camera

In what way is the quality poor? Does it look like the camera is not focussing correctly? Are you holding the iPhone steady while taking pictures?

Brace the iPhone on something solid and take a few pix and see if that improves the quality, if it does then it is a motion problem. If that does not change the quality, it is most likely a focus issue and it would be good to take the iPhone to an Apple store genius bar and have the technicians check out the focus of the lens.

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There is nothing wrong with the camera or with 8.3. There is something wrong with your phone or the way you are using it. Maybe your case is blocking the focus sensor. Maybe the lens is dirty. Maybe there isn't enough light where you are trying to take your pictures. There are dozens of other possibilitie, but to narrow them down you need to describe the problem better.

Have you tried making a photo that is definitely steady, by supporting the iPhone on a solid surface? Did that make a difference?

Take the iPhone to an Apple store genius bar and have the technicians test it for you to see where the problem is occurring.