Lessons
Class Introduction
05:06 2Lens Basics
10:55 3Focal Length
04:43 4Normal Lenses
10:14 5Wide Angle Lenses
09:24 6Telephoto Lenses
11:43 7Lens Comparisons
08:33 8Aperture
11:26Equivalent Aperture
04:07 10Depth of Field
05:25 11Maximum Sharpness
02:58 12Hyperfocal Distance
09:33 13Mount System & Lens Grade
04:03 14Lens Design
11:36 15Compatibility
17:29 16Lens Technology
05:21 17Focusing & Stabilization
06:39 18Image Quality
04:46 19Standard & Super Zoom
04:52 20Wide & Telephoto & Super Telephoto Zoom
07:48 21Prime Lenses
06:06 22Short, Medium & Super Telephoto Lenses
05:35 23The Macro Lens
07:14 24The Fisheye Lens
10:24 25The Tilt & Shift Lens
10:59 26Filters
06:34 27Lens Hoods
04:02 28Tripod Mount
02:42 29Extension Tubes
03:26 30Teleconverters
03:11 31Making a Lens Choice
04:15 32The Portrait Lens
08:44 33The Action Lens
11:23 34The Landscape Lens
06:51 35Lens Maintenance
09:40Lesson Info
Equivalent Aperture
This is something that I did not learn about in college, because when I was in college, we shot with 35 millimeter cameras, and we shot with four by film cameras, and they were completely different, and we never talked about equivalent aperture. But now that we have cameras with different-sized sensors and a variety of different lenses, we want to talk a little bit about the aperture equivalents, because in the previous section, we were talking about the focal length equivalent. So let's take a couple of lenses. We've got a full frame camera on the left that is shooting with a 50 millimeter lens. Over on the right-hand side, we're shooting with a 35 millimeter lens, to get the same 40 degree angle of view. So, is the photos that you take with these two cameras exactly the same? Well, the angle of view is the same, and let's take a look at what lenses, say if we were using the 50 millimeter 1.4 and the 35 1.4, well then we would be letting in the same amount of light. But they're differ...
ent lenses, and so things are gonna look a little bit different. And where things are different is in how shallow the depth of field is. The 50 millimeter lens is gonna render a shallower depth of field than a 35 1.4, even though it sees the same angle of view. Angle of view and depth of field are different subjects. And so, if we stop the 50 millimeter lens down to f/2, then they start to look very, very similar. Now this is a subtle difference to people who are kinda just getting into photography, but as you get more and more into photography, you're gonna notice a particular look from a particular lens. Let's try this with a 300 millimeter lens on a full frame camera and a 200 millimeter lens on a crop frame camera. These are gonna be shot at f/5.6, so they're gonna have the same amount of light coming in, but we have a different-sized sensor. And the lenses are gonna render differently. If you look at that tree in the background, you'll notice, with the full frame camera, you are getting a shallower depth of field lens. If we stop it down to f/8, it's a little bit closer to the 200 at f/8. And so as we stop these lenses down, the full frame is always going to give you a shallower depth of field. Now, some people will immediately assume that a shallower depth of field is better. Well, not necessarily, sometimes it is, sometimes it's not. And so it depends on what you're going to shoot. And so, there's a lot of forums and places where you can talk about photography these days, and one of the most common arguments is about equivalence from one size sensor and lens to a different size sensor and lens. And so if you have a full frame camera with a 50 millimeter 1.4, it sees the exact same angle of view, roughly, as a 35 1.4 on a crop frame camera. They let in the same amount of light, and you're gonna set the same shutter speed to get the same exposure. What's different is the depth of field that you get, because a 50 millimeter lens will have shallower depth of field than a 35, the depth of field will be different. And so the same aperture gives you the same low light ability, the same focal lengths give you the same depth of field. In these examples, we have different focal lengths that are gonna give you a different depth of field. And so when people are saying, I have a lens on my crop frame camera, and it's the equivalent to something like, something else, somebody's likely to get mad and say, it's not the same! Well you can say, it gives me the same angle of view, and it gives me the same aperture opening, but a different depth of field. And so there's three characteristics, there's the angle of view, there's the aperture, and the resulting depth of field. And when we talk about equivalence with crop frame cameras, you can get two of them the same, but that third one is a little bit difficult to get to. You have to get a different aperture to get the same depth of field. So it's a little complicated but you'll learn it as you practice it and continue shooting.
Class Materials
Bonus Materials with Purchase
Ratings and Reviews
E.L. Bl/Du
John is one of the best instructors Ive watched. he's clear, concise, and gets right to the point. His display's and diagrams are so great, he makes very complicated subjects easy to understand, and fun. He holds your attention and interest b/c everything he says is valuable. This really helped me understand the vast complicated world of lenses. I would highly recommend this class to anyone who doesnt know what hyperfocal distance is.
Boris Dimitrov
Excellent class packed with incredibly useful knowledge. John is an amazing lecturer. He has also developed really great materials to help explain all the concepts and technologies that are explored in the class. Looking forward to my next class with him!
Lettie Turner
Another great JG class, my 4th. He gives a lot of individual attention to several popular lens brands. I really think after seeing this video series you could pick out three lenses that would fit your needs and your pocketbook. The class handout is spot on for what is covered in the video. Great job!! Thank you