Potential AF issues with Nikon D800?

Hi there,

I've been struggling to get sharp pictures with my D800 at wide apertures and I've been through many iterations at trying to figure out the problems. Trying to figure it out has gotten so bad that it has started to affect my mood around shooting at wider apertures.

At first I thought it was poor technique/too much focus/recompose at wide apertures, but even when trying to correct for that I found myself struggling and getting poor results when shooting at anything wider than f/5.6.

I had the camera body serviced by Nikon and I thought everything would have been fixed. I should have run some tests when I got the camera body back, but I didn't and just assumed that I could resume shooting without any issues anymore, but I'm still struggling. Shortly after I got it back I shot some light trails and shaked the camera a lot when doing so, not sure if I shouldn't have done that and if I could have messed up the AF sensor alignment once more when doing that.

Today I did a series of tests and with my Nikkor 24-70mm 2.8G ED I can't seem to be able to get a sharp picture at all at f/2.8 when using an off-center AF point. And that's shooting still life on a tripod with a timer, so camera shake is out of the question. When using the center AF point everything is good and I'm getting a sharp picture. I ran similar tests with my Sigma 105mm macro, and I seem to be getting better results, at its widest aperture of f/3. So maybe it could be something with the 24-70mm going on?

I also bought a lens calibration device to try and figure if my lenses just need calibration. I got the JJC ACA Autofocus Calibration Aid and followed the instructions from this video: . For both lenses the "0" is what seems most in-focus, which indicates that the lenses don't need to be calibrated. But what's strange to me is that with my 24-70mm I'm getting pictures that are not quite clear when viewed at 100%, even with lens calibration activated in Capture One. Maybe that's just the nature of trying to shoot a target like that with that lens? Like moire or something? I'm attaching pictures of what I'm getting. Even the JJC logo in the corner appears soft. And those calibration tests are done using the center AF point.

If anybody knows if it's normal to get poor AF performance when using an off-center AF point on a D800, that would really help. I'm trying to figure out if it's the way things are and I have to live with that, or if something seems wrong and I should have it get checked again. It's still on a service warranty from the last service date, so I could get it serviced again for free if it's really an issue that can be fixed.

Thanks so much in advance!

When you say "shaked the camera a lot", can you clarify on this?  

I was taking long exposure shots and moving the camera with my hands a whole lot during the exposures. Like flipping it from side to side as fast as I could, in the goal of getting interesting light trail patterns.

BLKFuel wrote: I was taking long exposure shots and moving the camera with my hands a whole lot during the exposures. Like flipping it from side to side as fast as I could, in the goal of getting interesting light trail patterns.

Movement is not the issue, stopping is the issue. Unless you were shaking the camera in the same manner you would a can of spray paint, or ketchup (i.e. mixing it up) then I would rather doubt you were able to impart any kinetic damage to the camera. That's assuming a relatively light lens, too, as the mount would have to withstand stresses as well. I could be wrong.

That said: lens calibration is per lens, not just the body. Your performance with one lens won't necessarily be the same as with another. Nor will image quality. For the photos you show, it looks to me like the focus plane is between 0.5 and 1, towards the camera. I'd move it back. But also keep in mind that your best focus isn't going to be wide open; it's usually 2-3 stops down. So, f/4 on the 24-70. How does it perform there?

Finally, you mention AF performance, but that typically means how quickly the camera can acquire focus. I don't think that's what you mean here? And when you say non-center, do you mean one of eleven crosshair focus points, or one of the 51 AF points? Because, don't. Stick to the eleven (or whatever it is).

Finally: you might want to get the lens evaluated. You may have a bad copy. It happens.

garyrhook wrote:

BLKFuel wrote: … lens calibration is per lens, not just the body.

The AF fine tuning is making sure that all three elements 
are working well to getter.

When I got the D850 — just like I did with my other 3 bodies
when I acquired them — it had to go through the fine tuning
procedures with all my 16 lenses… the limit is twenty.

BLKFuel wrote: I was taking long exposure shots and moving the camera with my hands a whole lot during the exposures. Like flipping it from side to side as fast as I could, in the goal of getting interesting light trail patterns.

Your camera will not be affected by that such movement.  It will take a lot more movement to mess the internals up.