A Game Of Light - Capturing Your Story (Part 3)


Alright! Here’s where we really dig into the exposure triangle!

Last time I introduced the three points of the exposure triangle:

• Aperture

• Shutter speed


One day, I was with one of my friends who had received a digital camera from her dad years before. But, she hadn’t really bonded withit. She said she didn’t really understand manual mode, so she tossed it into the abyss of the forgotten. That day, she asked me about taking a photo with a blurry background. I’m going to explain how you would control that.

But first, let’s talk numbers. Setting the parameters of the exposure triangle to get a blurry background involve numbers and a little bit of math. It’s not difficult math. It’s mostly simple multiplication and division-and sometimes just memorizing. I promise, you will get it.

Let’s start with ISO.


ISO is probably the easiest to explain to me, so I’ll start there. If you remember from my earlier post, ISO deals with how sensitive the camera’s sensor is to light. The more sensitive it is, the more light it is able to collect.

As sensitivity increases, ISO usually increases by doubles. The more sensitive, the more grain or noise that is created. For some, that’s a nice effect. For others, the smoother the photo the better.

Most cameras start off with an ISO of 100. So the typical sequence for ISO settings would be: 100, 200, 400, 800, 1600, 3200, 6400, and so on and so forth. Newer cameras go even higher. Notice that starting from 100, to get to the next setting you only have to multiply by two. So, to go back down from a higher setting, you divide by 2. See? Simple, right?

So, with ISO, each time you go up you, say from 100 to 200, you are doing what photographers call increasing “a stop” of light. At ISO 200, you are making your camera have double the amount of light sensitivity than it had at 100. Conversely, when you go down from 200 to 100, you are cutting the amount of light sensitivity in half.

Not so difficult to understand after all, right? :) Lets move on to shutter speed.

Shutter speed

Shutter speed can be used to great creative effect because it is the part of the triangle that deals most with motion. When you want to take a photo of your child sliding into home base, you may not want it to be frozen in place. You may want to see the effort, the struggle, the speed! So, you will adjust the shutter speed to get that motion. On the other hand, if you want to catch the shot where she caught the ball to strike out the last batter, you might want that frozen. Setting your shutter speed will help you accomplish this.

The typical sequence for shutter speed is, 15, 30, 60, 125, 250, 500, 1000, 2000, 4000, and so on. These numbers are actually fractions. So, 60 is really 1/60 and it means one-sixtieth of a second. That’s how long your shutter is allowing light to hit your sensor. Even though 1/125 of a second has got to be pretty fast, 1/4000th of a second in photography terms is so, so much faster.

Like the ISO setting, going up or down the sequence for shutter, means doubling or dividing light in half by a stop (depending on how many stops you’re going, of course). If I need another stop of light at 250, to get it using the shutter speed, I will need to allow light in another stop by cutting the rate at which the shutter curtains close by half. So I change my setting to 125.

But, keep in mind that as a subject is moving in space, the longer the shutter speed is open, the more motion you will record, whether it is the subject, or at times, your own hands (the latter is called camera shake). If you checked out my last post, you’ll see the photo of a fish my daughter caught where the fish was in motion. I wanted to show that blur of motion as the fiesty, little guy wriggled to get off the hook. (No worries, he’s free today. It’s a catch and release park. :) )


Now, while the whole exposure triangle is super-important, aperture is probably one of the main ways photographers make their photos stand out. It’s a large part of what creates those blurry backgrounds my friend was interested in that day.

In fact, what she was referring to is called depth of field. I know, I know…another term. But, without getting into too many particulars, depth of field has a lot to do with blurry backgrounds or backgrounds that are sharp and have a high amount of detail. When the depth of field is shallow, the background is blurry. The shallower the depth of field, the blurrier the background will be. Depending on your camera’s lens capabilities, it can be really shallow when your aperture is set wide; Or it can be really deep, when your aperture is set really small.

Depth of field also relies on how close or far your subject is to its background as well as the focal length of your lens. But, suffice it to say that, of the three parts of the exposure triangle, the aperture is the one that most contributes to this blurry phenomena. Again, in my former post, you can see in one photo where our favorite guy’s hands are very close to the camera and his feet are far away to emphasize a particular part of the fishing process.

The aperture has it’s own set of numbers too. A typical sequence for the aperture is: 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, etc. Those numbers can seem a little wonkier (and not all camera lenses have the whole range…some may start at 4 and others may go up to 32, etc.). But, if you notice, there is still a pattern with this sequence. Starting from the 1, every other number doubles….and starting from the 1.4, every other number doubles (pretty much).

Also, just like with ISO and shutter speed, there is this whole deal with doubling the light by going up a stop and chopping the light in half when you go down a stop. However, with the aperture, it’s a little trickier to keep straight since we know numerically 16 is greater than 1, but in photography terms, at 1, the aperture is at it’s widest and allowing in a lot of light, while at a larger number like 16, it’s a lot smaller and allowing in very little light by comparison. It’s backwards sounding, I know. But, let’s say my lens’ maximum aperture is at 1.4. If I want to decrease my light by a stop, I’d have to change my setting to 2. That would be considered cutting my light by a full stop.

Why Background Blur Anyway?

Back to those blurry backgrounds…When it’s at its widest, the camera lens has it’s shallowest depth of field and the background will not be as sharp as when the camera lens is at its smallest aperture. Adjusting this setting allows you to control just how much background blur (or not) you want to have in your photo. Honestly, you may not always want all of the background to melt into nothingness. It all defends on why you’re introducing the blur in the first place.

One of the best ways that this background blur is used by photographers is to eliminate clutter and to define a subject to isolate it from its background. If you take a look at the intro shot, you’ll see how the photo has a bunch of greenery in the background. But it’s pretty articulated in that shot. It’s distracting for someone like me. But, if I adjust my aperture just a bit, I can “clean it up” so to speak.


Let’s say you want to take a photo of a detail of your child’s birthday party. Maybe it’s the candle on the cake or a birthday favor. For now, you make that the subject of the photo, so you want that in focus. So you open your camera’s aperture wide open to 1.4. But, when you take the photo, all you see is the birthday hat and a ton of bokeh balls (those pretty circles of light created when you have a shallow background) and you feel like you didn’t just want a portrait of the birthday favor. The real subject for you is now the liveliness of the birthday party it represents. Now, you want some context too. You think, “Wouldn’t it be nice to see a little bit of the presents on the table and the kids running around the back in their cute, little outfits?” In that case, you would need to adjust your aperture setting so that the background isn’t totally blurred out. You may need to “close down” your aperture to 2 or even 2.8. That will allow you to get a little more of that background in focus.


A Conundrum

Now that you’ve closed down, you’ve lost some light you needed for that shot. You’ve cut it in half-twice! You’re getting a quarter of the amount of light you originally had-and that light was nice! How do you get that light back?

Exactly. Your triangle will have to compensate for the loss of light somehow. How do you think it does that?

Photography is a game of light. If you can remember the definition, that itself will take you far. But, once you have acceptable settings for light, if then you manipulate a point on the triangle to tell the story more artfully, you will inevitably allow in more or detract light. Once you do that, one of the other points on the triangle needs to be adjusted in order to compensate in a way that does not detract from your story.

And therein lies the rub...If I use my ISO, my photo may get grainier or noisier looking. If I use the shutter speed, I have to think about the amount of motion I’m recording (and if I want that) or if I will need a tripod so as not to record the movement from my own hands.

In essence, the exposure triangle is often a set of trade-offs to get you to a desired result. But, we’ll talk about that one next time.

My friend practiced using this new information on the size of her aperture to isolate doorknobs that day from their backgrounds in her house. But, she has no toddlers lol. You should take this knowledge and go practice on that crumbsnatcher of yours. Pick up that camera you wrote off and capture a beautiful story of your family today. :)