Photography: This Triangle Thing, AKA Exposure Triangle.

This post was inspired by some comments about photography in other articles.  I hope this is helpful and clears up a whole range of things about DSLR cameras.

Copious amounts of websites talk about photography and at the same time, bombard people with phrases that do not mean a great deal, and if new to photography, quite pointless because who would know what to search for anyway.  With that said, what we are going to focus on here is balancing our brightness while taking a photo.  For example dark, bright, blurry and all those things that raise the question ‘why?’.

Before we get into the tech bits, let us consider the camera.  Aside from the millions of functions they have, they all so the same thing.  A little shutter opens, lets in some light and closes again.  That is the core part of any camera.  Now let us consider a bath full of water that is over full.  We pull the plug out, water goes, plug back in.  How much water did I let out?  well, that depends on how big the plug hole is and how long I had the plug out for.  Remember this analogy as we talk about shutter speed and aperture.

What is exposure?  How light or dark a photo is.  Not complicated so we will look at what makes photos light or dark.

Shutter speed: You press the take picture button on your camera, the little shutter opens for a tiny amount of time then closes.  Like a plug in a bath.

Aperture size: The is the size of the hole in the lens that lets light in.  Like a plug hole.

ISO-level:  How sensitive the camera is to light.  Kind of like something sucking the water down a pipe rather than it just flowing down the hole.

We can see we have three things that work together to let right the right amount of light into a camera for the right amount of time.

The Analogy

We have our bath, it is full and warm with bubbles.  Imagine we wanted to let out exactly 5 litres of water, how would we do that? Well, I am not a physicist but I think I would start with how big the plug hole is and how long do I need the plug out for.  I might end up with a number that would mean how long the plug would need to be pulled out for.  Too long and too much water goes and too little amount of time and not enough water would leave the bath.

Analogy to Camera

Our plug is the aperture.  If we have a huge aperture (F4 or F5), then lots of light will flood in.

The shutter is represented by the amount of time the plug is out, so if the shutter is open for a long time, again lots of light.

Lastly, the ISO.  This would be a pump sucking the water out.  A high ISO, say above 400 will be very sensitive to light.

How does this affect the photos?

Too much light flooding in will make your photo very bright, overexposed.  Not enough light, caused by a tiny aperture (F22) and a fast shutter (1/2000) will give you a very dark photo, underexposed. We have to balance this.

A little under exposed can add to the mood.

A little under exposed can add to the mood.

What can we do to avoid over/underexposed photos?

We balance the Aperture/Shutter speed.  Normally the ISO would be set quite low (100 or 200) to avoid grain in the photos.

If we are doing landscape and we require a small aperture (F16), and slow down the shutter speed.

Nicely Balanced Exposure

Nicely Balanced Exposure, slow shutter with a small aperture. (F11)

If we are photographing a moving pet and require a fast shutter speed, alter the aperture (Maybe F4).

Fast shutter speed with a high iso catching this dog frozen in time

Fast shutter speed with a high iso catching this dog frozen in time



Most modern DSL’s like Canon, Nikon, and Sony have settings for Aperture priority and Shutter priority.  This means we only need to focus on the one thing left out.  ie, in aperture priority we can focus on the shutter speed and the camera can take of everything else for us.

The viewfinder will more than likely have an exposure reading.  This is the main thing to watch as you press the shutter.  It should be on 0, if not, alter the setting you need.

TIP:  Don’t bother trying to hold a camera if the shutter speed is below 1/200.  The photo might look ok in the viewfinder, but unless you have super steady hands, it will be blurred.

Note:  The idea is not to get onto the manual setting on a camera, the goal is to understand your camera.  All the various modes on a typical DSLR have their uses but, as long as you get the photo you want, it does not matter what setting your in.

Strive to get the picture you want, not the dial setting.

So, if you take a picture and it looks super bright, chances are that too much light is flooding in and similarly if the photo is dark, not enough light.

Too much light: Increase shutter speed, narrow aperture, above F11. (Such as  f/16, f/22)

Not enough light: Decrease shutter speed and widen the aperture. Under F11. (Such as F4, F5.6, F8)

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