Ham's Crash Course Into Photography: Part 2 - Good Light & Exposure

    Good light? Huh?

    Ok, so the word photography comes from the merging of Greek words. Photos (meaning "light") and Graphos (Meaning, "To draw" or "drawing"). So photography literally means "drawing with light" or "light drawing". So light is an essential ingredient into any successful picture. However, not all light is created equal. Some forms of light will help to improve your image, (think pink fluffy clouds at sunrise/sunset) while others can make your shot look worse, (think direct sunshine making everyone in your portrait looking all "squinty").  Whether the light is good, bad, or average, all light has three main characteristics that you need to know:

    1. Colour. Are you shooting in a golden sunset? Fluorescent office lighting? Under a red neon sign? This changes the colour "cast" of everything the light hits. Let's say that your model (or subject) is your 8 year daughter, and she's wearing a white dress. If you photographed her in each of the above lighting conditions, her white dress would look golden, green, or red respectively in each of these conditions. Photographically, this could mean she's enjoying the sun and looks radiant, looks green/sickly indoors, or just plain unnaturally red, perhaps in some sort of theatrical production (or red enough to appear demonic) under the neon sign.
    2. Intensity. How much light is it? Are you lit by a single candle or out in full midday sun? In daylight conditions, any camera will work well. In really low light situations, you might need a different approach, more equipment (like a camera flash), even completely different equipment (like studio lighting), or a combination thereof, to take a good photo in difficult conditions. Intensity is also affected by the distance between source of light and the subject, and what the light has to pass through to and/or bounce off to get to the subject and then into the camera.
    3. Direction. Is the light coming in from above, below, left, right, in front, or behind the subject? Is it direct, hard light with hard-edged and deeply contrasting shadows? Or is it diffuse light, where there mightn't be any overt shadows at all? These give the photos completely different feels, or contexts. You might want to create a hard-edged silhouette of an elephant walking across the African plains with the sunset behind it, or soften the wrinkles on a woman's face by choosing a softer, more diffused source of light. Both techniques use opposing styles of light to improve the shot.

    A little exercise to demonstrate the difference between "good" and "bad" light.

    If you shoot the same outdoor scene at different times of the day.  Say, every hour or two from dawn to dusk, and even beyond into night. You'll see that there are times of day which the picture looks better than the others. You might not be able to put your finger on why just yet, but have a go and see which one you like the most. If you're like most photographers, you'll probably prefer the shots around dawn and dusk. These times are called "The golden hours" which are heavily used by landscape photographers. Simply because there isn't a flash in the world capable of providing enough light to control the lighting for then entire visible land area.

    Golden hours usually occur when the sun is closest to the horizon. So the low angle of the light reduces the harsh glare by forcing the sun's rays to go through the atmosphere diagonally, and the angle to the ground accentuates the shadows (which are just as important as light in a good photo) because it gives the impression of texture (and third dimension) on what is effectively a two-dimensional image. Perhaps most importantly, golden hours bring some absolutely gorgeous colours to a scene in the right weather conditions.

    Good light means different things in different contexts, and it really depends on the type of photo you're chasing.  Honestly, there's no such thing as "bad" light, but there is certainly light which makes taking great photos more challenging, so pick your battles to increase your odds of success. That isn't to say that you can't take good photos outside of the golden hours, but to do it well, you need to be more creative, solve issues like glare, harsh shadows, or even things like crowds and traffic at livelier times of the day.

    The camera and "getting the light right" - Exposure:

    It may shock people, but while a camera has some similarities with the human eye, it doesn't see things quite like we do. Whole books have been written on this subject, trying to condense all that down is a challenge, but I'll give you the broad strokes.

    If you're not using a flash, and already know how to focus a shot (we'll keep it simple for now) there are only 3 main settings that control the apparent exposure (which the overall recorded brightness/darkness of the image). Note the word recorded. That's important. You see, two settings regulate the light reaching the sensor, and the third is applied to the electrical signal coming out of the sensor, and adjusts how that signal is interpreted before writing the image data to your memory card.

    I will go onto the "traditional explanation" of the exposure triangle... so you know what it is, and despite the minor errors it teaches people in how it works... it really is a useful piece of information. However before going into that, here's a rather entertaining video on why ISO is the often-misunderstood problem child of the exposure triangle.

    What the heck is a "stop?"

    Dialing in the huge differences between the darkest and the brightest values of each setting would be very slow and painful process if you had to crank each dial for minutes, perhaps hours on end. So they've used an exponential means where each setting either doubles, or halves the values beside it. Each time you double or halve a setting this is referred to as a "stop".

    For example: Lets say your shutter speed is at 1/100th of a second. One stop faster, it'd be 1/200th of a second (half as long... or twice as fast), two stops over, it'd be 1/400th. Six stops over from 1/100th is 1/6400th of a second. Imagine what photography would be like without this doubling/halving "stop system"... having to turn the dial hundreds or even thousands of times to reach a desired setting, you'd spend an hour specifying all three settings. That wouldn't be fun!  Of course, most cameras offer the option to adjust the settings in half-stop increments, or even thirds for greater control. Still... if each click on the dial is 1/3rd of a stop... you only have 18 "clicks" on the dial to go from 1/100th, to 1/6400. The dial may be set up to have anywhere between 3-12 settings (or clicks) for each full rotation. So a few turns can get you from the top values, to the bottom in mere seconds.

    Understand that the three settings can work in unison to brighten or darken the final recorded image, or be individually used to compensate for changes in one or both of the others.

    Important: There are many ways to mix these three settings to get a photo of an apparent equivalent brightness (exposure) but each shot can look very different from one another. Here's my exposure triangle cheat sheet. On each corner of the triangle, you'll find the name of the setting, and on each side of that name, you'll find the effects of increasing or decreasing that particular setting. Most effects can be used creatively to improve images, depending on the situation, and whether or not that's how you want the shot to look.  However, there are a few downsides that I added in red.. because they're usually considered to be universally irritating, or lower the quality of the recorded image.

     

     

    A brief run down of each setting:

    1. ISO (sometimes called "sensitivity", and on old film cameras, occasionally ASA which was merged with ISO in 1974):
      • This is usually the first, or last setting the photographer adjusts when taking a shot. Generally, you want to keep this number as low as possible to keep your photos free of "noise" which is a grainy effect that makes your photos look dirty. As you turn this setting up on digital cameras, the noise becomes exponentially more noticeable. At the lowest end (usually 100), it'll be difficult/impossible to see. At 400, you'll start noticing it. Beyond that, it may seriously start negatively impacting the quality of your image, but this depends on the model of your camera. However, as your shooting conditions get darker, you probably need to start cranking that setting up to some sort of compromise that suits your intended image. Smaller cameras, and/or cameras with higher pixel counts will suffer from more noticeable noise at lower ISO settings, and get worse than other models as the settings are raised from there. This is one of the biggest differences between compact cameras and more professional models
      • In the old days of film based photography, certain types of film were used in bright conditions, and others were treated with chemicals differently so that the film would work with less light (or be more sensitive). Most films started at ISO 100 and worked in bright daylight, and they went up from there to 3200 and beyond for extremely dark conditions. Each step of sensitivity doubled the sensitivity of the previous film, so they doubled ISO number to match. The range typically went from 100, 200, 400, 800, 1600, and 3200 (maybe further). If you needed to change the ISO for shifting shooting conditions, you had to change to an appropriate film to match it. Which became expensive as you had to keep buying the right films. "Sensitivity" as a concept has persisted into the digital photography world, but is fundamentally wrong when considering the technology that lies within a digital camera. Strictly speaking, changing the ISO setting on a digital camera does not need a "sensor replacement" but it refers to a process of amplifying the signal coming from the sensor. The sensor itself doesn't suddenly get better at detecting light so sensitivity is "wrong", but rather the computer says, "Well, whatever the amount of light is recorded, I'm going to register it as a brighter value". Interestingly, sensors make mistakes, and much like a stereo turned way up, you'll get that static hiss coming through your speakers. However, instead of an audible "hiss", noise presents itself in a different way in an image. As the noise increases, the image starts to have a similar grainy effect to high ISO films, mixed with randomly coloured dots here and there, that makes details harder to see. High end digital cameras these days can go to ISO settings of 25600, or even up to something akin to 100,000! However, most people avoid these settings like the plague, and because they generally can't take images of a sufficient quality, are disabled by default.  If you want to turn them on, they may only be available if you enable "high ISO" settings somewhere in the deep menu settings of your camera.
      • By doubling your ISO number, you are making your recorded image appear twice as bright. Halving the ISO, halves the apparent brightness. Assuming you want your image to have the same apparent brightness, this increased ISO can be compensated for, by increasing your aperture's F-stop, (closing the iris) or increasing the shutter speed, or some combination of both. Of course, reversing these settings also holds true too!
    2. Aperture (also called "F-Stop"):
      • Inside lenses, there's an iris which performs a similar function to the iris in your eye. It basically makes sure that an appropriate level of light is let in so the sensor isn't overloaded, and focus is has some additional controls. Like opening up the curtains on your bedroom window, if you open it up, you'll make your room (or shot) brighter, close the iris, and you make the shot darker.
      • Firstly, a quick and easy way to remember how aperture values work. As I just said, lower F-Stop values = brighter image. Higher F-Stop values = darker image. If it helps, an iris' job is to BLOCK excess light, so a higher number blocks that light more and more. To go back to the window curtain analogy, the measurements relate to "how much curtain is covering the window", not the "how big is the hole?", which is why higher values render darker images.
      • What's with those weird decimal numbers?
        • So back in the early days of photography, lens makers clearly got organized at some point, and set the widest aperture at a standard ratio of aperture radius to the focal length of the lens and called it F1. If you halve the area of the iris' opening, this logically halves the amount of brightness in a shot (if all else is left equal). A little bit of maths tells us that in order to double the area of an iris' (which is almost a circle), you need to multiply the radius by the square root of 2 (roughly 1.4). To halve the area, you need to divide the radius by the same 1.4.  Remember, we control the iris, not the hole directly, so increasing the area of the iris, decreases the area of the opening. That's why higher values are darker. But the general gist is that the next number in the sequence is always 1.4x the previous stop radius and the exposure is half as bright as the previous setting. That sequence is:
        • F1, F1.4, F2, F2.8, F4, F5.6, F8, F11, F16, F22, F32 (that's the common range, but they do go further on each end for specialist lenses)
        • If each number is twice as bright as the next number, that means that F1 is 1024 times brighter than F32. However, some lenses may only go between F4 to F22 which means F4 is 32 times brighter than F22. That's still very usable.
        • Of course, you aren't limited to these whole-stop settings. Most cameras these days operate in either 1/2 or 1/3 stop increments for finer control.
        • You won't see many lenses at F1 or lower. They are frighteningly expensive. Arguably the most famous "fast" lens was an F 0.7 lens, made by Carl Zeiss for NASA, which Stanley Kubrick  bought and adapted to work on one of his films so he capture a scene lit only by candle light. Candles are generally NOT bright enough to do this, so that was cutting-edge back then.
      • Aperture and Focus, the side effects of changing Aperture:
        • The Depth of Field (DOF) refers to the range of distances from the camera that things will be in a reasonable degree of focus. Everything in front of that range (closer to the camera), or behind (further from the camera) will be blurred to some significant degree. Aperture is one of the main controls that affects your DOF. In short, if you open up the aperture (Low F-stop value, like 2.8), the less DOF you will have (think, blurred backgrounds). Similarly, if you turn the Aperture to F11, even F16, then you might have everything to the horizon in reasonable focus. However, once you start getting beyond F16, focus starts deteriorating for a different reason.. refraction caused by the aperture-controlling iris.
      • Putting it together with the other settings:
        • If you darken a shot by 2 aperture stops, (lets say you turned from F4 to F8) you could compensate for this by either increasing ISO 1 stop (say 100 to 200) and doubling the time that the shutter stays open (say 1/400th of a second to 1/200th of a second). This will increase your depth of field so things will look sharper, but backgrounds may be more distracting. Increasing the ISO to 200 should result in negligible or tolerable levels of noise on most cameras... (however that might change significantly if it was from 800 to 1600). Dropping the shutter speed may increase the subject's motion blur and/or your blur caused by "camera shake", but this would depend on the speed of movement, as well as the lens you're using. 1/200th of a second is likely to freeze most walking speed motion, but not particularly fast action... say spinning propellers on a plane or drone.
    3. Shutter Speed (How long the shutter is open for):
      • Shutter speed is perhaps the easiest to understand, and has the least amount of jargon about it. In short, the longer you leave the shutter open, the brighter your image will be. Conversely, the shorter the time the shutter is open, the darker the image will be. Cameras see light differently to us. Opening up a shutter, is like opening up a tap. Light (like water) will continuously flow into the camera and hit the sensor and fill it like a bucket until it overflows and just registers it all as "white". If the sensor isn't recording a video (which takes many still images a second), what's it to do with all that extra light? The answer: "It'll just register more light as "brighter".
      • Motion:
        • When a camera is open for very brief periods of time, it is darker, but motion is also more likely to appear "frozen", with motion blur being significantly reduced. Capturing a water drop in mid-fall is an example of a high-speed (short opening) shot. However, when you open the shutter up for longer periods of time, it gets brighter, but the odds of motion blur, and problems with "camera shake" become more likely. However, you can get impressive effects at the beach, where long exposures can make the waves look like a flat white bubbling sea. So motion blur is something that can easily be used to creative effect.
      • On most cameras. The shutter speed is measured by the length of time the shutter will be open. Say 1/500th of a second. Fractions are painful to make/read on cheaper electronic displays, so the shutter speed is indicated, not as a fraction but by the denominator by itself (which if 1/500th of a second is our example, would be shown simply by 500). Similarly, 1/5th of second would be shown on the camera simply as 5.
      • Now most people know fractions from school, but in the event that you have forgotten (or repressed) those memories. It's important to know that while 1/5 of a second is slower than say 1/400th a second. The 1/5 exposure is longer (80 times to be precise). Lower numbers = more time open. Larger numbers = less time open. But only when fractions of seconds are set.
      • But what happens when I want to go longer than a second?
        • The display shows the number of seconds followed by a single quote symbol (so 3" would mean 3 seconds). Much like the degrees, minutes, seconds notation used in angles.
          So, bigger numbers followed by a quote symbol relate to slower speeds, or longer opening times).
        • Most cameras will go up to 30 seconds (30") but to go beyond, you'll need to switch the camera to "bulb" mode which means "keep the exposure going for as long as I am pushing the button". I also recommend that you use a tripod, and consider getting a "cable release, cable remote, or wireless remote" to make sure you don't bump the camera when you're doing this. If you do a lot of long exposure shots, you might want to get a intervalometer which is just the same remote/release, but with programmable timers. Usually it will have setting like "delay until the shot is taken", "duration of each exposure", the "time between each exposure", and finally, "the number of shots you want to take in the sequence". Some cameras these days have Wi-Fi control, and you can do this from an app.
        • Remember, if you are running long exposures, the battery will be drained faster than you would normally expect. The sensor has to be continuously powered in order to continually record. Some exposures can run for hours, and then require the camera to process that for twice as long (known as "long exposure noise reduction")... so if you don't have multiple batteries, which are fully charged, you can run into failed captures... even more so when winter reduces your battery efficiency.
    This is my fourth attempt to do a long exposure. (Don't ask about the first three). I wanted to do this to capture the star trails caused by the rotation of the Earth. If a full circle is completed in a day, then you can actually use the angle caused by the arc of one of the star trails to figure out how long this exposure ran for.  The camera then ran an additional (and equal) period for the noise reduction process to complete. It can get pretty cold when you're standing on the top of a mountain in winter... in the dead of a clear night. To do this four times shows insanity.. or to put it more nicely... commitment.

    Putting it all together: Equivalent Exposure is NOT Going to Make the Image Look the Same!

    For example: You can increase all three settings by 1/3 of a stop and the overall image (since 3 x 1/3 stop  = 1 stop) will be twice as bright. That might be good to balance the negative side-effects of increasing the respective individual settings too much. Which would be great shooting inside a darkened room for a real estate shoot. Alternatively, you can maintain the recorded brightness (exposure) of the shot, but change the look of the image. For instance, you could increase ISO by two stops, (say 100 to 400) and even brighten it more by opening up the aperture by an additional stop, (F8 to F5.6). So now the image is three stops brighter, which is 2 to the power of 3 = 8 times brighter), so you can increase the shutter speed to 1/8th of the previous value (say 1/50th sec to 1/400th of a second) to freeze motion, or reduce blur caused by shaky hands. Great for moving targets like sporty people, flying birds, or running foxes!

    Seems like a good time to throw that cheat sheet in again, to save you from scrolling up!

     Going beyond the holy trinity of exposure. In other words, "What are all the other buttons, dials, menu options, and accessories for?"

    Most of the other buttons allow you to adjust things you probably don't need to adjust for every shot. Some of them include:

    • How colour is handled in camera, whether or not you're shooting in black and white, sepia or some other alternative.
    • The quality or resolution of your captured image files, whether you shoot raw, JPEG, full resolution, or some smaller file sized setting.
    • Some help to choose whether you use a single point to focus, or large areas of viewfinder.
    • Whether you prioritize the speed of focus over the accuracy of getting that focus lock (or vice versa)
    • Whether you shoot one image when you press the trigger, or in a repeated rapid fire (also known as "spray and pray")
    • Flash control, or perhaps remote control, GPS or WiFi access.
    • Maintenance functions like ultrasonically cleaning the sensor, formatting memory cards, allowing maintenance access to the sensor for manual cleaning.
    • Typical image processing, (sharpness, contrast, noise reduction, colour)

    Best advice to newbie photographers: Learn a little, and get off auto mode!

    Why Auto is not going to make you a pro photographer:

    Almost perversely, there's a lot of hype about cameras and their functions, and the technology they have hidden inside. It is all aimed at impressing people enough to buy one model or another. Don't buy into the hype too much, at the end of the day, you are the photographer. The camera, is merely a tool. Someone will always own better equipment than you. Just get over that! Owning the most awesome camera, and making the most awesome photos are often two very different things.

    Camera manufacturers claim many things, that their products are incredible with latest and greatest auto focused, sensor-detected, image-stabilized, colour-corrected, algorithm-assisted, and potentially satellite-linked, with near-instantaneous gratification monitor on the back. Ok, please remind me again, what is the photographer even there for?

    With all that hype going on, it's no wonder that cameras can be seen as near-magical devices designed by clever engineers to be easy to use.... and newbies confuse that with "Make taking National Geographic level photos as easy as gracing the camera with your presence. So ill-prepared newbies spend a fortune on fancy gear with lots of controls, and features designed to be used creatively... and then they choose to use Auto, which hands the reins back to the computer, and this is where too many people stop.

    These people don't know how to use their camera beyond Auto mode. I personally believe that they may lack confidence and don't yet feel as though they know what they're trying to say by taking a picture, or how to say it in the language of the camera. So let's look at how auto mode works, and why with the latest technology, auto seems to "fail" to take a great photo.

    Many of you might be using "Auto" mode to take your shots. It's convenient, you can recognize your friends in the photo, and focus works pretty well, but it just doesn't have that "pop" you see when a pro takes the shot. At least, not most of the time. Take enough photos, and you will get the occasional good one, just by chance. Alternatively, people starting out will take a shot on auto, then use post processing to "fix" it up later. Whether that's using Photoshop, or some alternative, this is actually a lot more work than getting it right "in camera", and needs a lot more expertise. But why spend your life processing photos in front of a computer when you can be out there enjoying all the world has to offer.

    So let's have a quick discussion about how auto mode works.

    Your digital camera has a computer in it. Inside, there's equipment designed to tell the computer how bright or dark the overall shot will be. This is called the "metering system". Like the story of Goldilocks and the Three Bears, auto knows that you don't want a shot that's "too bright" or "too dark", so it wants to take photos so everything has the brightness "just right". So it aims for something in the middle, and compensates when things go too far either way.

    Sounds great huh? Now you don't have to worry about the shots being all bright and dark... well that's only somewhat true....

    In Auto mode, the computer has complete control, and makes choices to get that brightness just right. However, it does not know what sort of photograph you're trying to take. There are many ways to come to a "middle brightness". The computer might decide if you are photographing a bright snowy scene, all that white means that it is overexposed, so it dulls everything to a boring grey. It might do this by closing the iris in the lens (upping the Aperture) it might increase the shutter speed, it may even drop your ISO, or some combination thereof. However, each of these adjustments have significant impacts on the overall look of the image. What's in focus, how motion is handled, even noise levels in the final image are also influenced by these changes, and you can't separate these side effects unless you know what you're doing.

    Alternatively, if you are shooting in a dark environment, the computer might decide that you need a flash, scare the penguins off and get you generally hated at the penguin sanctuary. Not to mention that the one photo you did get... sucks, and now all photographers are banned from visiting the sanctuary. Sigh. Be warned: This can happen in art galleries too. You can be "escorted" from the premises if you use a flash on famous works like a Rembrandt, or Picasso, as the light actually does degrade the paint.

    Remember that Auto always tries to help, but it can do so in really unhelpful ways. Now consider a conventional Christian wedding. The bride's in white, and the groom is in black. How do you think the camera will respond? Will it up the dark suit and blow out (over expose) the white dress, or will it down the wedding dress and render the groom as some sort of insidious shadow man. Frankly it's even money which way it'll go, unless you take control.

    Side note: Middle grey, which for most cameras falls somewhere around the 18% black, 82% white mix (also known as 18% grey). Yes, that's the middle... to most people's eye... and the camera too.

    Auto doesn't mean it'll carry itself, point it at something you'll find interesting, and take a shot. Sorry, we haven't gotten that far with the tech yet. The A.I. driven overlords will need to worshiped sometime in the future.

    Moral to the story:

    Learn a little, and get off Auto and take control!

    Let's move on to "composition".

     


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