In this post, we’re talking about how to use the exposure triangle when making photographs: reading the light, setting your ISO, choosing your aperture, and finding the right shutter speed.
On any given Sunday morning, you can (hopefully) find me lost in the wilderness. It’s a big part of why Loop doesn’t open until midday. As an early riser, I’m often up at 6am anyway, so I figure I may as well head down to our local creeks. On this particular day, after a conversation with a good friend and long-time Loop supporter, Leah, I found myself strolling alongside Sassafras Creek.
From the moment I start walking, I'm paying close attention to the light.
Start With the Light
In photography, light is everything. So take notice of what’s there. Is the sun out, or is it cloudy? Is it morning, midday, or afternoon? Each of these variations changes your photograph. It’s why so many landscape photographers head out at the very beginning or the very end of the day, when the light does something particular to colour, and to the way it falls across a scene.
I’ve mentioned this here before, but there’s a little game I like to play when I set out on a photo walk: I try to figure out what settings the camera is going to need before I’ve even framed a shot. I have a favourite ISO I use almost every time, and with that as my starting point, I work out what the aperture and shutter speed need to be.
Setting Your ISO
ISO dictates how sensitive your sensor is to light. The higher the number, the more sensitive it becomes. We covered this in more detail in a recent post, worth a look if you want the full picture. For a morning like this one, I set ISO first, and I keep it as low as possible to hold onto the most dynamic range.
Choosing Your Aperture
From there, I want to know how much of the scene will be in focus, from foreground to background, and that’s when I set my aperture. What I’m really asking myself is: how deep into the photograph do I want the viewer to be able to see? Do I want them to notice detail all the way to the back of the frame? Or do I want their eye to land on one single thing?
For most of my own photographs, it’s the latter. I love a shallow depth of field. At a low aperture like f/2.0, very little is in focus, an effect I explored in an earlier post about sensor size on a full-frame camera. A low aperture will also darken the edges slightly, adding a soft, natural vignette.
Finding the Right Shutter Speed
And that, in turn, helps decide what your shutter speed needs to be.
On this particular morning at the creek, I was torn. I loved the shallow depth of field a low aperture gave me, but I also wanted the water to look dreamy, almost ghostly. To get that effect, you need a slow shutter speed.
If you head to our Instagram page, you’ll find our pinned posts on the exposure triangle. In the one on shutter speed, I talk about how anything moving through the scene while the shutter stays open will appear as a soft blur in the final photograph. That’s exactly how you get that dreamlike, silky water look in a creek, river, or waterfall.
So here, you’ll see two photographs from the same spot: one with a shallow depth of field but crisp, sharp water, and another with a much deeper depth of field that also carries that soft, dreamlike water look. I also used a couple of filters on my lens that morning, which helped bring out the effect you can see here.
Come Learn It With Us
If any of this sparked something, if you’ve stood at the edge of a creek with your camera and wondered how to get that shot, we’d love to have you along. We’ve just opened a handful of spots for a photography workshop right here on Sassafras Creek.
We’ll walk through everything you need to make photographs like these: filters, camera settings, tripod technique, all of it, in the same light, on the same water, with plenty of time to ask questions and try it yourself.
Loop members get half price.
FAQ: The Exposure Triangle
What is the exposure triangle in photography?
The exposure triangle is the relationship between ISO, aperture, and shutter speed, the three settings that together control how much light reaches your camera’s sensor and how a photograph looks.
How do I use the exposure triangle for landscape photography?
Start by reading the light in the scene, then set your ISO as low as possible for maximum dynamic range, choose an aperture based on how much depth of field you want, and adjust your shutter speed to control how motion (like moving water) appears in the frame.
What aperture is best for a dreamy water effect?
A slower shutter speed, rather than aperture, creates that soft, dreamlike look in moving water. Aperture instead controls how much of the scene stays sharp from foreground to background.