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D800E/D800 Live much better than viewfinder.

D

devildog

Guest
For the OP:

There are lots of good explanations of the difference btw viewfinder focusing and live view out there, but here's a quick redux.

When you focus 'through the viewfinder', light is diverted from the mirror-path into an autofocus unit, which functions by a method known as "Phase Detection" autofocus. It is much quicker than "Contrast Detection", which is what happens in live view.

The problem is that, since this AF mechanism is separate from the lens-to-sensor light path, the point at which it is focusing (ie: where it imagines the sensor-plane is) might actually be a different distance from the lens than the sensor actually is. The difference may be microscopic, but digital pixels have almost no physical depth (compared to film) an error of a few microns will degrade image quality.

There are a lot of potential fails-points and, given the tolerances of manufacture, individual lens-specific adjustments are needed to get the best match of where the sensor is to where the a AF unit *thinks* it is.

The same problem holds for manual focus. If the ground-glass is a few microns closer or further from the lens than the sensor is, the image will look perfectly focused, but not be. No amount of dioptering or anything else will change that. It requires physical adjustment by the manufacturer.

In reality, most cameras are pretty good on these fronts. Especially for cheaply mass-manufactured consumer electronic devices (which, sadly, is what they are). It's just that the mega-resolution of these cameras now highlights the smallest error. The margins have shrunk.

Ok, so what about live view? Well, when you use live view, you are literally taking the image off the sensor. So if looks in focus, it's in focus. There is no margin of error because the place that you are focusing on is the same place the picture is taken.

Using an image sensor to focus is different than use an AF unit. Focusing off the sensor uses "Contrast Detection", which literally detects contrast at the point of focus. Just like the human eye. When the desired point is 'in focus' the difference between lines and edges (ie: points of contrast) will be at their most clearly defined. That is while live view 'hunts' a bit back and forth to find the sweet spot. Just like we would.

The problem with CD focusing is that it's generally much slower than dedicated AF units. Most point and shoots use phase detection, as do all mirrorless cameras. Only Olympus seems to have created CD systems which are truly zippy.

For critical work, where it can be done, live view will always give a perfectly focused image. "Viewfinder" focusing, however, should be adjustable to the point where it is almost as good in almost all cases. If it can't be, go see your dealer/service center, because the camera is out-of-tolerance, which happens regularly.

Hope this helps.

Cheers,

- Nick
 
danielmoore

danielmoore

New member
Got my D800E back from Nikon this morning. Fixed. Using a 24-70G to start, AF Fine Tuning turned off, tested at random nearer range 2.5' to 5' where it failed previously, hits the same or better than I can using Live View. I'd call that a successful calibration. Left/Center/Right all work similarly. I suspect they're inundated presently, they had my camera at the shop for 8 business days.
For the curious, the invoice read the following:
-----------------------------------

RPR FOCUSSING MECHANISM
GRIP COVER
ADJ AUTO FOCUS OPERATION
ADJ MIRROR ANGLE
CKD BAYONET MOUNT
CKD BODY FLANGE BACK
CKD IMAGE TEST
CKD EXPOSURE
CLN IMAGE SENSOR
GENERAL CHECK AND CLEAN
--------------------------------------------

Of course it's a shame it arrived when new in this state and that it cost me money in shipping and insurance to get it where it should have been, but here it is dialed in nice and tight.
 
k-hawinkler

k-hawinkler

Well-known member
danielmoore said:
Got my D800E back from Nikon this morning. Fixed. Using a 24-70G to start, AF Fine Tuning turned off, tested at random nearer range 2.5' to 5' where it failed previously, hits the same or better than I can using Live View. I'd call that a successful calibration. Left/Center/Right all work similarly. I suspect they're inundated presently, they had my camera at the shop for 8 business days.
For the curious, the invoice read the following:
-----------------------------------

RPR FOCUSSING MECHANISM
GRIP COVER
ADJ AUTO FOCUS OPERATION
ADJ MIRROR ANGLE
CKD BAYONET MOUNT
CKD BODY FLANGE BACK
CKD IMAGE TEST
CKD EXPOSURE
CLN IMAGE SENSOR
GENERAL CHECK AND CLEAN
--------------------------------------------

Of course it's a shame it arrived when new in this state and that it cost me money in shipping and insurance to get it where it should have been, but here it is dialed in nice and tight.
Click to expand...


Upon closer examination it appears my D800E exhibits the well known left autofocus issue and the other issues you describe.

Question: Which Nikon service center did fix your camera?

Thanks, K-H.
 
k-hawinkler

k-hawinkler

Well-known member
danielmoore said:
Nikon - El Segundo, CA
Click to expand...

Thank you so much.
That's what I thought, based on where you live.
So, both Nikon Service Centers in CA and NY seem to be ready now to repair these problems, based on what one can read on various fora. That's good to know.

Thanks again. With best regards, K-H.
 
danielmoore

danielmoore

New member
Weighing in, DPReview has the flakiest crowd of any fora I yet encountered,IMHO. One of the key's to happiness is to avoid it.
 
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