# How aperture is measured

## Video: How aperture is measured

Shutter speed is a fairly easy thing to understand, because we are all familiar with fractions of time. Minutes are fractions of an hour, seconds are fractions of minutes, the line at the DMV is a fraction of your life you will never get back, and so on. Aperture is a little more complicated. You have seen how the iris in your lens closes down to block out more light. What makes aperture a little less easy to understand than shutter speed is that when it comes times to specify the size of the aperture's opening, we are talking about measuring the area of the circle, and that's something most of us don't have much experience with.

## How aperture is measured

Shutter speed is a fairly easy thing to understand, because we are all familiar with fractions of time. Minutes are fractions of an hour, seconds are fractions of minutes, the line at the DMV is a fraction of your life you will never get back, and so on. Aperture is a little more complicated. You have seen how the iris in your lens closes down to block out more light. What makes aperture a little less easy to understand than shutter speed is that when it comes times to specify the size of the aperture's opening, we are talking about measuring the area of the circle, and that's something most of us don't have much experience with.

Over time, you will simply memorize what we are about to see here. Aperture sizes are denoted with an f- s top number, and the bigger the number, the smaller the aperture. What we are seeing here is a list of standard aperture sizes, ranging from a fairly wide f/2.8 to a fairly small f/16. What you can't tell from looking at the numbers, or at the size of the openings for that matter, is that these apertures are each one stop apart--that is, each smaller aperture lets in half as much light as the previous aperture.

Now, here is the depth of field bit: wider apertures yield shallower depth of field. So in this chart, the wide open f/2.8 aperture, will have very shallow depth of field, while the narrow f/16 aperture will have very deep depth of field. So, say I am shooting a portrait, and I want to blur out the background. I will choose a large aperture, which means smaller f-stop number. If I am shooting a landscape and want very deep depth of field, I will choose a small aperture, which means larger f number. In the old days, these whole stop apertures were all that your camera might have offered, but digital cameras offer apertures in 1/3rd-stop increments.

So what you will see on your camera is a progression like this. This aperture depth of field thing can be a difficult thing to learn, because you can't reason it out on your own without knowing a lot of physics and math. Again, over time, you will simply learn all of this by rote. If you wear glasses though, you have got kind of a built-in reference card for remembering whether smaller apertures yield more or less depth of field. Here is how it works. You've got to take your glasses off, so now I can't see anything. If I take my finger and curl it up into a tiny little aperture, a little hole, and look through it, the world will be much, much sharper.

What's going on here is I am giving myself a tiny little aperture, and that's dramatically increasing my depth of field. I am actually turning my eye into a pinhole camera. One of the kind of defining characteristics of pinhole photography is that pinhole pictures have infinite depth of field, because a tiny little aperture gives you infinite depth of field, and that depth of field correction is what's allowing me to see. But now, it's time to actually learn how to control the aperture in your camera.

Show transcript

#### This video is part of

Foundations of Photography: Exposure

64 video lessons · 86339 viewers

Author

Expand all | Collapse all
1. ### 1. Introduction

8m 45s
1. Welcome
1m 57s
2. What is exposure?
4m 8s
3. A word about camera brands
2m 40s
2. ### 2. Exposure Fundamentals

9m 31s
1. What is a camera?
2m 52s
2. The shutter
3m 53s
3. The aperture
1m 33s
4. Exposure defined
1m 13s
3. ### 3. Camera Anatomy

13m 50s
1. Modes
2m 7s
2. Pressing the shutter button
2m 54s
3. Autofocus
5m 22s
4. Light metering
2m 3s
5. White balance
1m 24s
4. ### 4. Shutter Speed Fundamentals

29m 26s
1. Shooting sharp images
1m 58s
2. Noting shutter speed
4m 3s
3. Taking control of shutter speed
1m 30s
4. Stop defined
2m 50s
5. Shutter priority mode
4m 34s
6. Exercise: Shutter speed
40s
7. Reciprocity
3m 13s
8. Controlling motion
7m 8s
9. Shutter speed increments
2m 21s
10. Exercise: Go work with shutter speed
1m 9s
5. ### 5. Aperture in Depth

26m 2s
1. Depth of field
1m 53s
2. How aperture is measured
2m 42s
3. Aperture priority mode
4m 57s
4. Lens speed
53s
5. Shooting deep depth of field
3m 53s
6. Shooting shallow depth of field
2m 50s
7. The depth-of-field preview button
4m 24s
8. How shallow should you be?
2m 47s
9. Exercise: Go work with aperture
1m 43s
6. ### 6. Working with ISO

16m 26s
1. ISO: The third exposure parameter
6m 27s
2. Assessing your camera's high ISO
5m 32s
3. Shooting in low light
3m 32s
4. Exercise: Shooting in low light
55s
7. ### 7. White Balance

14m 30s
1. White balance controls
5m 37s
4m 25s
3. Shooting raw
4m 28s
8. ### 8. Metering Modes

6m 3s
1. How light meters work
1m 47s
2. Why are there different modes?
4m 16s
9. ### 9. Exposure Compensation

33m 58s
1. Exposure compensation
4m 0s
2. Intentional overexposure
2m 40s
3. Intentional underexposure
1m 42s
4. Controlling tone
2m 31s
5. The histogram
10m 4s
6. Real-world histograms
5m 49s
7. Tone and color
2m 16s
8. Auto exposure bracketing
3m 57s
9. Exercise: Go work with exposure compensation
59s
10. ### 10. Dynamic Range

12m 56s
1. Dynamic range
2m 24s
2. Exposing for highlights
4m 15s
3. Fill flash
3m 11s
4. Three solutions to the same problem
3m 6s
11. ### 11. Manual Mode

12m 26s
1. Manual mode
2m 6s
2. Manual mode and light meters
4m 52s
3. Manual exposure exercise
5m 28s
12. ### 12. Advanced Program Mode

12m 1s
1. Custom modes and A-DEP
1m 39s
2. Program shift
3m 52s
3. Exposure compensation with program shift
1m 58s
4. An exercise in reciprocity
53s
5. Scene modes and in-camera processing
3m 39s
13. ### Conclusion

8m 15s
1. Shooting with post production in mind
3m 45s
2. Exposure strategy
3m 51s
3. Goodbye
39s

### Start learning today

Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold
Share a link to this course

### What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

### Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.

Exercise files

How to use exercise files.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.

Congratulations

You have completed Foundations of Photography: Exposure.

Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

How to use exercise files.

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

• Mark video as unwatched
• Mark ALL videos as unwatched
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

## Are you sure you want to delete this note?

Thanks for signing up.

We’ll send you a confirmation email shortly.

• new course releases
• general communications
• special notices

Keep up with news, tips, and latest courses with emails from lynda.com.

• new course releases