HOW TO EXPOSE YOUR IMAGES CORRECTLY

INTRODUCTION

“How do I expose my images correctly?”

This is a problem that a lot of new photographers seem to encounter, and they frequently ask the same question: “what settings should I use to correctly expose my pictures?”.

Well, unfortuneatly it is not an easy question to answer, except to say this:

There are no wrong settings, only poor interpretations of the scene.

Having been very clever and said that, I must add that there are things that you need to understand about cameras and light to get the best possible results. So hopefully I will cover enough stuff in this month’s tutorial to answer all your questions and give you a much greater understanding of how your camera works.

I feel personally, that B&W photographers get their heads around exposure much easier because they think in terms of Black and White [which is how your camera thinks]. Colour photographers can get all caught-up in that icky colour stuff which is irrelevent as far as your camera is concerned. It doesn’t care if green is brighter than blue.

So for the purposes of easier understanding, try to start thinking of exposure in terms of Blacks and Whites.


HOW YOUR CAMERA “METERS” A SCENE

When you point your lens at a scene your camera takes in a lot of information, and it has to decide what to do with this information, and it has to do it very very quickly.

It would be nice to think that our cameras are really really clever, but they are not, and in fact they are a bit lazy.

“Why is my $5000 camera lazy, Byron?” I hear you ask.

Well its like this, your camera will look at the whole scene but will only do a metered reading of a certain section of the scene [depending on the metering method you have selected on your camera]. Your camera then calculates the most suitable exposure settings based on information gathered from that region. Generally, most cameras do not do metered readings of 100% of your scene. See? – that’s just lazy!

What it does is this…

Your camera knows that if the exposure settings [f-stop + shutter speed + ISO/ASA] resulted in the average of the metered values in that region being the same as the values metered from a piece of grey card, then the rest of the image should be ok.

This magical grey card is known in the industry as “18% Grey” – because brightness levels are measured on a sliding scale from white to black, and that particular amount of grey is equal to 18% of black on a white background.

Geek Alert: this is a bit lighter than the lightest grey [24%] Fill Colour or Text Colour in MS Excel.

This is a typical Exposure Card, the main area under the target is 18% Grey:

What you do with these cards is – you point your camera at the 18% Grey section to take a metered reading [using the prevailing light], then manually enter those settings into your camera and fire away. Everything should now expose just fine.

Or you can let your camera do it for you.

A quick word about metering equipment…

Today, most cameras do a damn fine job of metering your scene, but if you want to do a really accurate reading you generally need to use a Light Meter. Professionals and Studio Photographers regularly use Light Meters because they need to have very accurate control over their light.

Some different types of Light Meters for those of you who like to do things the old fashioned and really accurate way:

Now back to the topic at hand…

If you are really tricky, you can use this knowledge to expose your images using what is called the Zone System for metering your scene… but you don’t really need to know about that [that, and I still don’t fully understand it!]

So, to recap…

  1. Your camera exposes every scene so that the predominantly brightest part of the metered region will appear as bright as a card of 18% Grey.

Its important to remember this bit kiddies, it is what your camera does every single time you press that button.


HOW TO PHOTOGRAPH SNOW

Everyone, and I mean everyone screws this up the first time. Even me.

Ok, I didn’t because I knew about this.

Ok, I did really because I wasn’t thinking at the time. [come on, it was the first time I had seen a glacier, ok?]


[Image posted to demonstrate certain points only. No invitation to critique should be inferred by its use.]

Trust me, the snow was waaaa-a-a-aay whiter than it appears in that image. But, I digress…

When you go to the snow, what do you see?

White, lots and lots of W-H-I-T-E! Everywhere.

Its also very very [v-e-e-e-e-r-y] bright.

So naturally, what would we do with a very bright white scene?

Come on, you all know what to do!

What does the iris in your eyes do when you see something really bright? – it gets smaller to stop so much light coming in!

So – what should you do with your camera when you see lots and lots of bright white snow? – Logically we would think “oooh, I need to under expose this or its gonna be alllllll white”.

Yep, uh-huh, ok.

W-R-O-N-G

Remember our little talk a few minutes ago about 18% Grey and how your camera is really lazy… well this is one of those times you need to know about this.

Your camera has looked at the snow and gone “holy shit, that’s a lot of white, I need to expose it so it looks like 18% Grey, then everything should be ok”

Can you see the problem here? Yep – the snow will come out grey, not lovely and white. The camera wants to under-expose which will make the white snow darker.

So what do you really need to do? – You need to over-expose the shot one, two or more stops. I tend to put my camera on Exposure Bracketting at half-stop increments and let it take 5 or more quick shots going all the way to 3 Stops over-exposed.

This is counter-intuitive, but when you understand what your camera is doing – it actually makes sense.


HOW TO PHOTOGRAPH STUFF AT NIGHT TIME

Dark scenes are also misleading. We are used to everything being exposed, and we often try to do the same at night, but at night that is just not possible – there is way too much darkness. Without serious lighting systems you just can not fully expose a night time scene.

Just get used to it, ok!

We also forget that there are lights everywhere – street light, car lights, lights on buildings, advertising signage… lights are everywhere, and they are much much brighter than the darkness [but not quite as bright as the sun].

So what happens when you ask your camera to expose a night time shot?

Your camera goes “geez louise its dark, but if I make the darkness as bright as 18% grey, then everything else should expose ok” … [black being the predominantly brightest part of your scene] – so you press the shutter and get the washed out milky piece of rubbish with no blacks and some very over-exposed whites. Yuck!.

Have you worked this one out yet kiddies?

Uh-huh, you need to under-expose your night-time photography. A lot.

You need to tell your camera “No, I want all the black stuff to be really black, and I only want the bits that are well lit to be exposed properly!”

Anything down to 3 Stops under-exposed from your camera’s original metered readings will usually do the trick.

Another one from my portfolio:

[Image posted to demonstrate certain points only. No “invitation to critique” should be inferred by its use.]

This is the same shot of cars driving past at night, copied rotated and pasted to form an abstract image. Manually exposed @ F11 & 2sec [approx]. Majorly under exposed so the dark areas are beautifully black which has enhanced the colour saturations. It was always a given that no matter how much I under-exposed the scene – the colours were always going to come out ok. The colours here have not been done in post-production.


EXPOSE FOR HIGHLIGHTS, or EXPOSE FOR SHADOWS

But there is another way to expose your images, and it is as old a technique as the Sunny 16 Rule…

Instead of trying to expose your whole scene perfectly … choose one extreme or the other and bugger the rest. Meter your scene on either the brightest section or the darkest section and go with that. You need to use your “Spot Metering” function not Centre Weighted or Scene Average metering.

To Photograph Snow… you want to get a metered reading on the darkest part of the scene. This means that shadows will be nicely exposed with good detail, and the snow should come out white since you are exposing more than you would if your did a metered reading of the white snow.

To Photograph at Night… you want to get a metered reading on the brightest part of the scene. Find a street light, use your Spot Metering function and get a good reading on that bright light, this will expose most of the street lights quite nicely with some detail, while making your dark areas lovely and black because you are exposing less than you would if you did a metered reading of the dark areas.

Just remember this rule:

“If its white – meter on black, if its black – meter on white.”

This white-black/black-white rule is handy to remember if you are ever shooting a wedding… Don’t do a Spot-Metered exposure reading on the Bride’s Dress because it will turn out grey, and the Groom’s black Tuxedo will just be a mass of black and contain no detail. Do your reading on the Groom’s Tuxedo. [or use an 18% Grey Card]

You can use the same principle of exposing for Highlights or Shadows when shooting indoors where the light is not perfect. Don’t expect to expose the scene perfectly like you would outdoors, but figure “some areas are going to be dark, and I am ok with that!” then use the above technique.

Here is another one from my portfolio:


[Image posted to demonstrate certain points only. No “invitation to critique” should be inferred by its use.]

Shot on Kodak Hi-Speed 6400ISO film. Manually exposured @ F3.5 / 1-60sec. I knew I could never fully expose this scene, so I figured that F3.5 & 1-60sec would expose some of the scene and I would be happy with that! I knew that the black regions would be very black and that was my primary concern.

Here are three more examples from my own portfolio. All taken at exactly the same location, same time of day, with some Levels adjustment in Post Production – but otherwise no other changes…

Exposed for Highlights [the window in the background]:

[Image posted to demonstrate certain points only. No “invitation to critique” should be inferred by its use.]

Exposed for Scene Average:

[Image posted to demonstrate certain points only. No “invitation to critique” should be inferred by its use.]

Exposed for Shadows:

[Image posted to demonstrate certain points only. No “invitation to critique” should be inferred by its use.]

Look at the difference between these three images. Believe it or not – its the same wall in the background of all three images – except one appears black, one appears grey, and one appears white…

It is a white wall, but I can make it black by metering on something brighter [like the sun coming in thru that window] which forces the camera to under-expose, and thereby darkens the wall making it black. In the last photo, I wanted the wall bright white with no detail – so I knew I had to over-expose the shot. Easiest solution – spot meter on the darkest part of the room!

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