Autofocus Not Working

bruto

@reddawn

I keep learning new things even now, and while fiddling with
AF settings on my D3200 came across an interesting and, it seems, entirely undocumented phenomenon.

Ordinarily the camera is on what is known as "focus priority", which means that it will not shoot a picture unless it's focused.

However, if in the menu (I'm going by the D3200, but yours should be similar) you go to the "Buttons" subsection in setup, and "assign AEL -AFL button" item, you will find as one option "AF-ON". What this function does is to remove all AF operation from the shutter button. What it also does, without the manual telling us, is to switch the camera to shutter priority! In other words, if you aim the camera and press the shutter button, not only wont it auto focus, but it also will take a blurry picture.

Go into your menus and make sure somehow this setting did not get changed.

Edit to add: it appears the D5100 does have a separate setting for focus versus release (or shutter) priority, so that should be checked too.

ncgator75

Viewfinder not autofocusing---what a great site. Bruto your post allowed me to pin-point my exact problem. The Viewfinder mode does not autofocus most of the time. I have done everything suggested, and it still doesn't work. So now I have a camera more than 5 years old, and I need a suggestion on what I should do. I guess I could send into Nikon to have it fixed, but I don't know the cost to fix it. Even then I would have a working 5 year old camera. Or do I bite the bullet and buy a new/refurbished D5200/D5300 or a new D5500? Any suggestions?

bruto

One thing that might be worth trying is to get the camera cleaned. The phase detect AF uses a sensor and mirrors that can get dirty. If AF is working only intermittently, that is likely better than not at all, and suggests that either there's dirt or misalignment. As always, one thing to do is to make sure that the AF point is correctly aimed. I'm always accidentally moving it, and having to recenter it with the [OK] button.

WJShaheen

Thanks, Bruto. My D5300 had assign AE-AL set to AF-ON (makes sense, no?).

I set it to AE-L/AF-L and now when I press the shutter half-way it focuses!

Again, my thanks.
Bill in Arizona

Marilou

This forum has been a great help. Thank you so much!

bobble55

Just had this problem with my d5200 today, and after a bit of swearing noticed that the AE-l button was autofocusing ( with all my usual lenses ) went into the controls menu and sure enough ( for no reason that i know ) the ael button had been assigned to AF on, changed it to AE lock only and everything was back as it should be

bruto

Yes "AF-ON" seems rather a poor terminology for what it actually is, which is back button focusing. Many people (myself included) use and like that feature, but it is, of course, something you need to be doing on purpose!

For those interested, I do recommend that you consider back button focusing, as it can be a very useful tool, especially in lower end cameras whose focusing options are not easily accessed from buttons, and especialy on the D3xxx family which do not allow you to select release priority in AFC mode. Tracking birds in flight with only focus priority can result in many misses as focus is briefly lost.

With AF-On, your lens focuses only when you push the back button. On some cameras, to make this action complete one may also have to turn off the shutter button AF separately (not needed on the D3200 and others), and for best results you must re-assign AE lock to the shutter button half press.

When this has been done (and once one has learned new shooting habits), one can then set AF to remain at AFC always. When you wish to focus and recompose, you simply let go of the back button, and recompose and shoot. When you wish to track motion, you hold the button. For complicated compositions and light, this setup decouples AE and AF and shooting. So, for example, when I was in Alaska dealing with very difficult light, I could auto focus on one object, spot meter on yet another, and then, holding down the shutter button, recompose and shoot on yet another, all without moving the center focus point. When back button focus is used, the priorities are as set when the button is down, but most cameras will revert to release priority when it is released (higher end cameras do not, and thus allow focus trapping, a whole other subject, but lower end ones do not).

When one first starts using back button focus, it will take a while to remember to actuate the focus and you'll get some blurred shots. After a while it becomes such a habit that now when using other cameras I push the back button whether it's needed or not.

I throw this in just as a kind of teaser for those who wish to do a little AF adventuring. In the mean time, though, I'm glad that the problem has been resolved without anything needing replacement or repair!

scoutsolitario

I have a Nikon D5100 and I used normally for youth football and cheerleading’s activities photographs. In the process, I use the 18-55 mm lens in A and VR ‘On’ mode - it works fine; however, when I use the 55-200 mm lens having the same settings I get blurry pictures that are not noticeable until I download it to the PC. I normally take an average of 1500 pictures per events that lapses a day or two each.

The past weekend we had a national cheers competition and 85% on my photos were very blurry.

Any recommendations or suggestions on specific settings I should be working on to fix this problem?

I has just joined the group and read many of the comments and suggestions; but since I am dedicating my hobby for an activity that involves constant and fast moving actions; perhaps some suggestions will help me find a fix to these problems. I should also mention that I have a Nikon D40 and had no problem until I switched to the D5100 series.

I thank you in advance for any suggestions.

bruto

My suggestion would be first to determine what AF area mode you are using, and also to check the pictures carefully to see if some areas are in focus, other than those you aimed at.

The longer lens will be less forgiving of focus errors because its depth of field is shallow.

Check your AF area mode, and make sure it's either on single point or dynamic area mode, preferably a small area to start with. Now also make sure that your focus point is centered, or where you want it (push the OK button to center it), because it is very easy accidentally to bump it off center. If you're always following action, you might do better to switch to AFC rather than AFA. AFA will go to AFC when it detects subject motion, but it may take a little moment before it starts.

For this kind of thing, never use Auto Area focus. It will attempt to fix on what the camera thinks is the closest subject, and you can't trust that. Find the cheerleader you want to be the center of attention, and focus on her eyes.

You should get some photographs into a computer and do some pixel peeping on the blurred ones to see if the AF has been hitting the wrong spot. If there's nothing at all in focus make sure the lens itself is not at fault. Try shooting at varied distances and make sure you can see or hear the lens changing focus. Switch the AF/M switch back and forth a couple of times to make sure it's engaging properly. I know my 55-300 lens sometimes seems to forget that it's supposed to be on AF, and switching wakes it up.

Also, remember that even with VR, a long lens will require a pretty fast shutter speed to avoid blur and that VR will not freeze motion of people. To stop motion reliably you'll need probably a minimum of 1/250 shutter speed, and more would be nice. You may have to crank up your ISO pretty high if the competition is not very well lit.