Focus modes

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Rasmus

Senior Member
Hi all

I'm still struggling a bit with my d7k. The camera works fine, no backfocus etc. But i often get less than sharp images, especially of moving objects. I'm guessing it's because of the focus settings.

I have the camera in AF-A and 3d focus. The reason for using 3D is that i want the focus to lock on something(face usually), and then keep that focus even if the person, or animal, moves around.

It seems like the camera struggles to do this, with my current settings. How do you setup up your cameras to accomplish this? IE half-press the shutter to lock the focus point on a face, and then either the person moves, or i recompose to get a shot of the entire person.

I'm fairly sure the problem lies in these settings, not in shutter speed, aperture or iso. I attached an example of a very un-sharp images. D7K_4187.NEF.jpg
 
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gqtuazon

Gear Head
Try AF-C, 9 or 11 point AF. Smaller aperture lenses are also slow to focus so try other lenses and practice a lot. Running dogs are pretty hard to capture unless you prefocus and set it to f8 to give you more DOF and increase your shutter speed above 1/640.
 
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Rasmus

Senior Member
Sv: Focus modes

Part of the problem is that focus doesn't update when the subject moves. I would have thought that's exactly what 3d mode is for?

Can I do it with af lock? I would prefer having it lock focus with the shutter

Sendt fra min GT-I9300 med Tapatalk2
 
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nickt

Senior Member
If you have not already, you can set your camera to display the focus point used when you play back the images in camera. This is very helpful as you experiment with various AF settings. You can also see this info using the Nikon software on your computer after you download the images. I suspect that in this case, the focus point is on the dog, but since he was coming right at you, the camera did not respond to that.
I'm still sketchy on 3d mode and have not played with it enough. AF-C might respond better. Set focus menu item a3 to 'off'. Menu a3 introduces a delay into continuous focus. Menu a1 will determine if the shutter will release regardless of focus in AF-C. I would try release priority if you find you can't get the shot with focus priority.
You could try short a burst of shots too with a1 set to release and a3 off and see if you catch a better focus.
 
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nickt

Senior Member
Just to further babble on.... I think I finally have this straight in my head....

AF-S, AF-C, and AF-A are servo modes. They decide how the camera will control the focus motor in response to the focus point data it is receiving. Basically it is the decision of will it focus once and stay put (AF-S) or will it refocus as needed (AF-C) during the half press. AF-A will try to determine which of those two servo modes is more appropriate. AF-S and AF-C can be individually tweaked in the focus menu for release or focus priority.

The AF Area Modes (Single Point-AF, Dynamic Area-AF, 3D-Tracking, and Auto-Area AF) are methods for acquiring and/or maintaining a focus point. Some are better for action than others and some are unavailable if AF-S servo mode is selected. The details of each area mode are in the manual. These modes do not directly determine what the focus motor will do with the focus point. AF-S or AF-C servo mode will determine if it is a one time focus event or if focus will be updated.

So to the OP, try various AF area modes to see what best puts the point on the moving subject. Single point may be the fastest if he is heading right at you or you are panning. Whatever mode you choose to acquire a focus point, stick to AF-C servo mode for action shots as it might make the decision to refocus quicker than AF-A. Be sure to set a3 to off for the quickest response. A3 'on' might be helpful if you are following a sports player and distractions like back of someone's head might enter the frame. In that case, the delay from a3 will ignore a brief intrusion into the frame.
 
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aced19

Senior Member
Rasmus,
I shoot a lot of sports and I would set my camera to shoot anything moving to these settings.
Servo mode AF-C.
39 pt dynamic area setting (I've tried the single, 9 and 21 pt. But the 39 gave me the sharpest pics.).
Also set your AE-L/AF-L button to AF-ON.
You set your AE-L/AF-L button this way to work with the AF-C.
When set up like this, you use your thumb to press and hold the AE-L/AF-L button and your index finger on the shutter(not pressed half down).
By pressing and holding the AE-L/AF-L button it will make the lens continually focus on your subject, all you have to do is push the shutter when
you want to take a picture. It's the same as holding the shutter half way down but sometimes its hard to do that for a long period of time.




 
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