Over the last several months, there have been numerous reports of auto-focus problems with the D800/E. Thes problems are most commonly reported when trying to auto-focus on the left-most focus point. Reports indicate that while manual focus and AF using the Live-view (contrast detection) AF work fine, using the (phase detection)AF , through the viewfinder causes blurry images. This problem is most accute when using wide angle lenses, with wide open aprture, close-in. Based on these reports, I decided to try a test for myself to see if my camera had the problem. Indeed it had and I ended up returning it to Nikon for repair. The good news is that it looks like the repair worked. The report below shows how I did the testing and compares the before and after results.
Test set-up.
The above image shows the target positioning. They were positioned so that, at 24mm, they were approx 6-7 feet from the camera and aligned so that the left-right-center focus points exactly aligned with thte center of their respective target, without needing to rotate or reposition the camera.
The lenses I tested were;
24-70mm f/2.8. Set 24mm and f/2.8 (microfocus set to -10 using LensAlign)
14-24mm f/2.8. Set to 24mm and f/2.8 (Microfocus set to -5 using lens Align)
50mm f/1.8. Set to f/1.8 (after clibration only) (Microfocus set to +5 using lens Align)
The procedure was as follows:
Position the camera at the same height as the targets and aligned with the focus points. Make sure the camera is level
Set Auto-exposure, AF (single servo) remote shutter release
For each focus point, the following shots were taken:
1. Live view, manual focus (to get a reference)
2. Live View auto focus (to check OK)
3. Viewfinder auto focus (to test operation)
3 shots were taken for each mode. When using AF, the lens was de-focussed between shots to check consistency. Also, for the viewfinder mode, Mup was used to get the best quality possible.
This sequence was performed for the center, left and right focus points.
Here is an example of results, prior to calibration, for the 24-70mm, set to 24mm f/2.8:
Center, Lv, MF
Center, Lv, AF
Center, VF, AF
The above images show that there is good matching of focus performance in the center of the screen.
Left, Lv, MF
Left, Lv, AF
Left, VF, AF
The above images show how the VF AF is not creating a sharp image.
Right, Lv, MF
Right, Lv, AF
Right, VF, AF
The above images show there is also defocussing on the right side, but less than the left.
There were similar results for the 14-24mm (@24mm, f/2.8):
Center, Lv, MF
Center, Lv, AF
Center, VF, AF
Left, Lv, MF
Left, Lv, AF
Left, VF, AF
Even worse. And so was the right side:
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Based on these results, I sent the camera back to Nikon for recalibration. This took approx. 3 weeks and I was suspicious about whether the problem would be fixed or not.
After re-calibration, I got the folloing results:
24-70mm, @f/2.8, 24mm:
Left, before:
Left after:
Right before:
Right after:
Clearly a significant difference! Not perfect but probably good enough. Remember, these are 100% crops
For the 14-24mm, here are the results:
Left before:
Left after:
Right before:
Right after:
So far, things look good!
One thing I noticed, by taking three or more images, refocussing each time, there was some variation in focus on the 24-70mm. In contrast, the 14-24mm was consitenlty sharp, every time. Here are some resutls fro the 24-70mm
Left, VF, AF:
All were still better that before calibration but worth remebering if I ever actually use the left-most focus point (highly unlikely).
As further confirmation, I did a quick test on the left focus point for the 50mm f/1.8 set at f/1.8:
Left, Lv, MF
Left, Lv, AF
Left, VF, AF
Results were consistent over a range of shots, refocussed each time.