Focal Length
John Greengo
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
Focal Length
Alright. We're gonna talk about the focal length of the lens. This is what you see from side to side in a lens, and it's the lens's most important characteristic. And so we're talking about our angle of view. We're gonna talk about the different types of lenses in here. I've grouped 'em into normal lenses, wide lenses, and telephoto lenses. Now for this section, it doesn't matter whether you have a prime lens or a zoom lens. All that matters is that you can get to that number that we're talking about. So, let's talk about those numbers. If we have a camera, and we have a 50mm lens on it, with a full-frame camera this is what we're gonna see from side to side. As we see more from side to side, we're getting into the world of wide-angle photography. And there's moderate wides, there's just kind of normal wide angles, and then there are ultra-wide angles when you get wide enough. When you see a narrower angle of view, you're talking about a telephoto lens. And they will sometimes be refer...
red to as short, medium, or super-telephoto lenses. Now, all the numbers that you see on screen in red here are in relationship to what you would see with a full-frame sensor, because remember, in the previous section, I said that that is the standard that most people, including myself, are gonna be talking about lenses. But I know, 'cause I've taught a lot of classes, that most people in photography right now with interchangeable lenses are using a cropped frame sensor, very similar to ones used in Sony and Nikon and Canon. And so they're gonna have about a 1.5 to 1.6 crop factor. So if you have one of those cameras, you may wanna pay more attention to the blue number on the bottom, because to get that angle of view, that is the lens that you would need in there. Now, if you wanna measure what you can see with a lens, there are multiple ways of doing it. You can measure, if you want, horizontally, you can measure diagonally, vertically. And the way that I'm gonna be doing it for my class is horizontally, 'cause that's how people usually hold the camera, and they kind of think straight from side to side across. What do you see from side to side? So let's take a look at what different lenses look like in one of my favorite photographic locations, is the road down in Arizona that leads to Monument Valley. And so I gotta be careful about this, but if you were standing out in the middle of the road with a 50mm lens, this is a very realistic look of what it looks like to look down this road. Now as we go into the world of wide-angle, now remember, full-frame users look to the top of the screen, where we're talking about focal length, and the crop-frame users, over to the right-hand side, and if you have a micro 4/3 system, you take the top number and you divide it by two. They have a little extra math homework on them for this project here. So we're gonna go into the world of wide-angle. 35 is considered a modestly wide lens. As many of you know, 24 is one of my favorite wide-angle lenses, an I'll talk about that more in a little bit. But one of the things you'll notice as we go to 16mm and ultra-wide is, look how much foreground takes up the scene, compared to where we were in the 50mm. So one of the things we'll talk a lot about in wide-angle lenses is foreground material. And this is very important to landscape photographers, 'cause they're often looking for flowers and bushes and rocks and sticks and branches to photograph in the foreground along with a beautiful background in there. So, we're gonna zoom back up to 50mm, going through our equivalents here, modestly wide, back to our normal lens at 50. And we're gonna enter the world of telephoto. So 100mm would be considered a short telephoto lens. And let's get ourselves up to 200, where we can start seeing some compression. Now this is when you are using a longer telephoto lens. The compression effect is much easier to see, 'cause it's happening all over the frame. Now that road that you're looking at onscreen is very far from the butte in the background. It's about five miles from there. And compression refers to the fact that you're looking at two objects that look like they're kind of compressed together. And you're gonna get that very clearly when you're shooting with two, 400, and even longer lenses. So let's go ahead and bring this back down to to get our normal view once again, and we'll be able to see what our crop factor was at 100, 200, and 400. So all these different lenses are just simply different angles of view for telling different types of stories. And each one is good at something that's a little bit different.
Class Materials
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