D7100 Inconsistent autofocus. Backfocus / front-focus

Originally Posted by intihuatana

I just want to confirm this focus issue with the D7100. This week I upgraded from the D7000 to the D7100. As it turns out I got TWO different cameras from TWO different vendors by accident. SO Naturally the question is which one to keep and which to return?


My first instinct was to return the camera body with a much higher shutter count. But as it turns out, tests with the same lens (35mm 1.8 DX G) and the same focus settings showed one camera to be suffering from very bad focus issues! As noted both back and in front of the subject. But generally Backfocus was worse. At least now I know which camera to return. And also to note the auto focus in Live View is much better and consistent. This is a very odd thing and I wonder if the LV uses a different focus sensor?

The D7100 is a older camera so i hope this modern explanation is correct, AF in the viewfinder is phase detect which needs the image to be focused via reflection to the focus detector then and back to the viewfinder/sensor, this obviously leaves scope for adjustments to be made, if you are seeing back and front focus errors then something else is wrong it should only be one or the other.
Focusing in LV uses contrast and it focus more at the sensor rather than calculating adjustments so if you dont have a fault with your lens it should be correct every time.
Even a brand new camera can need AF fine tune and it can be different for each lens but once done on each the camera should remember it.

I have a d7100 and can get some good sharp focus when a numbers of lenses.. Maybe post some photos of your issue?

Originally Posted by mikeee

I have a d7100 and can get some good sharp focus when a numbers of lenses.. Maybe post some photos of your issue?

I have a refurbished D7100 that is the sharpest body of all my Nikons so am thinking the same as you.