The AF-ON & Back Button Focus
Let's now talk about back button focus. This button here is called the AF-ON button, and again higher end cameras have an AF-ON button. Lower end cameras don't have an AF-ON button. But you can program the lower end cameras to use what's called the AE lock. Let me just grab this camera, I'll bring it back to the show center. This camera here is the Nikon D and you'll see it doesn't have an AF-ON button, but it does have an AE lock button. So we can program that to work the same way though, we can program that to be AF-ON. And the way you do that on the D750, I'll just show it here really quickly, is we go into the pencil menu, and we go to autofocus, I'm sorry not autofocus I made a mistake, we go down to controls, and we go down to Assign the AE-L AFL button, and then we tell it be an AF-ON button. So just program this here to be AF-ON, alright. So now the next thing I'm gonna teach is how we use that button. On the D500 we also need to program it, to program it properly I'll go throu...
gh that in just a second. But before I do I just wanna give you an illustration. So let's say that we're photographing a bird. In fact to do that I'm gonna fast forward two slides here real quick, so we're photographing this bird. When the bird is in flight, I need to be pressing the AF-ON button. So I'm pushing the AF-ON, in fact I have that here in the slide, you'll see. While the bird is flying, I'm actually pushing AF-ON, cool. I'm tracking in continuous servo autofocus. Now when the bird stops and the bird lands, I need to stop tracking focus. So I let go of the AF-ON button. It's very, very helpful, because now when I let go I can now take a picture and when I push my shutter release the camera doesn't focus again. In other words, if my sensor would've been up here, in the old school way of front button focus, the sensor would've then focused maybe out here on the water. But now that it's deactivated, the front button is no longer focusing, I can shoot all day long and not have to refocus. So it's actually a very cool way to shoot. It's a much more efficient way to do autofocus. So let me show you how we set that up here on the Nikon D500, and then I'll go back through one quick summary, and then we're actually gonna do a studio shoot with a model to demonstrate how back button focus works. So D500 now, now what we're gonna do is we're going to go into the pencil menu, and we're gonna change a couple of menu options. We're gonna go into the autofocus section here and the first one is, remember we wanna be in AF-C priority, we wanna set that one for release priority. That's important here because we want the camera to take the picture as soon as we press the shutter release. So that's the first one. The next one is we need to go down to menu A8, A8 stands for autofocus activation. Here we're programming in what do we want to activate focus. If I choose the top setting, that's shutter release and autofocus-on button. In other words both of them will activate focus. So if I use that, then the front button will focus and the back button will focus. And that's not what we want to do for back button focus scenarios. So here I'm gonna say AF-ON only, and if I move the words around, it will say only the AF-ON button activates focus. So there we go. So that's ready to go. The release priority's ready to go, and there's one more thing we have to change. We have to go to your buttons and controls, and that's in letter F. So go down to pencil, F, and we're gonna choose assign, I'm sorry we're gonna choose custom control assignment, and AF-ON button, so here we're telling the camera what's the general function of the AF-ON button, and in this case we want it to be AF-ON. We want the AF-ON button to be an AF-ON button. Sounds funny but you need to tell the camera. Alright so there we go, AF-ON. I'm gonna go back to the keynote, back to the presentation here, and back up one slide. So this method that I'm gonna show here works for sports, it works for landscapes, it works for flowers, it works for portraits, travel, just about anything. And again, here's the approach. The approach is any time the subject is moving, you're pushing the AF-ON button okay, tracking the subject in and out. Any time the subject stops, you're taking your thumb off and you're just taking a picture. And now you can recompose left, and recompose right, and the camera won't refocus, that's really powerful. It's actually much more powerful than you might first imagine. So I encourage you if you're gonna practice with this to try it and use it for an entire month. That's how long it takes to get familiar with this. If you try it for like an hour or half a day, it won't become natural, this has to become second nature to you. So practice it for a while. Any time the subject's moving, focus, any time the subject stops, let go, and then just take your pictures at any time that you want in there. So, we ready? Let's do an example. We're gonna bring our sports model over here, come on over. Welcome.
So what I'm gonna have you do is something very simple. I'm just gonna have you stand kinda over here, and the first thing we're gonna do is I'm just gonna have you walk, so just kinda walk towards me like this, and then walk backwards, and just do this maybe three or four times, and I'm gonna be talking through it, and don't worry so much about posing or any other details, just to show the movement. Before she starts though, I'm gonna reiterate. So, I'm in AF-C mode, so I'm in autofocus continuous, yes. I'm gonna choose dynamic focus, and this is the D500, so I'm gonna use D72. Now I'm gonna move my sensor up towards something on her that has contrast, and she actually wore great clothes today. I have to confess, I was able to dictate what kind of clothes she wore, and I said you know what, I know that my subject needs to be in good light, we need to have contrast and we need to have distinct lines. So you can see her clothes, I've got lots of distinct lines on her clothing which is great for autofocus, fantastic. So she's gonna walk towards me and while she's walking I'm just gonna push and hold down my autofocus-on button. And while she does that, I'm gonna be taking pictures. Alright go for it. (shutter clicking) Good, and the system's tracking. Okay go ahead and walk back. And yeah that's great, actually turn around and just walk backwards that way. There we go, perfect. Great, alright this time we're gonna do the same thing and this time I want you to walk just a little bit faster okay? So that, I'll say that was easy for the Nikon camera to do, she's walking very slow, these new cameras can track that no problem. This time I want you to walk at a brisk walk, and go ahead and stop two or three feet in front of me. Alright, here we go. Go for it. (shutter clicking) Okay walk back. Alright, cool. So hold that for a second. Now I'm gonna go back through my photos and I'm gonna look at 'em, and see if I nailed all these shots. They're looking pretty good. She's looking in focus. Awesome, really fantastic. Go Nikon, and as I said earlier, skill trumps gear just about any day of the year. I have practiced with this a lot and I understand how the autofocus system is working, so therefore I'm getting really great results with the system. To give you a little more detail, I actually moved the sensor up in the frame so that it's on her face, awesome. Okay. Now let's do something else, now I'm gonna pretend that you're playing soccer okay, and while she's running around playing soccer, you just can like move left and right, then what I want you to do is I want you to stop, and I want you to pretend like you're having a conversation with a coach over on the sideline, okay. This is a really common thing to do in your photography, where you're getting movement and action with the person moving, and then they stop and you're like oh here's a great little environmental portrait. So go ahead and bounce around a little bit, whatever you're gonna do. Great, cool, alright, nice. Alright coach blow the whistle, okay go ahead and stop. So now she's having a conversation with the coach. So here's what I wanna do as a photographer. I now wanna zoom in on her, so I do that by pushing my AF-ON button, focus on her face, now I can let go with my thumb, I can recompose, and put her on the left side of the frame so that it's more like the negative space is in front of her. So you see how that worked, any time she's moving, go ahead and move around again, I'm pressing, okay, and any time she's stopped, I go up, I finish on her face, let go, and now I can put her on this side or this side. The beauty of back button focus. So cool, so efficient. She's moving, I'm pressing. She's stopped, I stop. There you go, back button focus. Thank you. We'll have you back here in just a few minutes. Right on. So back to our bird photo here. I use this for wildlife photography, I use it for flowers, I use it for all kinds of scenarios. In fact just to make sure that everybody understands how this can be so useful, let's pretend I have a flower, I'll pretend my little water bottle here is a flower, and I'll set it on the floor here, make the camera guys work. To work this photo with back button focus, here's the way it works out. I focus on the flower, (clicks tongue) with my thumb, I let go, and then I can compose up or down a little, (shutter clicks) and then take the shot. That easy. So isn't it strange I'm in AF-C mode, remember that I'm in autofocus continuous mode, I'm in a continuous servo, but I'm taking a photo of a stationary object. And the reason I'm able to do that is because I have deactivated the focus control from the front button. So focus on the flower, let go, take the picture. Now if the flower starts running towards me, or moving or whatever and I need to go back into a dynamic focus scenario, all I gotta do is push and hold my focus button. It works for landscapes just as well. Imagine I am photographing this landscape, I've got rocks and a lake and a mountain, now I'll use maybe a small aperture like F/16, I focus down low with my thumb, I let go, I then recompose to get the mountains, and then pow take the shot. So back button focus, it works for just about any type of photography, in fact I don't think I've ever found a scenario where back button focus doesn't work as well or better than front button focus. So use it, you're gonna love it.