Canon® Lenses: The Complete Guide

Lesson 24 of 58

Lens Autofocus

 

Canon® Lenses: The Complete Guide

Lesson 24 of 58

Lens Autofocus

 

Lesson Info

Lens Autofocus

I've been dealing with focus let's do the world of auto focus so in this case we're gonna have these little contacts which connect up with the electronics on our camera and there's different numbers according to what lens and what needs they have it typically has to do with whether they use their used with tele converters or not you'll seymour these contacts when they're used with tele converters and so this is what is transmitting data information as well as power from the cameras to the lands and so motors for focusing are built into the lands and their optimized according to the needs of that lens which is why they went with this whole e f system 00:00:41.25 --> 00:00:44. proximity equals efficiency the closer the motor is 00:00:44.63 --> 00:00:47. toe where it actually needs to do the work means the 00:00:47.36 --> 00:00:49. more efficient it will need to be better battery life 00:00:51.35 --> 00:00:53. it will be able to be used with different extenders 00:00:53.25 --> 00:00:55. w...

hich is reasons why they went with the system their 00:00:55.97 --> 00:00:59. original focusing system is an ark form drive system 00:00:59.52 --> 00:01:01. we're not going to get into the specifics of it because 00:01:01.21 --> 00:01:04. we don't need teo but in a very general sense they 00:01:04.72 --> 00:01:08. were slow and noisy and they sounded like a squeaky 00:01:08.67 --> 00:01:11. wheel and so if you get one of the older lenses it 00:01:11.92 --> 00:01:13. doesn't sound nice and smooth 00:01:15.35 --> 00:01:18. and there was no manual focus override when your camera 00:01:18.0 --> 00:01:20. was in auto focus you couldn't grab the focusing ring 00:01:20.94 --> 00:01:24. and just start turning. You had to use the manual 00:01:24.46 --> 00:01:27. switch to get it over into the manual. The next little 00:01:27.25 --> 00:01:29. improvement they made is they made it into a micro 00:01:29.6 --> 00:01:32. motor, which reduced the size of it, and reduce the 00:01:32.86 --> 00:01:34. price of it a little bit. And they were able to put 00:01:34.9 --> 00:01:37. it in some of their cheaper lenses. And so this is 00:01:37.76 --> 00:01:39. something that you might see on some of their very 00:01:39.55 --> 00:01:40. old lenses. 00:01:41.55 --> 00:01:43. And this is a very traditional electric motor, just 00:01:43.72 --> 00:01:46. driving a gear train. So it's, fairly traditional 00:01:46.42 --> 00:01:49. technology. No manual focus over, right, either. So, 00:01:49.22 --> 00:01:51. if you're in auto focus, you gotta flip the switch 00:01:51.51 --> 00:01:53. in order to manually focus the lens. And there still are two lenses out from the original 00:01:59.92 --> 00:02:03. cast of characters who introduced the f system there, 00:02:03.1 --> 00:02:05. fifty two point five micro and their one thirty five 00:02:05.3 --> 00:02:08. to eight soft focus there. Not real common. They should 00:02:08.67 --> 00:02:11. really, really be replaced or something. But they're 00:02:11.42 --> 00:02:13. still using these older motors there's. A few of the 00:02:13.85 --> 00:02:16. lower end lenses that air using these micro motor 00:02:16.19 --> 00:02:18. lenses. And they're all lenses that are going to be 00:02:18.55 --> 00:02:21. kind of on the second tier of auto focusing quality. 00:02:21.84 --> 00:02:24. So these this list of lenses down here in the lower 00:02:24.36 --> 00:02:27. left corner, not my first choice. If I was going to 00:02:27.31 --> 00:02:28. be shooting professional sports, 00:02:29.66 --> 00:02:30. may be my last choice. And then everything got better with us em ultrasonic motors are these very fast and quiet focusing motors and they started with a ring type you sm or a ring us um and then they modified it and called it a ring type us and we're not going to get into the details of it but it's what they're currently using even in their up to date lenses they didn't making a smaller version of it and then they made a smaller, improved version of it but it's the ring type usm that is in most of the lenses that are being made today and the reason they went with this type of system it is very quiet is very fast it has a lot of torque so we can get up to speed very quickly it's very efficient so it's good on battery power it's small in size it can go fast, it can go slow and it works under a wide number of conditions and it allows us to manually grab the focusing ring and move it whenever we want. And so this is kind of the standard for focusing and this is what other companies have followed in and this technology hasn't really changed that much, so there haven't really made improvements they've made some ways of making it smaller and cheaper, but the basic good ring type usm hasn't changed much at all in the last twenty years so there are a few lenses that air using their smaller cheaper version of their focusing motor this there's this junior version and it is really hard to find factual data on what motors aaron the lens because this says ultrasonic but it's actually using the micro ultrasonic motor and I have dug in and I've got all the information and when you get the class you get the notes that have all this information in there in case you're wondering and so this this seventy two three hundred you can't just grab this focusing ring and turn it whenever you want because when it's an auto focus the gears are engaged and you start burning the motors and it's not a good thing now they did make a special exception these are the only two lenses still using the micro us and motor is that on the fifty one for it does employ a special clutch in there that allows you to just pick that lens up and manually focus whenever you want. However this lens is notorious for having focusing problems because it's using this old focusing motor with the special clutch system so if you talk to somebody who's out of fifty one for you'll probably hear about kennedy you have personal experience with this I did I did have that lens and of even versus you know the one point eight it had, you know, some tough focusing issues there, so it is a truth game it alright didn't just make this one up all right so the latest one that they've introduced is thie s t m the stepping motor mabel sometimes advertises as smooth transition from ocean if you remember when we were talking about still photographers versus cinematographers and their needs for focusing are different because as a still photographer I don't care what happens between focusing on a and focusing on b but for shooting movies it's really important that it's smooth and these ultrasonic motors that are great for still photographers they're not so smooth and the focusing their just quick and these are much smoother and they are a little bit better for shooting movies in an amateur since this's not what the professionals or shooting with and so they're fairly quiet the ultra sonics required as well but mainly it seems like these were designed so that you could focus while you were shooting video and it had a smoother focus back and forth and so this would be more for mom and dad filming the kids down at the park just you know you have your dslr you want to shoot video you want to shoot auto focus while you're shooting your video for home movies then that's going to work out quite well the sdm motors work fine for that for still photography the motors are a bit of a toss up as to how good they are I would take a u s e m over an s t m any day. The question is, is what? I want this over something else. And it's. Okay, it's, just not. It has one feature that I'm not particularly fond of, which is a fly by wire manual focusing system, which means when you turn the manual focusing, you're not actually directly engaged with the lenses. You're turning electronics, which is telling the lens to move. Move so there's a slight delay as you do it. It's not quite directly linked to your finger movements. And so, that's. What this focus by wire is and one of the downsides of this is that when you leave your camera turn, if you have your camera turned on, you focus. And then you turn your camera off. You're like, oh, I need to focus back to infinity. I want to retract the lens. It won't work because there's no power to the lands and to manually focus. You have to have power to the lens when this has turned on. And so the sdm lenses is relatively short. But they seem to be employing the sdm focusing system on all their new, lower in lenses. And so I think this is their new de facto focusing system for their lower in lenses. So full time manual focusing. This is a great feature. It was one of the big hits in the early days of auto focus. With cannon, the lower in lenses do not have this. What this enables you to dio is that if you are in auto focus, you can just grab that focusing 00:07:57.514 --> 00:08:01. ring and turn it whenever you want and it's not going 00:08:01.24 --> 00:08:03. to damage the lens, and you, khun, smoothly. Focus 00:08:03.55 --> 00:08:06. it as you wish. And so this is a great feature, it's, 00:08:06.8 --> 00:08:09. something that's going to be on their medium toe higher 00:08:09.21 --> 00:08:09. in flynn's us.

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.

Lessons

  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?

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