Nikon® D750 Auto and Manual Focus
The auto focus system on the camera a little bit confusing in some cases because we have an auto focus switch on the camera and we have one on the lens as well, at least on modern lenses. If you have a lens that's twenty years old, you probably don't have one on the lens and you'll have to use the one on the camera body. But for all the modern users that have all the modern equipment, what I recommend is leaving the switch on the body in a f all the time, and if you do want to manually focus switching the lens switch because that is the direction that nikon is going and it's probably easiest just to leave the one in the body in auto focus all the time. The button in the middle is called the mode button, and I jokingly like to call it the mystery button because it doesn't have a label but it's a really important button for changing the focusing system on the camera, so by pressing this button and turning either the front dial or the back dial, we're going to be able to change two very i...
mportant aspects to the focusing system in the focusing system on this is somewhat complicated in pretty thorough, so we're going to take a closer look at the focusing mode and the focusing area mode first up, pressing the button and then what we're going to do next is we're going to turn the back dial on our camera so that it says a f s and what that means is single servo auto focus, which means the camera is going to be set to focus on a subject and then stop, and that way it allows you to recompose the photograph for different compositional reasons, and so you will be looking at where the focusing points are. We'll talk about those next focus on it, and then it stops the completely different type of focusing is continuous focusing, and this is where the camera will focus on a subject and it will refocus if that subject moves and it will continue to track that action. So if you're shooting sports photography, birds in flight animals, sports, you're going to want to have a camera in the f c mode. Definitely, the camera does also have an a f a mode, which allows you the camera to switch back and forth, and I do not recommend this mode. I do not like this mode, and the reason I don't like it is because it's inconsistent, I have accidentally had my camera in that mode in a situation. On the right, for instance, where I have runners coming in towards me and the camera would lock in on the grass and not the runner because it didn't understand what my subject wass and I think it's pretty easy for most of us to determine. Are we shooting sports or not? If you're shooting sports and action, you want to be in the a f c mode, and if you're shooting most basic photography type subjects, then you're going to want to be in the s mode for single serve. Oh, so that is the focusing mode. Next up is where we choose to focus. All right, next up, we want to look at the area mode and so by pressing that little mystery button on the side, which is really the mode button and turning the front, we're gonna be able to choose where we focus in the frame in which focusing points and we have a lot of options. So let's go through all the options. First off is just a single point. You can choose a point in the middle, you can choose any one of the points that you want. Next up is what's known as d nine now, in order to get this you have to have your camera in the f c mode, so if you're following along at home, you might wantto make sure that your cameras in the fc mode just so that you can see what this d nine looks like, what it is, it's, a it's nine points grouped together, and you can move these groups wherever you want in the frame. I find this to be very good for action photography d twenty one also works very well. I tend to like to have a group of focusing points about the size of my subject. Whatever my subject happens to be, I don't want it to be overly large or overly a song, but d nine, indeed, twenty one would be my favorite systems for doing sports or action based focusing d fifty one will utilize all points, all fifty one, focusing points for trying to achieve focus. Nikon has their own proprietary system that they call three d focusing, and this is where the camera will actually use luminous and color information to try to figure out what your subject is and where you should focus and it can work very well. But it's got a little bit of voodoo that is hard to control in there, and so many professionals don't really like this because it's a little bit unpredictable on what it's trying to dio and so you could test it out, see if it works well for what you're doing. If not, I would go back to the d nine or d twenty one in most cases, one of the things that was new in this camera, that a lot of previous cameras didn't have its kind of trickled down from the deed for which is a group point, which is really dumb, that they call it group because it's, really d five or defore, depending on how you want to think about it, it's just a smaller group of pix of points to focus on and sew it. I really think of this as like a d five because you're choosing one point and force surrounding areas to kind of help in the focusing of it. And then finally, we have auto, which uses all fifty one, and if you look at these carefully, you might say, well, john what's the difference between d fifty one and auto because they're both using all fifty one points. The difference is, is in the auto mode, it uses all fifty one, and it we'll focus on whatever subject is closest to the camera in all fifty one points and so that's kind of the generic dummy mode. On the camera, if you were to put it in the full auto mode, that is the mode that the camera would be, and it works pretty well most of the time, unless you have something in the foreground that you didn't want to have in focus with d fifty one the difference is, is that you get to choose the first starting point where you want the focusing to start activating so let's just say you're focusing on a runner coming around a track, and they're coming around the left hand side of the track. You could activate one of those focusing points on the left hand side and it's the runner moves around towards the middle and towards the right side of the frame. It would track that subject moving around and it's a very good system. If you want to track a subject that's moving a great distance through out the frame, and so if you're going to hand the camera to your brother or sister, who doesn't know how to work your camera than the full auto mode is a good place to keep it for the discerning, careful thinking photographer, the single mode for basic photography and then d nine and d twenty one for sports photography, those are my favorite modes on the camera. So if you have chosen a single point or a small group of points like d nine or the group, you could move those around left right up and down by using the multi selector on the back of the camera, and if you want to reposition everything back in the center, would simply press the okay button. Of course, to do this, you need to make sure that that is unlocked, so that little collar around the switch needs to be in the unlocked position, and so moving that around is a nice little option. However, one of things you need to know is that the focusing points in the centre are typically a little bit more sensitive to light than one's off to the side. So let's, take a look at how the focusing system works on this particular camera because there's a lot of focusing points, and they're not all equal. Some of the focusing points are horizontal line sensors, which means that if a vertical line hits that focusing point, it doesn't understand what's going on. It needs to hit both of these beam splitters for it to understand what type of line and so it's specifically looking for a horizontal line that out of focus is broken, and then it knows how to focus the lens in order to go it's sharp a straight line through those sensors. Some sensors are on ly sensitive to vertical wides and so they're looking for verticals and so you have to be aware of what type of sensors you have on the camera so here's, what you have on the cameras you have some that are sensitive with lenses that are two point eight or faster and there's not a lot of lenses that are two point eight or faster there a lot of the pro lenses they're there. There are some lenses that are gonna be at f four and have a vertical line censor. It gets a little complicated in here, folks. Now my favorite type of sensor is one that works with f five six lenses, which is the entire lineup of nikon lenses and across type sensor works with both vertical and horizontal lines. So what we have working in the d seven fifty is as follows. All of the focusing points are sensitive at f five six however it's on ly the group in the middle that are cross type sensors all the ones off on the left and the right hand side are horizontal line sensor detectors. If you were to mount, say a one point four converter or one point seven converter on some of the lenses, you might end up at an aperture between five six and f ate, in which case it's going to reduce the number of sensors that are going to be able to pick up auto focus information so it's just basically pulling in tighter and closer to the middle. And if you were to take, say, a five hundred millimeter lands that's, an f four mounted two times converter on it, it becomes an f eight lands. The center point is your only cross type focusing point, and the other focussing points are the horizontal line one, and so you've been reduced from fifty one down too much, much fewer number of points, depending on using these lenses that are much, much slower. Typically, we're talking about telephoto lenses that you are using a telly xander on. And so if you do want to switch focusing points, realized that if you are using those big lenses, you're going tohave limited functionality. So most of the time, the easiest way to remember this is just the center point is going to be the most sensitive to the different types of light that you were working with. So in summary on this you're going to hit the focusing mode button on the side of the camera. You're going to turn the back dial to choose where you want to focus, and you will choose thief front dial to how you want to focus, and so for general photography, I like to leave the camera in single, single a single point where it focuses and then stops for action. Photography. It depends a little bit on the action. But either the d nine or the g twenty one and the continuous servo auto focus mode. So a lot of different options in there play around with some of the different groupings in there. You may find something that works very well for the types of photography that you do.