# D3100 autofocus only works in live view



## eharmon11 (Dec 10, 2011)

I just discovered that the autofocus works in live view, because I had been thinking it wasn't working at all! I have a D3100, paired with an AF-S lens.  No matter what mode of focus, AF-S, AF-C, AF-A, if the LENS is on Autofocus the camera's shutter will NOT release.  BUT....if the camera is in live view it DOES.  weird much?  when I have it through the view finder and I put the camera fully on Auto pilot, it will sometimes take the picture, it just won't be in focus. Even with the lens on auto focus.  is my camera possessed? The contacts are clean, it has an SD card in it.  Its a brand new camera. But my buddys D3000 does the same thing with my lens.  Any suggestions on what could be wrong.  I saw someone elses post regarding a similar issue I think, so I'm guessing its not even my lens.  Please help if you have any ideas!!!!! Also, it takes forever to focus, not a "split second" as advertised.


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## KmH (Dec 10, 2011)

No, not weird at all. The D3100 has to use a different auto focus system when Live View is in operation, than the auto focus system it uses otherwise.

The default on most cameras for shutter release is focus-priority.

If focus has not been achieved, the shutter will not release. 

Pages 55-63 of the D3100 user's manual cover focus and the various focus permutations/options.

Note where it describes those situations where auto focus has limitations, like in low light, if background objects appear larger than the subject, if there are repeating geometrical shape or it's a busy scene that has a lot of detail in it.


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## eharmon11 (Dec 10, 2011)

Oh how interesting.  So the shutter priority is different in live view?  follow up question then....my buddy has a lens that will take  photos with the view finder, in manual mode.  Is it because his lens is a shorter zoom thus able to use light more effectively?  His is just the starter kit lense, 28-55 I think, and mine is 55-200.  Making the photos seem darker.  Do you suppose my camera is just not able to focus with that little of light or something?

It seems odd that I can't use this lens in all situations.


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