says:

      Hi Nika,

      No. The sunny-16 only works with f/16. When you change the aperture to f/1.8, you're letting more light into the camera, so the shutter will need to be faster than the focal length.

      I can't give you exact numbers because I don't know your exact lighting situation (why? look here: http://www.digital-photo-secrets.com/tip/2140/why-dont-you-tell-us-which-settings-to-use/ ) but the easiest way to know what settings to use to perfectly expose an image is to use the Auto mode of your camera to take a test shot with that lighting condition (and f/1.8). Then look at the EXIF data for the shot and that will tell you the settings for ISO and Shutter the camera used. You can then switch back to manual mode; dial in those settings; and you'll be fine!

      More explanation: http://www.digital-photo-secrets.com/tip/4079/exif-improve-your-shot/

      David.

  5. Ray says:

    Hi David,

    I was a beginner at night photography and read an EXIf and went out to capture a cityscape at dusk. The cityscape image came out super excellent at f11, iso 100 and shutter speed10 seconds, AWB, Mirror locked, Tripod used, Evaluative metering, timer 2 sec (Manual mode used). Since that day for some odd reason, I have been trying to capture all dusk pics with f11 but many a times it has not worked. I want to keep iso at 100 or 150 max and shutter speed 10-15 sec. Should I try lower f like f 7/8/9 ?

    Also, what setting should I choose for AF points (My camera has 19 pts) for night photography mainly cityscapes and docks ? All 19 or center point ? I want crisp images and good reflections.

    Thanks in advance !!

    • David Peterson says:

      Hi Ray,

      It's all going to be based on what light is around, and that can change from minute to minute at Dusk.

      What do you mean by 'not worked'? If your images are too dark, then increase the shutter speed and try again. If they are too bright, decrease the shutter speed before trying again.

      I'd leave your aperture at f/11 unless you find your shutter speed needs to be too long and is introducing too much noise. In that case, change to f/8 and decrease the shutter (to counter the extra light you're letting into the camera with the aperture change).

      At f/11 almost all of your image will be in focus, so you don't need to worry about your AF points. Anywhere in the scene is fine. If you want a spot to focus on, focus on the further-most near object in the scene.

      I hope that helps.

      David.

  6. Carmen says:

    Hi there,

    Your article is the simplest explanation I have come across yet. I'm currently a photography student and my biggest issue is getting what I see to come out in the camera. Exposure is my biggest obstacle in that several of my pictures sometimes have a flat feel. For example, I want to take a shot of a bike that is currently in a tree...its a sunny day, I want to use ISO 100, I want to be able to capture just the tree and bike in focus in the foreground, and have the background blurred a bit. The lowest F-stop on the the lens I'm using is 5.6. How can I make this magic happen? Help!

    • David Peterson says:

      Hi Carmen,

      Regarding blurry backgrounds, it sounds like you're doing almost everything right by using a low F-number. What's probably happening is you don't have enough distance between the tree/bike in the foreground and the background you want blurry. You can usually fix this by getting closer to your subject (but don't zoom out as well).

      See this article for details: http://www.digital-photo-secrets.com/tip/5252/ask-david-arent-backgrounds-blurry/

      David.

  7. john w says:

    Hi thanks for all the information, I have a question , if im using ISO 400 and want to take a portrait shot , I cant do that and get a blurred background, as I will have to use a F16 , and wont be able to get the F stop down to 2.8 of 4
    is there any way of bringing the F Sop down and keeping every thing exposed correctly, other thand changing my film to ISO 100
    hope you can help
    many thanks

  8. Patricia says:

    Thank you! I am just starting out and this advice is the most comprehensive so far. I will try this out the next time I play with my camera.

  9. Ray says:

    Sir,

    Does this rule apply to birds in flight too ?
    What if I am trying to capture a flying heron on a sunny day and I need 1/1000 ? Or a very restless chickadee on a branch ?

    I am an ametuer.

    Thanks !

  10. Don says:

    David

    Some people might be interested in where the ISO comes from.

    How did film manufacturers determine a film's speed? Remember there were no light meters back then.

    The American Standards Association, ASA, developed a procedure for determining a film's speed. Take a picture on a clear day at noon in July on the Washington D.C. mall. Actually take a bunch of pictures at f/16 and various shutter speeds. Develop the film and find the best exposed negative. The film speed is the reciprocal of the shutter speed used.

    There were several other film speed ratings. Weston (the light meter people) and the German DIN (Deutsche Industrie-Norm) were the most common. Kodak film boxes were marked with ASA & DIN speeds.

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