HOME | DD

nadjasybill — The Exposure Triangle Tutorial
Published: 2013-09-04 03:40:32 +0000 UTC; Views: 4646; Favourites: 100; Downloads: 0
Redirect to original
Description body div#devskin0 hr { }



Aim
So, you've got your spiffy new DSLR because you wanted to take your hobby to the next level. You've gone trigger happy and annoyed all your friends with that constant clicking noise and blinding light. You've taken some pretty decent shots in Auto Mode, but they don't always turn out the way you want them too. Your photos are sometimes too bright, too dark, blurry or (unintentionally) grainy.

This tutorial aims to help you to explore your camera's Manual Mode in order to improve the quality of your work and to give you much more control over the outcome.


The Exposure Triangle
The Exposure Triangle consists of three main points: ISO, Aperture and Shutter Speed. Understanding these three things is key to becoming a better photographer and getting the result you want. In my next tutorial, I will explain how these three elements influence exposure and how they can be altered to create an evenly exposed image. For this tutorial, I will just focus on these three points to help you understand how they work. I will start with my favourite: Aperture.


Aperture
This refers to the opening in your lens that lets light in. The aperture size can be adjusted to let more light or less light in. When the aperture is adjusted, the depth of field changes with it. If you are not familiar, depth of field is the range of distance that appears focused or sharp in the photo. A large depth of field means that much of the photo is in focus (for example, what you would see in landscape photography), whereas a small or shallow depth of field means that only a specific subject or part of that subject is in focus (for example focusing on a single petal of a flower with the rest of the image blurred).

Have a look at these two photos:

The image on the left was taken with an aperture of f/2.2. You will notice that only the staples in the front and part of the carpet are fully in focus. The rest or the photo is strongly blurred. The image on the right was taken with an aperture of f/20. Almost everything in the photo is in focus -- except the very back. You may ask, "what is this funny figure with the 'f'?" It's called an f-stop and is used to tell you how wide your aperture is set at that moment.

Now, here's some frustrating logic: the smaller the f-stop number, the larger or wider the aperture (or lens opening). In the example above, the photo taken with f/2.2 has a large or wide aperture, whereas the f/20 photo has a small or narrow aperture. A good way to make sense of this is to not see the f-stop numbers as whole or compound numbers, but as fractions.

For example, 1/2 of a pie is much larger than 1/8 of a pie and certainly larger than 1/22 of a pie. Get it?



Here is what my old soviet lens looks like when the aperture is adjusted
(click to see the animation)

To recap:
The larger the aperture, the more light gets in through the lens.

The larger the aperture, the smaller the f-stop number.

The larger the aperture, the blurrier the background.

And vice versa.


If you are interested in knowing more about the technical aspects of f-stops, then have a look at this Tedious Explanation of the f/stop .


Shutter Speed
The shutter speed refers to the length of time the shutter is left open and is measured in seconds. On your camera, you will see numbers like 1/20 or 1/125 which mean a 20th of a second or 125th of a second respectively. The longer your shutter stays open, the more light gets in.

However, leaving your shutter open longer also means that the chances of motion blur are much higher. The shutter speed is basically how long your camera takes to capture an image. If you have a moving subject and a long exposure (shutter open longer), your camera will record the movement from the moment you press the shutter release button to the time you set it to close.


Using different shutter speeds while dropping a ball of paper

In the example above, you will see that the motion blur becomes less and less until you get to the last image on the right where there is no blur at all. You will also notice that the photo keeps getting darker and darker -- this is because faster shutter speeds allow less light than slower ones. Faster shutter speeds help you to catch subjects in movement with sharper detail. It gives that lovely frozen in motion effect.

Why would you want a slow shutter speed? Sometimes motion blur is desired -- for example when capturing fireworks, you want to see the trail of light from beginning to end. Motion blur can also make an image surreal or more dramatic.

So what do you do if you don't want the blur? Are your shots sometimes unintentionally blurry? It happens to the best of us. In auto mode, your camera will often select a slower shutter speed to compensate for low light. This will cause your photos to look blurry from camera shake. Aside from using flash, there is another way to solve this problem.

There is a rule of thumb:

The shutter speed should be the same or larger than the inverse of the focal length.

For example, if you have a lens with a focal length of 50mm, then the shutter speed should be 1/50 or less (less meaning quicker). Some argue that it is better to use the formula: 1/2xFL, so if you have a focal length of 50mm, you should use a shutter speed of 1/100 for a really sharp image. Here is an article where you can learn a bit more about lenses: www.cambridgeincolour.com/tuto…

Another way to avoid the blur is to keep your shutter speed high but open up your aperture to let in more light. However, opening up the aperture reduces the depth of field, which may not always be desired. This is where knowledge of ISO comes in handy. Before I continue with ISO, here's a quick

Recap
The slower the shutter speed, the more light is let in.

The slower the shutter speed, the higher the chances of motion blur.

Faster shutter speeds are great for photographing subjects in motion, for example athletes in a game.

Rule of thumb for avoiding blur due to camera shake (if you don't have a tripod): The shutter speed should be the same or larger than the inverse of the focal length.


ISO
The ISO measures the sensitivity of your camera's digital image sensor to light. The higher the ISO, the more light it picks up and vice versa. Low ISO means smooth images with very little noise/grain. High ISO means that the image appears brighter, but it also becomes grainier. Higher ISO comes in handy in low-light situations where you would need a faster shutter speed to capture the moment.


Comparison of shots in a poorly lit room with different ISO settings


In the first image, you can see a bit of motion blur in the fingers because of the low shutter speed. To get the image sharper, I bumped up the ISO and increased the shutter speed. You will notice that each image gets sharper. There is also more grain in the sharper images. The darker the room, the more grain you will see if you up your ISO. Here is a guide for further reading: digital-photography-school.com…

Recap
The higher the ISO settings, the more sensitive the sensor gets to light, which means sharper shooting in low-light conditions.

The higher the ISO settings, the grainier or noisier the image appears.

Very low ISO settings make an image appear very smooth, but this works better when sufficient light is available.


Conclusion
So, this is the end of my Exposure Triangle tutorial. I hope that it was useful to you in some way. I am no expert in photography, but learning these aspects of photography have helped me immensely in my quest to become a better photographer.


Did you enjoy this tutorial? Was it helpful? Your feedback would be much appreciated as I intend to write more of these. Thank you

Next up: Understanding Your Exposure Meter

References
Exposure triangle: www.kruger-2-kalahari.com/expo…
Exposure triangle DP School: digital-photography-school.com…
The Easy Guide To Understanding Aperture: www.redbubble.com/people/peter…
Focal Length Rule of Thumb: gizmodo.com/5940329/shooting-c… photo.stackexchange.com/questi…
How to Shoot in Manual Mode -- the Basics: clickitupanotch.com/2010/09/sh…
And me own experience

My Other Tutorials
Understanding Your Exposure Meter
Why I Now Always Shoot in Raw

Related content
Comments: 21

AfricanObserver [2015-10-03 09:16:16 +0000 UTC]

Duly added to my collection - exactly how I see it, and you have illustrated it well. A generous act!

👍: 0 ⏩: 1

nadjasybill In reply to AfricanObserver [2016-03-07 22:19:20 +0000 UTC]

I'm glad to hear that it was useful!

👍: 0 ⏩: 0

miontre [2013-12-19 07:07:15 +0000 UTC]

Thank you, this is really useful

👍: 0 ⏩: 0

etienne242 [2013-09-13 14:07:51 +0000 UTC]

Well done

👍: 0 ⏩: 1

nadjasybill In reply to etienne242 [2013-10-25 17:07:20 +0000 UTC]

Thanks!

👍: 0 ⏩: 0

tatankanuk [2013-09-08 01:45:43 +0000 UTC]

very good explanation!

👍: 0 ⏩: 1

nadjasybill In reply to tatankanuk [2013-09-09 04:01:21 +0000 UTC]

I'm happy to hear that! Thanks!

👍: 0 ⏩: 0

UnknownSingularity [2013-09-06 05:05:06 +0000 UTC]

I suck at taking pictures, despite having a good camera, I always wondered what were all those funny controls for


Now, I should try something and play with them

👍: 0 ⏩: 1

nadjasybill In reply to UnknownSingularity [2013-09-07 15:57:52 +0000 UTC]

I'm glad this helped! And I'm sure they don't suck

👍: 0 ⏩: 0

Nx3Fox [2013-09-04 17:35:44 +0000 UTC]

Knew all this already but this is still a well made and useful tutorial.
Thanks for sharing and good work

👍: 0 ⏩: 1

nadjasybill In reply to Nx3Fox [2013-09-07 15:57:00 +0000 UTC]

Thank you very much for your kind feedback!

👍: 0 ⏩: 0

Seki9 [2013-09-04 17:28:44 +0000 UTC]

Great tutorial. Simple and easy to understand. Although I already know all this stuff I'm surely going to recommend this to any beginning photographer.

👍: 0 ⏩: 1

nadjasybill In reply to Seki9 [2013-09-07 15:56:43 +0000 UTC]

Thank you! I found that when I started photography I couldn't make much sense out of this, so I tried to explain it in a simpler way. I'm glad to hear that it was easy to understand!

👍: 0 ⏩: 0

nightshade18 [2013-09-04 16:54:26 +0000 UTC]

Man! I wish I had this explanation when I was taking stupid photography during my first semester in college it would have made my life so much easier than just saying it to me in just words.

👍: 0 ⏩: 1

nadjasybill In reply to nightshade18 [2013-09-07 15:55:43 +0000 UTC]

Hope it's still useful to you now

👍: 0 ⏩: 1

nightshade18 In reply to nadjasybill [2013-09-09 02:49:14 +0000 UTC]

Lol! Thank god no that teacher made me hate photography afterwords so I'm good not like it's going to be of any use in my field I'm in now any way.

👍: 0 ⏩: 1

nadjasybill In reply to nightshade18 [2013-09-09 04:01:50 +0000 UTC]

That's unfortunate.

👍: 0 ⏩: 0

anilbujji [2013-09-04 11:32:54 +0000 UTC]

Excellent

👍: 0 ⏩: 1

nadjasybill In reply to anilbujji [2013-09-07 15:55:24 +0000 UTC]

Thank you!

👍: 0 ⏩: 0

Tamerathon [2013-09-04 04:58:20 +0000 UTC]

This is an amazing tutorial, and dead on.  I'd like to add a few points:

1)  Because of the triangle, some shots are, simply put, impossible.  They will be beyond the technical capabilities of your camera.  Each aspect of the triangle is a trade off.  If you want a fast shutter speed with a high f-stop, then you will have to compromise on ISO and noise.  Low noise?  Gotta have a low ISO.  A tripod, and a stationary subject can alleviate some of these problems.  So can a flash, which brings me to my next point.

2) The shutter on your typical DSLR consists of two curtains.  The first curtain opens, exposing the sensor.  Then the second curtain closes, covering the sensor.  At low shutter speeds, the sensor is fully exposed.  At faster shutter speeds though, the first curtain is still uncovering the sensor when the second curtain starts to close.  The maximum speed that the camera can manage and fully expose the sensor is the flash sync speed.  Fire a flash at speeds higher than sync, and you'll actually see the curtain on your image as a black bar.   Flash sync speed greatly limits some of your work when you use a flash, as most cameras won't go over it.    Cameras with high speed synchronizing options can psuedosync their flashes to higher shutter speeds.   They do this by extending the duration of the flash.  Instead of a flash being 1/10,000 of a second, it may be 1/250th of a second, so that the flash is active during the entire exposure of the sensor.    This is a large drain on the batteries of your flash though.  

That's all I can think to add for now. 

👍: 0 ⏩: 1

nadjasybill In reply to Tamerathon [2013-09-07 15:55:11 +0000 UTC]

Thanks so much for this again!

👍: 0 ⏩: 0