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Canon Lenses: The Complete Guide

Lesson 21 of 58

Canon Lens Shape


Canon Lenses: The Complete Guide

Lesson 21 of 58

Canon Lens Shape


Lesson Info

Canon Lens Shape

So we got our glass compounds. We've got the glass that we got the type of glass we're gonna do now. Once we have this, we need to shape it all right. Now, most lenses are gonna be shaped into a spherical, rounded type element and that works out well for most lenses. We can you do that most of the time and it's gonna come out fine, but from time to time, depending on the chemical compound, depending on the way the light travels through. Here are red, blue and green points of light. Don't end up in the right area. How do we fix this? Well, one of the solutions is to create an ass spherical element that has a non perfectly smooth exterior. It's it is smooth, but it's not a rounded in the way that a spherical forms of sphere alright. And by doing that, if they do it just right, they can fix this problem. So this could potentially reduce spherical aberrations astigmatism, and it can also reduce the number of elements, which means we can make a smaller lands. You'll find these in white angl...

es, lardo, large aperture lenses and compact zooms where they're really trying to reduce the size of the lens quite a bit. And so there's a long list of lenses that are using this aspirate kal glass. And as I say, I'm not involved in the process of making. But I would think polishing a spherical element is a whole lot easier than an astrological one, because the types of machines they have will take, like, 40 lenses in them and just be kind of rubbing them all around, smoothing them all up when it comes to ask Miracle. It's a whole different system that they had to develop in order to work with these types of glass elements. And so there are different types of s mericle elements, ground and polished. That sounds pretty good to me. Molded glass not quite as good, so they just kind of form it in that shape rather than grinding it down. And then there are precision moulded plastics that they will use, and that's more likely to be found in some of their point and shoot and smaller in cameras. And so they are technically plastic lenses in there, which some people are very concerned is that a glass lens or plastic lens. Well, you know what that they could do with plastics. They could make him as good or better than standard glass. D o stands for diffraction optics, and it's only used in a couple very unique, very special lenses from Canon. So one idea says, we're all designing our lenses right is Excuse me. What if we just made everything smaller when it that I mean OK, here's our big lands. Let's just make the lens and all the lens elements smaller. What's the problem with that? Can't we just reduce everything? Well, if we do that, it's quite possible that are light rays once again, do not end up at the same point and we're not getting sharp focus. So nice idea. Just reduce everything, make everything half the size and it will work doesn't always work that way. So another solution that they found was a diffraction of scratch structure, and they found that this was fairly good, and they could use this to focus the light in on the sensor and get a pretty good image out of it. But it wasn't perfect. Perfect. Some of the light dispersed off to the side. How do we fix this out and what they're currently using is they're using a dual layered, multilayered refractive structure that corrects for these problems. Redirects light properly in, and they're able to reduce the size of the lens significantly in some cases in order to get a nice, sharp image. So they designed a 400 millimeter F four lens, and they said, You know what? This thing is going to be 31.7 millimeters in length. They know this stuff ahead of time, exactly what they're going to need. But we want to design something that is significantly smaller with these new optics. And this is how they came up with their 400 d o. D fractal optic lens. They just introduced their second version of this. And if you compare what a normal 400 is versus the D O, it is a big savings in size and in wait. So 27% smaller, 31% lighter in size. Very nice thing to have. You will also find this in another lens that they have. They have a standard 72 300 lands pretty typical. It's 14 centimeters, almost six inches in height. They do have a triple layer Dio design in their 300 d Oh, let's 30% smaller, 18% lighter. This is all well and good, but life is not perfect in the world of D. L. Because of the way the lenses air cut, he will sometimes get flare issues that don't look like flare from a normal lens. And they can't just implement this on every single lens. It just doesn't work out, which is why we don't see it on everything out there. There's only this compact zoom. There is the old 400 the new 400 which, by the way, is much sharper than the old one that has this dio technology. They kind of let it lie dormant for about 10 years, and I kind of wondered if they were going to do anything more with it. Because, optically speaking, the 400 the 72 300 are among the weaker canon lenses when it comes to sharpness and overall image quality. And so it's not a perfected technology, but I will have to say that the 400 F four and all the image tests that I've seen is pretty darn phenomenal. It looks really, really good. And so maybe they have kind of figured out any of the little bugs in there because it's looking really good these days on that latest lens, at least so that's a special lens designed for those lances.

Class Description

Working with interchangeable lenses can be both exciting and daunting to all levels of photographers. Canon® Lenses: The Complete Guide with John Greengo will prepare you to select the right lens and get the most out of all of your lens investments.

John Greengo is the master of making complex photography concepts easy to understand and in this class, he’ll bring all of your Canon EOS DSLR lens options and operations into focus. 

You’ll learn about: 

  • Focal length and aperture
  • Canon zoom lenses
  • Which lens accessories to buy
  • Third-party lenses
  • Maintaining a lens system

John will cover the full range of Canon lenses, from ultra-wide to super-telephoto, zooms to primes, fisheye to perspective control. You’ll learn how to match the right lens to your needs and get insights on the best ways to use it.

Whether you are thinking about buying a new lens or just want to get the most out of what you already have, Canon Lenses: The Complete Guide with John Greengo will help you out.


  1. Class Introduction
  2. Canon Lens Basics

    John Greengo gets you up-to-speed on the basics of working with interchangeable Canon® lenses.

  3. Focal Length: Angle of View
  4. Focal Length: Normal Lenses
  5. Focal Length: Wide Angle Lenses
  6. Focal Length: Telephoto Lens
  7. Focal Length Rule of Thumb
  8. Field of View
  9. Aperture Basics
  10. Aperture: Maximum Aperture
  11. Aperture: Equivalent Focal Length
  12. Aperture: Depth of Field
  13. Aperture: Maximum Sharpness
  14. Aperture: Starburst Effect
  15. Aperture: Flare
  16. Aperture: Hyperfocal Distance
  17. Camera Mount System
  18. Canon Lens Compatibility
  19. Canon Lens Design
  20. Canon Lens Composition
  21. Canon Lens Shape
  22. Canon Lens Coating
  23. Canon Lens Focusing
  24. Lens Autofocus
  25. Canon Lens Image Stabilization
  26. Canon L Lenses
  27. Image Quality
  28. Canon Zoom Lenses: Standard
  29. Canon Super Zooms
  30. Canon Wide Zooms
  31. Canon Telephoto Zooms
  32. Prime Lens: Normal Lenses
  33. Prime Lens: Moderate Wide
  34. Prime Lens: Wide Angle
  35. Prime Lens: Ultra-Wide
  36. Prime Lens: Short Telephoto
  37. Prime Lens: Medium Telephoto
  38. Prime Lens: Super Telephoto
  39. 3rd Party Lenses Overview
  40. 3rd Party Prime Lenses
  41. 3rd Party Zoom Lenses
  42. Lens Accessories: Filters
  43. Lens Accessories: Lens Hoods
  44. Lens Accessories: Tripod Mount
  45. Lens Accessories: Extension Tubes
  46. Lens Accessories: Extenders
  47. Macro Lens: Reproduction Ratio
  48. Macro Lens: Technique and Choices
  49. Fisheye: Technique and Choices
  50. Tilt Shift: Techniques and Choices
  51. Make a Lens System Choice
  52. Choosing A Portrait Lens
  53. Choosing A Sports Lens
  54. Choosing A Landscape Lens
  55. Best Lenses for You
  56. Lens Maintenance
  57. Buying and Selling Lens
  58. What is John Greengo's Favorite Lens?



I so appreciate what a good teacher John is. I wish I would have known this much about lenses when I first started out buying my lenses. It was hard finding information about lenses. I didn't want to spend money on a lens I wouldn't use. The better understanding we have about our gear the better photographers we will be. I have never seen a class like this. Invaluable...yes I bought the class! I am really impressed with the high quality photography classes available on Creative Live!

a Creativelive Student

Have loved the other John Greengo classes I've watched & purchased - and this is another winner! Having been a high school/college science teacher, it is refreshing to take a course with someone who not only is extremely experienced, seems to be a computer having stored so much knowledge, but is equally concerned about making the information truly understandable to different levels. And he shares the information using every tool he can: slides, video, interactive presentations, and great quizzes. I learned so much about my Canon lenses - and lenses in general with their many components. I am excited about testing each of mine to see what macro ratio they handle, and especially appreciated the tutorial on testing each for their specific quirk that affects super sharpness. This class is great whether you own Canon lenses or not. Thanks John Greengo!


This was a great class not just about the lenses that Canon offers but also how each lens works. As usual, John's slides are alway informative and entertaining. There is a phrase: John has a slide for that! I am not even a Canon user and found this class to have great information for the use of each specific lens. Great work John! Thank you Creative Live for another great class!