My D800 focus woes

Started Apr 8, 2012 | Discussions thread
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CaptainObvious
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My D800 focus woes
Apr 8, 2012

I'm using a 50mm 1.8d lens. I've dialed in -4 on the lens.

Pics are sharp using the center focus point for targets that are about 8 feet away in sunlight. Using side focus points, the image is WAY out of focus... not close, not usable by any stretch of the imagination. I guess Nikon's target really was the 5D M2, in that they increased the resolution, but only gave us a useful center point. Cue laughter...

I seemed to be getting inconsistent results for subjects further than 20 feet away. I was aiming at various things in and around my yard, yet it seemed that most of the time focus would lock without even adjusting, despite the fact that the various targets were differing distances. So I switched to manual focus to use the rangefinder function. I was on my deck pointing down to the yard, and NOT touching the focus ring. Panning the camera in and out several times, I confirmed that the camera considers everything from 30' to about 60' to be properly focused. Is that normal? I think DOF should be a total of 12' for 50mm f1.8 with a 30' subject, or 30' with a 45' subject. But should the camera truly consider everything in the DOF truly focused? I did the same test with the right-most focus point, and the range considered to be focused was cut by half... despite using a less accurate sensor. Hmmm.

Now, why am I doing all this? Because only 1 out of 4 REAL pics I take are in focus, despite using single-point. The image quality is outstanding when the photos are focused... but it is a rarity to get a tack sharp eye with this thing.

Is this just a case of the 50 1.8d being so miserably soft wide open that it is just too hard for PDAF to focus with?

FYI, I had a 50 1.8g that I returned because it required a +18 focus adjustment. I wish I would have tested with the other focus points to see if I saw the same variation.

And yes, for my focus adjustments, I've used a tripod, timer mode, with 2s shutter delay also so not even the mirror is having an impact. The focus is always off without the -4 adjustment. Sometimes it rivals live-view with -4 with a 8' target in good light, so I think I've got as good a setting as possible.

This is frustrating. I don't know if my problems would be solved with a smaller aperture, sharper lens, or if the camera is just going to be unreliable for autofocus. My vision isn't good enough for manual focus. I wanted the camera for indoor use. The high ISO means nothing if I lose over a stop by being forced into an f2.8 lens so it can autofocus. I could have bought MFT with a Panny f1.7 20mm and ended up with a similar result for indoor use.

Canon EOS 5D Nikon D800
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