A beginner's guide to getting correct exposure...

Steve Reddin

There's no getting away from it, the basics of photography are confusing. All you really want to do is take nice photos but you're not sure where to start. You ask a photographer for information and receive a tide of focal length, aperture, ratios, now you need to change aperture because you've only gone and changed lens...

...so, for those just introducing yourselves to photography and just itching to choose M on that wheel dial thing on your camera (but scared the gardai will call around for a quiet chat when you get it wrong) I've written this guide to delving into exposure. I've tried to write it such that the complexity increases only as you go along, but you can jump off board after Part 2 with enough to get going or read the entire thing for complete exposure control, or anywhere in between to suit your individual curiosity.

FYI, for the experienced photographers, I know I may have, for ease of explanation, knowingly use terminology or say something in a manner that is technically incorrect. Now, if I'm just plain wrong, that's a different matter...

Part 1 - A starting point with the Sunny 16 Rule

With all the settings available one difficulty is just knowing where to begin. Thankfully, the Sunny 16 rule (S16 hereafter) gives us this starting point. If you want to know why keep reading, if you just want to use it and get nice photos skip on down to Part 2...

The S16 rule is a point in the trilogy of shutter speed, ISO and aperture (search boards.ie for explanations on each of these) that, for specific conditions, will give you a correct exposure. These conditions are:

• the subject is in clear sunshine
• your aperture is f 16
• your ISO is paired to your shutter speed, e.g.

ISO 100 / shutter speed 1/125s, ISO 200 / shutter speed 1/250s etc.

A variants can call for the ISO to match the shutter speed number exactly, e.g. ISO 100 / shutter speed 1/100s etc.

With these conditions your photo should be correctly exposed for the amount of incident light falling on your subject (search boards.ie for the difference between incident light and reflected light).

Part 2 - Using the S16 rule for correct exposure

Your friend is simplicity so here is my patented four part process...

1. Set your ISO to 100 and your shutter speed to 1/125s
2. Choose the appropriate lighting condition for your subject from the list below (this is the hardest part and remember, practise makes perfect)
3. Set your aperture to the f-stop given for your specific lighting condition
4. Press the shutter release button, aka take the photo

The 5 basic lighting conditions

• there is clear sun and sharp shadows (Toto, I've a feeling we're not in Ireland any more), use f/16
• there’s a slight overcast and the shadows are a bit fuzzy (getting closer to Ireland), use f/11
• it’s overcast and there are no shadows (ahh, Ireland…), use f/8.0
• it’s really overcast and probably going to p*ss rain (uugh…Ireland in the summer), use f/5.6
• I’m in the shade (sarcastic comment due in article 2.0), use f/4.0

And that's it.

If you want to know more and get more involved keep reading, if not grab your camera and start snapping!

Part 3 - How the S16 rule works

Basically:

1. The f/16 starting point detailed above gives correct exposure, that we take for granted.
2. Each subsequent lighting condition gives us half the amount of light as the previous condition, e.g.
   
   A slight overcast condition gives half the light of full sun, an overcast condition gives half the light of a slight overcast etc.
3. The subsequent changes in aperture let twice as much light into the camera and so we continue to get the correct exposure.

Part 4 – adapting the S16 rule for specific requirements

Be warned…this part gets complex…

So the S16 rule gives us specific conditions and settings but what if those settings don’t meet our requirements?

Let’s say we are taking a landscape photo in foggy, overcast conditions. The S16 rule says that your aperture should be f/5.6 but this isn't suitable for landscape. Understanding how to bend the rule means looking at the basics a little (lot) more…

Aperture…the elixir of life...or at least of cameras

Aperture sizes are referred to as 'stops', that's where we get the term f-stop, e.g.

f/16 is an f-stop, f/11 is another f stop etc

Moving a full f-stop means the aperture doubles or halves in size, depending on which direction you are changing, e.g.

a change from f/16 to f/11 is one f-stop, f/11 will let in twice as much light as f/16 (yes, the smaller the number the bigger the opening, but the reason is for another article, for now just accept it)

The chart in Part 2 changes one full f-stop between each condition. As the conditions deteriorate incident light gets halved and the lens lets in twice as much light to compensate…the net result is the same level of exposure each time.

Shutter speed and ISO, aperture’s partners in crime

Like f-stops, changes in ISO and shutter speed result in more or less exposure for the image, e.g.

- a shutter speed of 1/125s will only let in half the light of 1/60s

- ISO 100 will absorb (at least the camera sensor will) half the amount of light as ISO 200

Unlike aperture, there’s no chart as such for shutter speed or ISO, it’s just simple maths.

Bending the S16 rule

Now you understand the rule, you can start to change it. This process is a little more complex that simply obeying it, but here we go…

1. Set your ISO to 100 and your shutter speed to 1/125s
2. Determine the appropriate lighting condition for your subject from the list
3. Set your aperture to the f-stop given for your lighting condition
4. Decide on the f-stop you would actually like to use, in the landscape example we might want to use f/11 to ensure a good depth of field
5. Count the amount of f-stops between what the S16 rule says and what you have chosen to use and also decide if the change lets in more or less light than if we followed the S16 rule. In our example the S16 rule says f/5.6 and we are using f/11, a change of two full stops and also less light than expected (1/4 the light to be exact).
6. Determine the change required to the shutter speed or ISO to compensate for this loss in light. In this example f/5.6 to f/11 is two stops so we could change:
   - the shutter speed from 1/125s to 1/30s (this is doubling the shutter length twice, from 1/125s to 1/60s and then from 1/60s to 1/30s, each change compensating for one of the two changes in f-stop)
   - the ISO from 100 to 400 (this is doubling the sensitivity of the camera sensor twice, from 100 to 200 and then from 200 to 400, each change compensating for one of the two changes in f-stop)
   - combine a change from each so the shutter speed changes to 1/60s and the ISO changes to 200, each change compensating for one of the two changes in f-stop)
7. Press the shutter release button, aka take the photo

This example assumes we have a desired f-stop for our image but it could just as easily be that we have a desired shutter time instead. In this case we’d use the S16 rule to determine our start point, set our shutter to our desired speed, calculate the difference in light this results in and change the f-stop accordingly to compensate.

It’s my belief you should really only change the f-stop or shutter speed. Changing the ISO should be the last port of call and only used for very difficult lighting conditions, traditionally because it introduces a lot of noise above ISO 800 but more lately, with better sensors in DSLRs, because simply changing the ISO just doesn’t increase your knowledge of photography workings as much as changing the aperture or the shutter speed.

The final stage, getting thoroughly complex…and slightly confused…or even bemused…

If you’ve read this far you either understand everything to date and want to know more, or you are suffering from serious insomnia. Either way, let’s continue.

Between each full f-stop there are half stops and even third stops. These can be used for tweaking your choices if the results are not exactly what you had in mind. For example, let’s say we want to take a seascape in overcast conditions. The S16 rule suggests these settings:

- f/5.6, shutter speed 1/125s, ISO100

We already know that f/5.6 is not good enough for landscape. We want to push the boat out (boat…seascape…get it?…never mind) and go for for f/22, five stops away with less light:

- f/5.6 – f/8.0 – f/11 – f16 – f22

This means we have to increase our shutter speed to 1/8s:

- 1/125s – 1/60s – 1/30s – 1/15s – 1/8s

This shutter speed is a little slow, for this image we don’t want to introduce too much blur in the water so we increase the shutter speed back to 1/15s by increasing the ISO to 200. This is still a little too slow but we want to keep noise to a minimum and aren’t prepared to go above ISO 200. What do we do?

We compromise, something we have to do in photography a lot. Instead of a full stop back to f/16, we only change one third of a stop to f/20. Unlike a full stop that limits light to half, we’ve only taken a sixth away and can compensate with a smaller change to our shutter speed to 1/20s and no change to our ISO.

Now we can see how, using nothing more than a simple rule that offers a basic starting position and a notepad and sharp pencil for some simple calculations, we enter the world of creative exposure control with full control in almost every lighting condition we find ourselves in.

...at least I think I'm right anyway...

Steve

secman

Just recently got a nikon d7000 having been away from photography for 25years. Over the last few days i have been downloading the EV charts and the exposure tables. Had forgotten them, but slowly coming back to me . Thanks for reminding me about the sunny f 16 rule. Looking forward to weekend to try it out and stay away from auto settings, practice practice, shoot and shoot again. Great thing about digital is you can experiment all you like and see the results immediately, unlike film !

Thanks again

secman

DaireQuinlan

or... 99% of the time your camera will produce a perfectly exposed shot with its inbuilt meter. The only important thing is knowing when it won't (dark/light coloured/backlit subjects) and how best to compensate for that.

secman

DaireQuinlan wrote: »

or... 99% of the time your camera will produce a perfectly exposed shot with its inbuilt meter. The only important thing is knowing when it won't (dark/light coloured/backlit subjects) and how best to compensate for that.

As a matter of interest Daire, % wise how much do you shoot, Auto, Apperture priority, shutter priority or manual ?

The main reason I am trying to use the EV charts etc is to get the grey matter working again in this area, if i stick it on Auto or Scene mode i feel i would not be learning anything ?

Secman

DaireQuinlan

secman wrote: »

As a matter of interest Daire, % wise how much do you shoot, Auto, Apperture priority, shutter priority or manual ?

The main reason I am trying to use the EV charts etc is to get the grey matter working again in this area, if i stick it on Auto or Scene mode i feel i would not be learning anything ?

Secman

probably 99% aperture priority with exposure compensation where necessary in any camera I have that actually HAS some form of automatic exposure. Otherwise I have an external meter and I've had to rely on sunny 16 (or more sunny 11 in Ireland I find) once or twice when I've forgotten the meter or my in-camera meter wasn't working or ran out of batteries.


I'm not saying it's not useful, I'm more taking issue with the title of the thread. A beginners best bet to getting correct exposure is to allow their camera do its job :-D

.Longshanks.

I've heard on the Sunny 16 rule but have never used it or felt the need to figure it out. 99% my camera is AV and M the other 1%.
When in AV it does the math for me

Steve Reddin

DaireQuinlan wrote: »

A beginners best bet to getting correct exposure is to allow their camera do its job :-D

For me, a camera on auto or semi auto will, at best, take an average photo. I'd certainly disagree that 99% of TTL metering results in a perfectly exposed photograph but if you're happy with your resulting images then I'll not argue with you.

Maybe I should have titled this 'A beginner's guide to learning about exposure' to avoid this 'confusion'; my aim was to inform a beginner how to move from auto mode to complete creative exposure control in a step by step process that hopefully makes sense.

Steve

DaireQuinlan

Steve Reddin wrote: »

For me, a camera on auto or semi auto will, at best, take an average photo.

If you're talking in general then that's just nonsense. If you're talking just about yourself then you're doing it wrong

dirtyghettokid

Steve Reddin wrote: »

For me, a camera on auto or semi auto will, at best, take an average photo.

i wouldn't agree with that .. aperture priority with exposure compensation when needed will give you pretty much what you want!

Steve Reddin

DaireQuinlan wrote: »

If you're talking in general then that's just nonsense.

No, it isn't.

DaireQuinlan wrote: »

If you're talking just about yourself then you're doing it wrong

No, I'm not, I know my way around a camera.

So, there you go, I think full control gives the best results and will advise accordingly, and you don't...world keeps on turning...

Steve Reddin

dirtyghettokid wrote: »

aperture priority with exposure compensation when needed will give you pretty much what you want!

...unless it doesn't give you pretty much what you want...being that what people pretty much want differs hugely by person and context...

Again, my approach is different and I would think that it's OK to suggest it as an alternative, I'm not forcing it down anybody's throat, don't use it if you don't feel your work needs it.

magicbastarder

but if you're shooting manual, do you use the camera meter's input and compensate accordingly? because that's what most people do when they use auto metering - i shoot on aperture priority and use exposure compensation in trickier lighting situations.

DaireQuinlan

Steve Reddin wrote: »

DaireQuinlan wrote:

If you're talking in general then that's just nonsense.

No, it isn't.

What, you're honestly saying that, in general, "a camera on auto or semi auto will, at best, take an average photo" ? That's complete balderdash. It's total nonsense. You're saying that EVERY SINGLE PICTURE EVER TAKEN EVER IN THE HISTORY OF PHOTOGRAPHY with the camera on auto or semi auto is, at best, "average" ? I'm tempted to employ the rolleyes smiley here, but surely you can see what sort of claptrap that is ?

Steve Reddin

DaireQuinlan wrote: »

What, you're honestly saying that, in general, "a camera on auto or semi auto will, at best, take an average photo" ? That's complete balderdash. It's total nonsense. You're saying that EVERY SINGLE PICTURE EVER TAKEN EVER IN THE HISTORY OF PHOTOGRAPHY with the camera on auto or semi auto is, at best, "average" ? I'm tempted to employ the rolleyes smiley here, but surely you can see what sort of claptrap that is ?

Good heavens, will you relax...

To explain what I meant, and I do apologise if my original articulation maybe wasn't as strong as it should have been, I'll reword what I said to 'a camera on auto or semi auto will, more often than not, take an average photograph'.

There have been great images captured on auto, semi auto and even with instant cameras, I know that. That being said, I think full manual control offers the better option of achieving an above average photograph and I think understanding and using full manual control gives a photographer more options.

You don't think that, which I get, I truly do but my initial post objective wasn't to have a tangent row, so relax with the CAPLOCKS, take your photographs in the way that suits you, I'll do the same and everything will be just fine.

Steve

DaireQuinlan

Steve Reddin wrote: »

Good heavens, will you relax...

To explain what I meant, and I do apologise if my original articulation maybe wasn't as strong as it should have been, I'll reword what I said to 'a camera on auto or semi auto will, more often than not, take an average photograph'.

Well, again, this is just plain wrong. Maybe in your case your camera "will, on auto or semi auto, more often than not, take an average photo". But I think that has more to do with you not using your camera properly than anything else. But to extrapolate that out into a general case is, as I've said about three times now, nonsense.

Steve Reddin

Fair enough

ImagenEstilo

Hmmm! Interesting.

Personally, I shoot manual 100% of the time, there is no 99%, it is 100% all the time. So Steve I would agree with you on manual giving you more control. It does, especially when using on or off camera flash. It also makes you think harder as you constantly have to adjust. If I was to choose any other mode it would be aperture priority but in my case (I live on the costa del sol) sometimes I hit the upper limit on my shutter speed when at wide apertures, so I get over-expoure.

So for me, manual does it, constantly thinking, constantly changing, no need to faff around with exposure compensation which on Nikon will affect your FEC also (not on Canon though).

I wouldn't agree with the auto or semi auto taking average photos. That is just incorrect in my opinion and I dont need to explain why. Another reason I would steer clear of a semi auto mode is it will make my post processing that little more time consuming as each exposure will be slightly different and you can't use batch adjustments as easily.

A question though, when you look at say aperture priority, you have control over your aperture and you fine tune exposure using your EC. This is two controls you are using. Manual is also two controls Aperture and SS. EC does not come into it on manual once you are familiar with your camera. So why not go full manual anyway is my question??

Dave