pocket exposure guide
It's an essential part of photography : the fundamental understanding of light, and how we communicate that information to the camera in a way that gives us the results we want.
All too often, however, the basic framework surrounding the "exposure triangle" is made more difficult to understand by complex diagrams or huge chunks of badly-phrased wording, leading to confusion or information-overload for the reader.
When Paul was designing his photographic workshops, he started searching for a clear, concise, handy (and correct!) guide to give to attendees to ensure they'd have a reference or "baseline" for the key aspects of controlling exposure. The problem was, he couldn't find one anywhere.
There were many, many, "cheat sheets" or "guide books" out there, but they were either too crammed with unnecessary information, too difficult to read and understand, or (in some cases) just plain wrong. So, he set about creating his own guide that is given to every workshop student as a reminder for when they're shooting in the future.
Positive feedback from customers came back thick and fast: "I know someone else who'd like one of these" or "can I buy some for my friends?", were two of the more popular responses - so we've decided to make the guide available for anyone to purchase.
After all, knowledge is only really of value if it's shared, right? 😉
The guides are now available to purchase online through the print store - priced at only £3 each, plus postage, worldwide and include a plastic sleeve for safe-keeping.
Each card is matt laminated to ensure it's protected from dirt and small splashes (now you know it's been designed by a photographer, right? 😉 ) and comes in its flat format ready to fold along the machine-formed central join.
Being the same size as a standard credit card, these guides can be easily carried in wallets, camera bags or phone cases and holds all the key information relating to exposure values, including:
- ISO - sensitivity and noise levels explained
- Aperture - light and depth of field in detail
- Shutter Speed - exposure and motion by f-stop
- White Balance - changes in lighting situations
- The "Sunny 16" exposure rule in one simple chart
To order your copy, visit the online store now by clicking here! 🙂
using the exposure guide
We've gone for simplicity, but sometimes even the small things need a little explanation. With that in mind, here are the key points to remember when using the card as a reference:
A correct exposure is made of 3 key elements: Aperture, Shutter Speed and ISO, and generally expressed in "stops" or "f-stops".
> Aperture : "How big the hole is" - or how much light is physically allowed onto the sensor or film.
> Shutter : "How long the hole is open for" - or how long the light is allowed to continue exposing the sensor/film.
> ISO : "How sensitive is the film/sensor" - or how reactive it is to the light that it's given.
This scale provides you with the regular list of f-stops (where with each change you either halve or double the amount of light), along with shutter-speed stops (again, with each change where you're halving or doubling the amount of light allowed onto the sensor or film) and finally standard ISOs (with each change, doubling or halving the sensitivity). So, the general rule is, if you have a correct exposure (as shown) at f/4, 0.25 seconds at ISO 1600, for each column you move left or right, at least one of the other two must move in the opposite direction to remain correct.
For example: If your correct exposure is set as shown, but you want a faster shutter speed, to the left (maybe to 1/15th second, so "2 stops shorter"), you would have to move either your aperture to be 2-stops bigger (to f/2) or your ISO two selections to the right (ISO 6400). Of course, you can do a mix of both - maybe f/2.8 and ISO 3200, but the key rule to remember is that for each movement of one column left or right, one or both of the other two need to move in the opposite direction by that amount to maintain the same exposure.
Once the correct exposure is established, there are three "by-products" of those settings that we can then use to be creative with the final image.
> Depth of Field : From the nearest to furthest points, how much of the image is in focus.
> Motion : How much motion or movement is captured during the exposure
> Noise : How much grain/noise is present in the image, the more sensitive, the more noise.
As with exposure, this scale provides you with the regular list of f-stops but also the likely effect achieved as a result of moving up or down the exposure scale. Longer shutter speeds mean capturing more movement/motion (and camera shake). Wider apertures mean narrower depths of field. Higher ISOs, while allowing to shoot in low light or with extremely fast shutter speeds also result in more noise or unwanted "dots" in the final image. Much like the exposure scale, these image properties are intrinsically linked: move one to the left, another (or more) must move to the right in order to achieve the same exposure.
For example: If you're set on the example as shown, and definitely want a 1/4 second exposure, but you're not happy with the amount of noise in the final image, in order to reduce that (shift the noise level to the left), you must then compensate by opening your aperture wider, with a lower number. That has the effect of also decreasing your depth of field (which this side of the card will remind you), but will result in the same exposure with less noise.
white balance / colour temperature
Despite being something we see every day, it's easy to forget that white light actually comes in the form of very different "temperatures" - from warm yellow glows to cold blue shades - and our brains are compensating for this all the time.
"White balance" or "colour temperature" simply refers to how "warm" (orange, to our eyes), or "cold" (blue, to our eyes) the perceived white light actually is in reality. If you hold a piece of white paper up at sunset, you'll see it glow in golden yellow light, but that same piece of paper in a storm or against the light hitting a snow-capped mountain will look very different - a blue tint that appears colder to the eye. All sources of light have a "colour temperature" which is measured in degrees Kelvin, and modern cameras can also compensate for this change across different situations.
In this scale, we've detailed some of the more common colour temperatures for various situations. While many are happy to leave their camera on "auto white balance" mode, over time, people generally want to start exercising more control over what the camera is actually recording.
While not absolute, plugging these reference numbers into your camera when shooting can force an accurate rendition of the scene with the correct lighting temperature as you are experiencing with your eyes. Alternatively, knowing how to manipulate white balance can also allow you to completely alter the feel of a scene from warm and soft to cold and harsh, in part down to this one setting.
the "sunny 16 rule"
This is the simplest way we could display one of the most intricate, yet fundamental, guidelines for standard photography - and hopefully we've managed to make it easy to understand.
The "sunny 16 rule" refers to the fact that if you shoot on a sunny day, at f/16, your shutter speed should be a reciprocal of your ISO (so, in other words, ISO 100 = 1/100th second) - and that will result in a broadly correct exposure.
The problem comes with the definition of "sunny day": not all days are actually sunny (so what do you do then?), and how do you define what is "sunny enough" to make the cut?
In this part of the guide, we've pulled together all aspects of lighting conditions into one chart, and using your knowledge from the "exposure" and "image properties" pages above, you can then easily interpret what settings you need to achieve the outcome you're expecting.
In this example, it's cloudy outside. If you wanted to shoot according to the "sunny 16 rules" with an ISO of 200, you would use those settings displayed : f/8 for 1/200th of a second. But what if you wanted more of the scene in focus (increased Depth of Field) by reducing the aperture down to f/16? Well, for each "stop" down you move the aperture value, just as before, you'll need to increase either the shutter speed by 2-stops the other way (in this case to 1/50th second) or the ISO by two stops (ISO 800) - or, as before, a mix of both.
Hopefully that all makes sense. As you'll see, we've crammed a lot of theory into a credit-card-sized guide, but with the explanations above, you'll find these cards as invaluable as our workshop students do every day!
To order your copy, visit the online store now by clicking here.