Nikon D5100 Auto Focus damaged?

[torque6]

If you really wanna test if your AF point is damaged, why not shoot a chart - something 2D - instead of a 3D object like your toy? Shooting something 3D (like your toy) has many factors contributing to the fact why your pictures are not sharp (i.e. in focus). If you shoot a chart and there's blur, it is for certain that your camera is a dud. However, in most cases it is most likely not.

What I think is that you got confused understanding between AF points and DOF.

Let me take your example and based on your information, you shoot at f/2.8, FL of 50mm, a Nikon D5100 and 50cm away from the toy (close to minimum focusing distance), that should put your total DOF at ~1cm. So is your toy thinner than 1cm? I think most likely not, and so there will be "blur".

And because your camera focus on a particular point, does not mean that it focuses where you want it to be. An AF point is sometimes larger than the dot you see in your viewfinder, and sometimes it chooses a more "contrasty" area within the AF point to focus.

So the recap, your toy is wider than 1cm in width, added the fact that the AF point may get it wrong, the resulting image is what you get. If you really want everything to be nice and focused, I would do is what Raskae and many other suggested, to close down the lens to f/8 (total DOF of 3cm) or f/16 (total DOF of 6cm), focus dead centre on the toy and shoot.

Hope this helps. Cheers.

Ya, like what rask mentioned, the AF point even though the single focus was on the head, it focused on the numbers behind. So did about 15 shots at different light settings, to no avail. So just switch to AF area and got the shot I want, which is toy 's head sharp. That why i am confused, depth of field should be same, distance and light same. The AF should give me the same results, but it didn't.... so I presume AF - area on the Nikon d5100 is more accurate than the single focus point, even though the same points were used by 2 different focusing modes. At least if at F2.8 both pics blur I can still understand, then can stop down but one blur one sharp... .. sigh..

Also my image not so good. Should crop further so you guys can see the difference at 200% zoom. Major confusion man. lol. Want to ask for help on this forum but cannot illustrate properly also give headache for bros here.

I do toy shots with an OMD and I usually shoot 5.6 for better DOF. No need F8 due to crop factor.

I have no issues with OMD but Nikon ... sigh.

 

[Rashkae]

Ya, like what rask mentioned, the AF point even though the single focus was on the head, it focused on the numbers behind. So did about 15 shots at different light settings, to no avail. So just switch to AF area and got the shot I want, which is toy 's head sharp. That why i am confused, depth of field should be same, distance and light same. The AF should give me the same results, but it didn't.... so I presume AF - area on the Nikon d5100 is more accurate than the single focus point, even though the same points were used by 2 different focusing modes. At least if at F2.8 both pics blur I can still understand, then can stop down but one blur one sharp... .. sigh..

Also my image not so good. Should crop further so you guys can see the difference at 200% zoom. Major confusion man. lol. Want to ask for help on this forum but cannot illustrate properly also give headache for bros here.

I do toy shots with an OMD and I usually shoot 5.6 for better DOF. No need F8 due to crop factor.

I have no issues with OMD but Nikon ... sigh.

No, it's because the wide af focused on the wings, and the head happened to be in the same plane of focus. It was actually NOT more accurate, you just got lucky with what it selected.

 

[torque6]

No, it's because the wide af focused on the wings, and the head happened to be in the same plane of focus. It was actually NOT more accurate, you just got lucky with what it selected.

hmm, never thought of that. Yes, you are correct again. It did focus on the wings with the head in the same POF.

 

[felixcat8888]

You should retry it with AFA single and use F8 or smaller aperture to ascertain that your focus is correct