There’s something wrong with me. I can’t say the word ‘exposure’ without my mind adding a few ‘tee hee hee’s. I mean, how old am I?
Now, quite apart from my immature giggling, the exposure we’re currently learning about is the way light meets and greets our camera. If you get the basics right, the two should get along famously. A half-press on your camera’s shutter button (some are set to have a little ‘dingalinga’ sort of noise when you half press them – helpful for us beginners, annoying for everyone else) will allow your camera to take a light reading of the scene you are looking at. Your camera’s viewfinder will then show the values and settings activated by the current light in the scene on the light metre. This is basically shown on the metre from -3 to +3. You adjust from there, using the three contributing elements of exposure. You’re going to get to know these three elemnts so well that you’ll be besties in no time.
How much light do I have to work with?
ISO measures the sensitivity of the image sensor. So, when you are shooting in low light situations, you will generally increase your ISO setting in order to get a faster shutter speed. The cost of a higher ISO setting is grainier shots – there’s a lot of extra ‘noise’ being captured in the shot as well as what we’re after. This is sometimes worth the cost because you can capture images in lower light without needing a flash or other artificial light source. Grainy shots can sometimes be artistically lovely (just think of all those Instagram filters), but the general rule of thumb is to use the lowest ISO level possible… so shooting where there is lots of available light is good for us beginners.
When shooting outdoors during the day, an ISO of 100, 200 or 400 will be suitable. By selecting a higher ISO level, you would be taking photos in a dark or overcast setting.
Is my subject moving and do I want to freeze it?
Shutter speed is the amount of time that the shutter is open and therefore the amount of light that is let into your image sensor.
Shutter speed allows you to vary the way you capture a moving image. Consider that the options here are endless – are you shooting a footy game and want to bring the player holding the ball into focus but blur the rest of the team? Or do you want the whole team to be in the shot? Now, are the team playing at the time, or standing still in that standard ‘I’m a footy player with my arms crossed, look at my biceps’ pose they do? All of these variables will mean you’ll need a different shutter speed to accurately capture the shot the way you are framing it in your mind.
My favourite kinds of shots that manipulate shutter speed beautifully are shots that capture running water.
How much of the scene do I want to have in focus?
The aperture controls how open the lens is when you are shooting. The more open the lens, the greater the amount of light in your shots.
Aperture is measured in ‘f stops’. One stop halves or doubles the amount of light entering the lens. The confusing bit is that larger apertures (lots of light) have smaller f/stop numbers and smaller apertures (little light) have larger f/stop numbers. So f/4 is a larger aperture than f/22. Actually, that’s not the only confusing bit now that I’ve read through this post so far… but I just know that with some practice, we’ll get the hang of it.
The other thing to keep in mind is that it is generally your aperture that controls your depth of field. A higher f-stop number (lower aperture) generally creates a shot that has most of the image in focus (deep depth of field). A smaller f-stop number (higher aperture) focuses on one element and blurs the rest of the shot (shallow depth of field). Your eye works with both a large and small aperture, allowing you to see both large and shallow depth of field depending on where your focus is. Consider this when you are setting up your shot – what ‘looks’ best to the naked eye and how can you reproduce this in your shot?
Getting our three friends together
Arriving at the ‘correct’ exposure is a juggling act between the three pals we’ve just met – ISO, shutter speed and aperture. How much of each component do you need to get the effect you want in your shot? Increasing one will generally mean increasing the others, unless you are deliberately creating mood through over or under exposing your shot. The only way to really get to know the relationship between this dynamic trio is to take lots and lots and lots of shots, adjusting each element as you and analyse the outcome.
You can also download this handy A4 cheat sheet I made to get you started. Click on the image, right click and save to your computer and print.
Now, go out and take a million shots for practice and have fun!