Nikon D3400 Autofocus
There are a couple of occasions when you might want to use manual. If, for example, you are shooting video and you have somebody who is fairly static, then I would recommend that you first of all use autofocus to ensure that the subject is sharp, and then switch it over to manual. That is just to prevent the possibility of, when the subject moves in or out of the frame or in and out of focus, it stops the camera trying to track. The other time might be if I am shooting landscapes. Now, again, I might well use the cameras autofocus system in order to make sure that I have everything in focus and then switch it off. That is really just to ensure that whilst I am either setting up or composing or while I am actually taking the picture itself which, remember, could be on quite a long shutter speed for 5 perhaps 10 seconds (perhaps more if it is a night-time shot) that the camera will not be distracted by something moving across the frame. It is a safeguard. The camera should not be distracted, but it is to ensure that nothing untoward does happen it is worth sometimes switching over to manual focus.
When you are in manual focus and you are looking through the viewfinder you have an option to help you here, which is called the rangefinder, and if you go into the menu and you go into the SETUP MENU then about halfway down just below BUTTONS you have an option for rangefinder. You also have the option below that to ensure that the MANUAL FOCUS RING is on, which of course is what you want. You switch that on when you are looking through the semi-automatic settings which are A, S and P, and you are looking through the viewfinder. You will see that there is a levels gauge at the bottom and it will move and will help you to discern when the subject that you are looking at is sharp. When it is sharp there will be a little green dot in the bottom left hand of the frame. When you are in MANUAL MODE that gauge is not there. It is an exposure levels gauge but the green dot will still appear when the subject is sharp. You do not get that when you are looking through the back screen and you are on manual. When you are looking through the back screen in MANUAL MODE, the best thing to do is to use the magnifying glass to magnify the image that you are looking at and so work on manually focusing by getting what you are looking at and what you are trying to focus on as large as possible on the back screen and that is fairly easily done through the magnifying glass + to go in and you can use the magnifying – to come back out again.
However in most cases, you will want to use the Nikon D3400 autofocus systems. The Nikon D3400 has two autofocus systems. The system that operates through the viewfinder is called PHASE DETECTION what that means essentially is that the beam that comes in through the lens is split and bounces around the back of the camera onto the sensor and at that point the camera tries to join the two images together again and in doing so it work out the length for the lens. It is very quick it is quite accurate and it is much quicker and far more accurate than the naked eye. For Liveview, it does not have the opportunity to split the beam coming through because the light goes straight through to the back of the camera. So the system used here is called CONTRAST DETECTION. Now actually this is pretty good too, because it gets right down to individual pixels where it can detect a contrast between different shades. However it can also be quite easily confused and that is more often than not when the illustrative light comes on here just to help the camera get a better idea of what it is looking at so that it can focus more accurately.
The Nikon D3400 DSLR camera essentially splits the focusing function, or the D3400 autofocus function, into two. It splits it into FOCUS MODE which essentially allows you to tell the camera whether the subject is static or moving, and then it also splits it into AUTO FOCUS AREA MODE, When you can tell the D3400 which part of the frame, or how much of the frame, the camera should be scanning in order to focus on the subject. That changes depending on whether you are looking through the viewfinder or whether you are looking through the back screen.
So lets take a look at them. Now, in this instance we are looking through the viewfinder. Of course, you can go in to the SHOOTING MENU and find FOCUS MODE and AREA FOCUS MODE on the back screen here, and make the changes accordingly, but that would be very complicated when you are trying to shoot things live, so fortunately they are on the back screen with the i button. So if I just come out of that and press ithen I will find them on the bottom line. The very bottom left is the FOCUSING MODE, so if we go into that one you find there are three options outside of manual. The three options are SINGLE SERVO which basically means that when you press the shutter button the camera will focus and it will remain focused until you either take your finger off the shutter button or you completely take the picture by pressing it all the way down. That can be quite useful because if you focus on the subject in the middle of your frame and yet you do not want the subject in the middle then you can move the camera so that the subject is off to one side and take the picture and the subject will still be sharp. The other option is AF-C which is CONTINUOUS. That is for things which are moving around, so again if you press the shutter button halfway down then you focus on the subject and if the subject moves then the focus will try to keep up with the subject and keep the subject in focus before you press the shutter. The third one is called AF – AUTO and that is kind of a mixture between the two. If your subject is static then it will just focus as if it is static and if your subject moves around it will effectively move on to continuous. However I do not recommend that last option because it is the Nikon D3400 making this decision, not you. I think you should make the decision so I would recommend that you either stick to single or continuous when you are looking through the viewfinder because you then have control over how the autofocus is working.
When you are looking through the back view screen there are two choices for this D3400 autofocus. They are SINGLE SERVO and FULL-TIME SERVO. Single servo just focuses when you press the shutter button, and is ideal for static subjects. Full-time servo will try continually to focus. Now this is quite interesting because unlike with looking through the viewfinder, when you have to keep the button pressed down, here it has a little green square on it and whatever is in the square the camera will attempt to keep in focus. That could be quite useful for when you are shooting video, for example, because it will try to keep whatever the subject is in the middle of the screen in focus. However it is quite slow and it does have to search sometimes, so it can be quite distracting. It is not as immediate or quick as you would hope and if you are shooting video then I go back to my original point. If it was me, shoot on single or shoot on manual. But it is not too bad. It does try its best and if you are going to shoot video where frankly the moving in and out does not really matter, then it can be very useful because of course it maintains that subject in focus.
So now lets take a look at the AUTO FOCUS AREA MODES for both systems on the Nikon D3400 DSLR. So if we look at the viewfinder first then again we go into the i button and this option is right next to the auto focus mode. If we, when we are looking through the viewfinder, look at AUTO FOCUS SINGLE, then there are two options options. The first one is SINGLE POINT AF and you will see the diamond of 11 points which are the 11 autofocus points that the camera uses and when it is on single point it will select the one in the middle, initially, to focus on the subject – and that will flash when you press the shutter button. If you want to change the point to one of the other 11 points then use the multi-selector to move that focus point around the diamond. That can be quite useful, particularly if you are on a tripod or you can not move the camera easily, because it means that you can then select a different part of the picture, a different subject perhaps, to be the focus point and to be sharp. So that is quite useful.
The next one then we get on to is AUTO AREA AUTO FOCUS and that essentially means that the camera tries to do everything for you – so it will use those 11 points in the frame to try and select the subject that it thinks should be sharp and in focus. It will very often be the one that is closest to the camera and that can be useful when you are trying to shoot things and you are not entirely sure what it is you are looking at. One of the disadvantages, of course, of looking through the viewfinder is that your vision is quite restricted. So if there are lots of things moving around or there are lots of things in the frame and you are not really sure what should be sharp on what should not, then this option can be quite useful.
Lets come out of autofocus single and look at D3400 autofocus continuous and see what the options are for the auto focus area modes there when you are looking through the viewfinder, because they are different. You get two which are the same: you get the single point and you get the auto area focus but you get two others, which are actually pretty interesting. The first one is DYNAMIC AREA AUTO FOCUS. What that does is that it tries to predict where the subject is going in the frame, so in other words, if the subject is moving diagonally through the frame so it is not just crossing the frame as on a single focal plane, if you like, it is moving in or out then the camera will try to predict that by gauging the movement that it has been doing between the focal points. So if it is moving towards you then obviously one focal point will have it so it 10 feet away another may have it at 8 feet away so it will predict that by the time it gets to this focal point it should be 6 feet away and that is what it means by trying to dynamically predict where the subject is going to be and that can be quite useful for obvious reasons because it means that it is trying to predict the focal length and the sharpness for you which is quite useful. The other one is 3D TRACKING. Now 3d tracking kind of does the same thing in that it does try to predict where the subject is going to be but it also allows you to move the camera at the same time so this is very useful for panning because it means that the camera does not get distracted by the background it just focuses on what it thinks is the subject of the frame and that can be very useful. Also bear in mind this is through the viewfinder so it is the faster of the two autofocus systems and so as a consequence of that it could be useful for things like sport or action photography. Now lets take a look at the autofocus area modes through the Liveview screen which is the contrast detection system. The difference here is that it does not actually matter in terms of your D3400 autofocus mode whether you are on continuous or whether you are on single, because the options are both same. So if we go in here then you have four choices and the two choices which you are going to come across most frequently are WIDE and NORMAL. Now if you click on wide and accept that then when you come into the back frame here you will see that there is a red square in the middle of the frame. That is your focus point and if you press the shutter button down halfway then it will focus and turn green – if you have got the beep on it will go beep – and that is essentially the limit of what it does. Now you can move that square by using the multi-selector you can move it to the right or up and down or left and if you want to return it to the center quickly you just press the OK button and it will return to the center, but that is your focal point within that square so if you go back into the i button and then back into AF area mode then coming out of wide and going into normal you will see that it is pretty much the same but that square is a lot smaller. In other words you can be far more specific when you are trying to choose your focus point and of course in either of those two settings you can press the magnifying glass to go further into the picture just to see whether you are actually pin sharp or just to check really that you are focusing on that thing that you wanted to focus upon. So those are the two more normal ones, those are the ones that you are going to use probably most frequently.
The D3400 autofocus option to the right is called SUBJECT TRACKING AUTOFOCUS and in some ways it is very similar to DYNAMIC autofocus for the system that is used through the viewfinder. But please bear in mind that you are looking through the back screen here and this system is much slower. So whilst it will also try to predict where the subject is going in the frame, it is not going to be as quick and it is not going to be as efficient as when you do it through the viewfinder. Then finally, and this actually is very useful, is FACE PRIORITY AUTOFOCUS. Now this is useful because it will automatically focus on and prioritize faces. It will detect faces in the frame automatically it will focus on one and if there are more than one face and you want to go to the other one you just use a multi-selector to push that on to another face. It is a really useful option particularly of course when you are taking group shots etc and it means that you can choose who to focus on and and it can actually do it quite efficiently. It is quite impressive if there is no face in the frame it just returns really to the wide option in other words you get a square in the middle of the frame that you can move around the frame as you would if you were in wide or normal. So those are your autofocus options with this camera there is quite a variety. You should be able to take pretty much any picture really and the autofocus options here would be able to help you take better pictures in almost any discipline. I would say as a rule of thumb that for normal everyday pictures I would be on – when looking through the viewfinder – on autofocus single and probably on single point. However if I was again using the viewfinder to shoot on continuous and to shoot something a bit more like action or sport, I might well go into dynamic area AF or even 3d tracking. But I tend to favor dynamic area because I am just more comfortable with that. If we go into the Liveview options then I would again tend to favor shooting on AF SINGLE just because it just makes it a bit more a bit more straightforward for me and also I think AF FULL TIME on the back is not as fast as CONTINUOUS through the viewfinder but on single again and here on the back I would be tempted to shoot probably on normal. I would not tend to use subject tracking on the back screen because it is easier to shoot that kind of stuff through the viewfinder but what I would say is FACE PRIORITY, when you are shooting group shots through the backscreen, is excellent and is well worth experimenting with. So those are the autofocus settings. Bear in mind that in autofocus settings it will not actually let you take a picture until it deems the subject to be sharp and so that could slow you down on occasion if you’re not careful. Also remember though that if you are on manual focus, this camera has no such control and if you press the button it will take the picture even if it is not sharp, because it has no control over focus you are then responsible for the focus. If you press the button at the wrong time then I am afraid if it is soft then that is your fault.