You can see light merely as sufficient level of ‘illumination’ but over time you will begin to see that it’s the quality of light that matters most, not merely the quantity.
But without the right ‘quantity’ you don’t have an image. So let’s deal with setting the ‘exposure’ and getting enough light into the camera, and onto the sensor so that you have an image.
This article will deal with the camera end. And since we often have no control of the light around us, being able to control the exposure with the camera is a vital and creative step that’s often overlooked by simply letting the camera do all the work.
If you don’t know how, or why, to take control of your camera, I encourage you to get some hands-on training. At Bring Your Own Camera, we have a range of fun and engaging workshops and photo walks that will show you the value of making your own choices.
So how you do set your own exposure?
Your camera has three interlocked controls that ensure enough illumination reaches the sensor to expose an image. Shutter Speed, Aperture, and Sensitivity (known as ISO). This combination is often dubbed ‘the exposure triangle.’ The Bermuda triangle, while similarly mysterious, was taken.
On your camera’s manual controls, they are listed as Tv (time value), that’s your shutter speed, Av (aperture value), that’s your f-stop, and ISO. ISO replaces ASA (American Standards Association) and is a nickname for the International Organization for Standardisation. It refers to the arcane measurement of film speed, but since that’s a gross representation of sensitivity, it works identically for either a sensor or a piece of film.
So, ISO, Av, and Tv. This controls the amount of light entering the camera. Change one, and the other 2 have to shift to rebalance the equation. Let more light in by opening the aperture, and you can make the shutter speed faster – you’ll get the same amount of light in.
High shutter speeds freeze action. Smaller apertures (higher f/stop numbers) means more of the image, from front to back, is in focus. Lower ISO means less noise or ‘grain’ (grain is only applicable to film and looks a heck of a lot better than noise) in the image. ‘Push’ the ISO, perhaps move from 800 ISO to 6400, and your sensor is more sensitive to light, meaning you can choose faster shutter speeds and/or a smaller aperture.
For example, you may want to move from f/2.8 to f/16 so there’s a lot more in focus. To get a proper exposure you may have to increase the sensitivity, or leave the shutter open longer to accommodate that move from f/2.8 to f/16.
A good exposure, i.e. enough light, means you get a properly exposed image. But again, this is the quantity of light, not the quality. We need a basic quantity and the good news is that a modern camera has a very good computer on board that just sits around working out how to get a ‘proper’ exposure and get the quantity needed.
That, of course, means the camera ‘averages’ what it sees and decides how to balance the brightest and darkest parts of the frame to create an 'acceptable' exposure based on quantity.
If you like food as much as I do, the average is expedient but frequently disappointing.
For all its clever technology, your camera makes a few simple judgments, sometimes factoring in what you’ve focussed on, and what ‘scene mode’ or picture profile you’ve selected. But at the end of the day, it’s usually making a center weighted average. You can tell the camera to favour the entire frame (average), give preference to the middle of the frame (centre weighted average) or take a tiny portion of the middle of the frame (spot meter).
Some higher end DSLR and mirrorless cameras take into account where in the frame you are focussed on, or if in 'face detect mode' who you are focussed on. RTFM.
What you might not realise is that the camera mostly has no idea what it’s actually measuring the exposure of.
It’s unable to know if you’re pointing at shiny metal or a dark matte substance. In fact, your camera assumes that what you’re pointing at is 18% grey a.k.a. middle grey. That’s the average reflective value of human skin. Mostly pale skin. Ok, white people. Yep. That’s the minority of people on the planet – but when metering for cameras to judge exposure was invented, pictures of white people were considered the most common thing to set the exposure for.
Quick tip – for darker complexions, set your exposure for the highlights. That means you measure your exposure from the brighter ‘highlights’ on darker skin. For albinos, look for the darker areas or the transition areas between bright skin and shadows.
If you are shooting RAW, you can push your exposure in the post production process (Lightroom etc.) and the relatively small range of exposure between skin tones is easily corrected – so don’t overthink this one.
I and my dinosaur brethren come from a time when film and video had a very narrow exposure latitude (the range of tones between dark and bright). Cameras had a tiny matchstick-like bar that waved inside the viewfinder to suggest exposure. We had less tools, less accuracy, and a smaller margin for error. But, that experience made us better at measuring and setting exposure.
It’s good practice to be able to know what the camera is doing, or what you need to do, especially when you can’t reshoot and you need to get it right. No one wants to stand around forever while you try to figure out how to cope with dark faces, bright backgrounds and possibly the one albino I met on a Fijian island next to her deliciously dark family. True story.
So what happens if what you’re pointing your camera at isn’t human skin? Well, the camera takes the brightest value it sees, compares it to the darkest value available and arrives at a compromise. This works well enough and often enough that we generally get a result that’s workable. But if you want to have more control, you can take a few steps.
You can use a separate light meter – this allows you to put your meter where the light and subject is – exactly at the spot you want to expose correctly. Professionals are split right down the middle on this one. Now that your camera can show you a picture on the screen, and a histogram (enable it in the info or view settings on your camera) that charts the actual exposure from dark to light of your image – why do you need to futz with a meter that might cost the same as a camera?
The other side of the argument is that electronic screens and viewfinders are notoriously over exaggerated to always make a ‘pretty’ picture. You simply can’t trust what you see.
I think that fiddling with a light meter is actually kind of fun, but adds complexity to your shooting, no matter how proficient you are with it. I don’t care either way until you start spooking your subject by rushing up to them and waving a device within inches of their face.
Models take an even dimmer view of metering the reflective values of their bust. Before your laugh (or slap), a large rounded area of bare skin has a terrific range of values from dark to white. Curves make brighter highlights than flat faces.
And, of course, we don’t all come in middle grey or have the same reflective values of skin. Matte makeup can change the exposure reading. Sweat too. A hand held light meter ignores the subject, it’s pointing towards where the light is coming from (and you’re holding it in the same area where the light is doing its thing). It has a little dome that takes an average of the light at that point.
But you can use your camera like a light meter too.
If you’re trying to accurately meter 18% grey, you can buy a ‘grey card’ for $10 or get one of the new pop out reflectors that has grey on one side (for exposure), white on the other side (for bouncing light). Use the grey side for setting white balance. White balance is crucial if you are shooting JPEG or video because the white balance (colour temperature and the balance between green and magenta) is baked in. Good cards have some fine markings that allow you to nail your focus.
I put one of these gray cards on a stand exactly where my subject will be standing (mark the spot on the floor with some tape) and I can set my exposure and focus before my subject is in front of the camera.
You’ll put your subject at ease and look a lot more pro (both are linked) if you’re ready to shoot with less fussing around. At the very least you’ll have a starting point close to perfect that requires just a little adjustment – and you will have already dealt with the stress of ‘why is the picture black…etc.’ without an audience.
If you don’t have a grey card or pop out reflector version of the same, use the back of your hand. It’s human skin (for most of us). Set your camera’s meter mode to ‘spot’ and it will measure the light in a very tight area – typically a 6-degree angle coming from your sensor to whatever is in front. Spot metering is usually metered at the very centre of the frame. Check your camera’s manual if you’re not sure (RTFM? Surely not! LOL)
Grab your camera, walk to where the light is that you are photographing in, stretch out your hand, and measure the exposure off your hand. Angle your hand to see the highlights (the bright light) rather than the shadows. If your hand is shadowed when you set your exposure, you will overexpose the brighter parts of the frame.
Remember, put your hand (or grey card) where the light is – where your person will be standing, or right in front of the object you’re shooting. Dark coloured statues and sculptures can be tricky to meter sometimes, so the ‘hand trick’ will give your camera something predictable to meter.
But if modern cameras are pretty good at working out the exposure, why would I want to do it manually instead of letting the camera do it from shot to shot? Tiny changes in what the camera is looking at can change the values metered. If you photograph a person who is moving (even a little) you might get slightly altered exposures from frame to frame.
I like to meter it once, take a couple of test shots, then lock the exposure. This means switching to M (manual) on the camera controls. This way, I know the camera isn’t going to flub the exposure because my subject moved and the camera got swayed by a change in what it’s looking at. Clothes or a lot of hair flying about can easily change the ‘exposure’ average the camera is seeing. Turning the model’s face into or away from the light changes how much bright skin is or is not influencing the exposure.
It’s a lot easier to post produce your images when they all have a consistent exposure.
Imagine a model wearing black on a black backdrop (or the same with white everywhere). The camera is going to average all that out and either expose too much or too little. And the face is going to get the wrong exposure as the camera is influenced by all that dark or light.
I measure off the face or a grey card, and I know I’ve got it right. Locking the controls means that as I move the camera or the subject moves, I’m not getting incorrect readings or inconsistent exposures.
In the middle of a shoot, it’s easy to glance at the screen on your camera and think it looks ok. Those screens are not accurate, and very ‘the glass is half full’ optimistic. Check your histogram. If you set your exposure properly, it’s one less thing that’s going to get away from you as you shoot.
And it’s not just about photographing people. Judging your own exposure is a vital part of landscape photography. Try deliberately underexposing a scene and you’ll discover a rich hue of colours in the sky and clouds that ordinarily get washed out by overexposing the scene.
Remember, 'average' exposure gets rid of the extremes, and sometimes that’s where the interesting parts are. You don’t want all your food to be hamburger, do you? How about a rare steak once in a while? Or a charred piece of BBQ pork? Notice the average fast food place serving any of that?
If you need help learning how to work the manual controls of your camera, try some of our photography training, or get hands-on with the latest photography-related software to finesse your images after you’ve shot them. We’ve got the training you need and we know you’ll enjoy it.
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