Subject is too dark subject is too dark subject is too dark etc.

[Eyelight]

The lens I am using only has A and M as the options, yet if I have my camera set to A on the lens I can still disable auto-focus using the software. Maybe I am misreading you but what you said there doesn't sound right.

The lens you have can only be set to manual focus using the switch on the lens. Selecting MF in the AF Mode menu in the camera software will disable autofocus, but will not allow you to focus the lens using the focus ring if the lens switch is set to A.

Basically, the camera can override the autofocus on a lens with the M/A option, but cannot override the autofocus on a lens with an A option like the lens you are using.

 

[dr_eyehead]

The lens you have can only be set to manual focus using the switch on the lens. Selecting MF in the AF Mode menu in the camera software will disable autofocus, but will not allow you to focus the lens using the focus ring if the lens switch is set to A.

Basically, the camera can override the autofocus on a lens with the M/A option, but cannot override the autofocus on a lens with an A option like the lens you are using.

With my AF-S NIKKOR 18-55mm DX VR 1:3.5 -5.6 G II lens, the one that came with the camera, if I set the lens to A (as opposed to M) and then set the focus mode to MF in the menu that comes up when I press <i> it overrides the auto-focus.... BUT I can't actually adjust the manual focus. We're both right. Let's move on.

 

[PaulPosition]

My excuses, upon verification there is no option for Focus Priority/Release Priority on the d3000 series..

(Edit: Some obviously wrong crap removed so as not to further muddy the waters)

 

[nickt]

I just tried to take some snaps with the lens cap on in manual mode (F10, exp 1/80, iso=100, EV=0 in case it matters).
-When in auto-focus it wouldn't take a shot.
-When either the camera or the lens was set to manual it then snapped, both with the shutter release button on the camera and the remote.
-Didn't seem to display the 'subject is too dark' when I was taking the blank shots, but it did flicker on briefly a few times.

That all makes sense, so that is good. Shutter and aperture priority should work the same way.

Does it matter whether I turn the auto-focus off on the lens or the software?

yes, see eyelight's post

Could this be anything to do with the AE-L/AF-L function? I tried to use that the other day but can't seem to get the hang of it/not quite sure what it does. I've worked out how to set how it functions, ie. hold down or one click, but whenever I try to use it it just seems to do the opposite of what I think it's doing....

You don't have those focus/release priority modes that Paul mentioned.
If you messed with the ae/af lock, that could mess you up a bit. You can't fully do the 'back button focus technique' on the d3200. That is because there is no release priority menu setting. So if you change the behavior of the back button to 'AF-on' and then recompose, the shutter may not fire because the focus point is not satisfied. I would set that back to ae/af lock for now.

 

[dr_eyehead]

AF-C is for moving subjects, I think it allows the camera to refocus if the area it's focusing on goes out of focus, whereas with AF-A it will lock when it focuses. It says in the manual that in all three modes that can be chosen other than MF, ie. AF-Auto, AF-Single Servo and AF-Continuous Servo that

Shutter can only be released if camera is able to focus.

In the case of AF-S I am not sure whether that means it will still take the shot if the subject goes out of focus while it is 'focus locked' though.

 

[dr_eyehead]

If you messed with the ae/af lock, that could mess you up a bit. You can't fully do the 'back button focus technique' on the d3200. That is because there is no release priority menu setting. So if you change the behavior of the back button to 'AF-on' and then recompose, the shutter may not fire because the focus point is not satisfied. I would set that back to ae/af lock for now.

What do you mean by 'back button focus technique', do you mean focusing on something else and locking the focus? Are you saying that if I focus on something else, lock the focus and then point the camera at the intended subject it wont let me take the shot if the camera thinks it's out of focus?

 

[nickt]

What do you mean by 'back button focus technique', do you mean focusing on something else and locking the focus? Are you saying that if I focus on something else, lock the focus and then point the camera at the intended subject it wont let me take the shot if the camera thinks it's out of focus?

If you use that button at its default setting, you can focus on something with a half press of the shutter, hold that back button, recompose, and shoot while still holding the back button. Aside from that, there is a popular technique called Back Button Focus Tecnique (BBF technique for short). I thought that is what you were referring to.

That BBF technique is done by setting the ae/af button to AF ON in the menu. Then you focus with the ae/af back button, rather than the shutter button. You hold the back button down and you get continuous focus. Release the button and the focusing stops and you can recompose without holding any buttons. It wont work that way on your camera. You need to be in af-c (which you do have) AND you need to set up release priority (which you DO NOT have). So if you focus with the reconfigured back button on your camera, you will not be able to fire the shutter if you recompose if the focus point is not seeing focus.

 

[Eyelight]

In the case of AF-A I am not sure whether that means it will still take the shot if the subject goes out of focus while it is 'focus locked' though.

When the shutter release button is pressed half way, the lens focuses and stays locked until you press the button fully or remove your finger. Autofocus does not know if you move the camera, so even if it were focused 100' away, after it locks with button half pressed, you could point the camera at the ground and take an out of focused photo.

 

[dr_eyehead]

I like this back button method, just playing around with it now. It seems to work on my camera in M mode and auto mode at least anyway, and in both camera modes. Does this also lock the exposure if in auto? Seems like an easier way to work with the camera.

 

[PaulPosition]

Nope, not exposure, only focus. You can use half-press on the shutter for exposure lock.

 

[nickt]

When the shutter release button is pressed half way, the lens focuses and stays locked until you press the button fully or remove your finger. Autofocus does not know if you move the camera, so even if it were focused 100' away, after it locks with button half pressed, you could point the camera at the ground and take an out of focused photo.

Just to add to this.... The book leads you to believe af-a is the best of AF-S and AF-C, but it does not behave like AF-C if you move the camera round. It acts like AF-C in the moment of action. Like if a runner was heading right at you, AF-A would likely adjust focus right up to tripping the shutter, like AF-C would do. But otherwise it settles down after a brief steady lock and behaves like af-s, exactly like eyelight described here. Once it locks for a bit, it stays there and you can recompose if you keep the button half pressed.

 

[aroy]

If you are suspecting an add on to be the reason, the first thing you should do is to take it off.
Modern DSLR are controlled by a computer program, it is not omnipotent, and has its own logic as to what is right and what is not. Hence it is better to bypass the camera's cryptic logic while testing. Here are some tips on settings when camera refuses to fire.
. When in AF the camera will not fire if it thinks it is out of focus.
. Setting MF on the lens is the the only way to ensure manual focus.
. Setting the mode to "M" means that you set your own exposure parameters, and the camera will accept what ever you do.
. If the camera does not fire, then set the mode to "M" and the lense to M. If it does not fire then either the modes are not set to "M" or there is a camera fault.
. If VR is on, and your hand shakes (or has minor tremors) the camera will take a lot of time to fire. So while testing switch the VR off.