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Photography Workshops by Canon Northern Explorer of Light Christopher Dodds


Christopher Dodds Nature Photographer | Promote Your Page Too

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Basic Exposure Theory: The Sunny F/16 Rule Explained

Snowy Owl Bubo scandiacus (Harfang des neiges) Casselman, Ontario. Image Copyright ©Christopher Dodds All Rights Reserved. Canon EOS 1DsMKII, 500mm F4 IS ISO 400, F5.6 1/1600s Manual mode. Full Frame. The chart below (in the cloudy bright column) shows the correct exposure to be ISO 400 F/11 @ 1/400s. I chose to stop the action by using a higher shutter speed, so I used the equivalent exposure of ISO 400 F/5.6 @ 1/1600 second. I also knew to expect less detail in the snow and white feathers, because there are no shadows to help define them.

What you shooting at there, Dodds?” echoed across the landscape as I set-up to photograph Snow Geese and Sandhill Cranes in New Mexico about a year ago. “What exposure you at Dodds?” was the question asked by the same gifted photographer just recently. I don’t want to embarrass anyone, so I won’t mention any names here. I truly do think that he is a gifted and talented photographer. He’s widely published and is also the first person to admit that he doesn't really know all the “techie” stuff.....and he was much closer to my exposure this year, than last. 

The single most important skill a photographer should have is a basic understanding of the fundamentals of photography. The most important tool, and the least understood aspect of photography is exposure theory. I learned photography with a totally manual camera and used slide film (seems like so long ago), so a basic understanding was necessary to make successful images.

 Q: Why bother when I can just keep things simple and take a picture, check the histogram and make any adjustments necessary? 

 A: Because having an intimate knowledge of exposure theory and your cameras functions and controls helps you grow and improve as a photographer, make better decisions and better images as a result.

In it’s simplest form, the Sunny 16 rule (or Sunny F/16 rule) states: On a bright, sunny day, the correct exposure for any middle tone subject is F/16 at the shutter speed nearest to the reciprocal of the film speed. For example:

ISO 100 = 1/100 second @ F/16

ISO 200 = 1/200 second @ F/16

ISO 400 = 1/400 second @ F/16

ISO 800 = 1/800 second @ F/16

Now we have established the correct exposure, it’s time to decide if we need more depth of field or shutter speed. Each step up, or down, of one variable represents a doubling, or halving, of any other variable. If you need more shutter speed than 1/100 second @ F/16 (ISO 100), then an equivalent exposure would be ISO 100 1/1600 second @ F/4.


This chart illustrates the equivalent exposures for ISO 100 and 200. Each setting above will allow the same amount of light to fall on your digital cameras sensor, or film cameras film. The exposure is the same, with the only difference being either your shutter speed (to freeze or blur action) or the depth of field (very narrow to blur the background, or very large to capture an entire grand landscape sharp).

But wait! It got cloudy. Now what? The Sunny F/16 rule is actually the correct ambient exposure for an average subject under bright sunny conditions. If the sun goes behind a cloud, then the light falling onto your subject is decreased and you must make an adjustment to your basic exposure settings. Here are some aperture settings for some different daylight situations:

This is intended as a starting point, so there are exceptions. Backlight or sidelight both require adjustments to reach the correct exposure. It’s a good idea to expose to the right with your digital camera; 50% of the recorded data is recorded on the right fifth (or 20%) of your digital cameras histogram. With very light subjects in very bright conditions, I routinely subtract light so as not to clip the highlights. With very dark or black subjects, I tend to add light to maximize the recorded detail. Notice the technicals for the Snowy Owl in my previous post; ISO 200 F9 1/1600 second = ISO 200 F22 1/1250 second (or Sunny F/16 rule for light sand or snow) minus 1/3 stop to preserve all of the details in the whites without clipping (or loosing) any data.

Sounds complicated, but if you spend some time digesting and thinking about everything here; you'll be able to get that once in a lifetime shot accurately and consistently with confidence. Not to mention how much you will impress the boys (or girls) when you are all standing around waiting for the shot or talking shop.

If you own an iPhone or iPod touch, there's a great application available for $1.99 called Exposure Calc. I just found it while writing this blog entry and think it is a great learning aid and pocket reference.

If you don't get it, and need to take a test shot, check the histogram, make adjustments, take another test shot; that's okay too, as long as you're having fun and making the odd good image to keep you interested.

Comments welcome & appreciated.

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Reader Comments (18)

Once again Chris you come up with a winner of a lesson for everyone. I am happy you found that app for the iPhone and Touch. I am going to post a link to your blog for all the members of the Montreal Camera Club to access to your wonderful site. Keep up the great work you do and thank you for sharing all this info with us.

January 12, 2010 | Unregistered CommenterJohn Zimmerman

Thanks so so much for this Chris! Truly great info! Hope to see you again soon - your work is truly inspiring!!

January 12, 2010 | Unregistered CommenterDiane Dupuis-Kallos

Great post! Thanks a lot Chris!

January 13, 2010 | Unregistered CommenterGerry

Thanks, folks!

Glad you found it helpful.

Very best,


January 13, 2010 | Registered CommenterChristopher Dodds

Chris' comments and recommendations are interesting and worth keeping in mind when exposing in different light/exposure conditions. I had a look at his blog and hope to benefit from it ! Snow alone is difficult to find the right exposure for and even trickier when you have a white subject you expose for so it should come out right! I, like some of us, I guess, relied on the exposure meter only at times - and found, of course, that there was more grey than the desired white after downloading the shot! The trouble is, of course, that you should almost carry the info with you--or have it in your head, or change your exposure before you even go out!- When you are lucky enough to see a snow owl, you get too excited and start shooting without thinking about all the recommendations! I have been lucky to come across an owl in the Morgan Arboretum, years ago - when I was x-country skiing with my camera slung around my neck. I got so excited about seeing it that I just grabbed my camera as fast as I could to get a shot - Even though I had taken the snow into account and thought I had compensated enough to avoid it from coming out grey, I did not expose adequately to get the pure white I wanted. You can, of course, fiddle around a bit with PHOTOSHOP - but it never really seems to do as good a job as exposing properly to start with! I guess the answer for me now is: try to remember the recommendations as much as possible and don't get too excited when I come across a snow owl!But , then I also have to remember to keep my balance on my x-country skis which - at close to 80 years of age (in March of this year) is another factor I need to take into account! The worst thing that happened to me, a few years ago, was going X-country skiing ALONE in fairly warm winter weather. I came across what I thought was a field, started to cross it, only to find out that it was a large pond! Since it was not too cold, its surface had not frozen solidly- and I sank into the water up to my waist! It then took me forever to get out-using my crossed ski poles to support myself sufficiently to avoid sinking in even more! Since I am writing to you, you realize of course, that I survived this ordeal. In fact, it took me an hour to get back to our rented cottage - and by that time I not only started to get slightly frost bitten but also to tremble due to a combination of freezing and fright/concern of not getting back alive!! And then, I did the most stupid thing: when I got back, i stuck my legs into WARM water -which was the absolute wrong thing to do. As a result, I started to get blisters and aweful pain in the area of my legs that had been in the freezing water!! - But, since I am writing this to you, you realize I am still alive and kicking! So, the answer for me now is, expose properly for owls in snow- and make sure to avoid exposing my privates orthe rest of my body in freezing water when lucky enough to come across a snow owl with my camera! Lots of stuff to remember, one of use for photography, the other one vital for one's survival. Both are important - but survival beats photography! Regards, Gerhard.

January 13, 2010 | Unregistered CommenterGerhard Hasse

Thanks for the refresher on the rule of "sunny 16". I know during the workshop you explain to us several times, but this is a great reminder.

January 13, 2010 | Unregistered CommenterMelody

Wow, Gerhard, that's quite a story and I'm glad you are still around to tell it. Please stay safe during your future expeditions and stay far away from lakes and ponds! Thanks for sharing it here.

January 14, 2010 | Registered CommenterChristopher Dodds

Excellent reading Chris. Thanks for sharing those technics. While processing my old files I found many images where I just wish I had the right knowledge on bird photography. But as you said practice makes it towards perfection. Fully agree.

I am keeping in mind all my mistakes I made earlier but all the mistakes could be beneficial when in the field again.

Cheers, Szimi

January 14, 2010 | Unregistered CommenterGyorgy Szimuly (Szimi)

Thanks for posting here, Gyorgy - good points.

January 14, 2010 | Registered CommenterChristopher Dodds


Stumbled onto your website this evening. Thanks for sharing your knowledge. The technical stuff can be explained and learned, but the either got it or you ain't...Christopher, you got it. Awesome, inspiring images.

Gray Hiker
(not as gray as Gerhard, but closing in)

May 30, 2010 | Unregistered CommenterGray Hiker


November 3, 2010 | Unregistered Commenteranupam bhattacharjee

Very detailed and helpful guides for long exposures technique. I just understand how photographers may create picture with colorful light for objects. Thanks so much

February 24, 2011 | Unregistered Commenterxpose

I have tried so hard to understand this and now I am finally beginning to get it thanks to you Chris.

FANTASTIC, thank you for taking the time to share your knowledge!


August 7, 2011 | Unregistered CommenterAndrea

I was out in the Eastern Sierra Nevada last week with my Canon XSi and was very frustrated because the meter was all over the map and I was getting inconsistent exposures. I remembered the sunny f16 rule from the recesses of my mind, went to manual and like magic my photos were perfectly exposed !!!! problem was the next day it was slightly overcast then cloudy and also was shooting in some snow (high elevation hiking) and I did not know how to compensate properly. A quick search on the "sunny f16 rule" found this blog. Great article explaining how to compensate for these other conditions and thanks for pointing me to this app.

August 15, 2011 | Unregistered CommenterChris

Great post, very helpful - thank you

August 20, 2012 | Unregistered CommenterRachel

Thanks for your kind words, everyone.

Very best,


August 20, 2012 | Registered CommenterChristopher Dodds

Hi Chris,

I'm from India andI have recently taken to bird photography (you can see some of my images on my Facebook page - and your blogs on exposure and bird imaging have been fascinating. I'm trying to get to understand photographing birds in flight better - I know you suggest a shutter speed of 1/3200 to freeze the action. I was wondering if you could help with a table for BIF photography exposure settings with 1/3200 shutter speed as the constant and giving corresponding ISO and aperture settings for overcast, cloudy, cloudy bright and sunny conditions as you have above.



October 31, 2013 | Unregistered CommenterSunder

This is a very comprehensive explanation. Cheers for sharing.

June 25, 2015 | Unregistered CommenterMelvin Mapa

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