Nikon D800 Contrast and Phase Detect Autofocus Testing
After reading several posts about the ‘left autofocus point’ problems of the Nikon D800, I decided to test my own camera to see if it needed repair. Thom Hogan outlined a test method in his July 16, 2012 post and I decided to follow that method to test my camera, with a change. Initially, I developed a test target as per Thom’s suggestion but it led to problems so I did a second round of testing with the classic Siemens star.
Some notes about the camera and test
- I have a camera purchased in Canada, it was very early in the release cycle so call it an ‘early run’ camera.
- I used two lenses for the test, the Nikkor 50mm f/1.8G and Nikkor 24-70 f/2.8.
- I have not made any changes to auto focus fine tune.
- I used a Really Right Stuff TVC-33 carbon fiber tripod and BH-55 ball head to hold the camera.
- All exposures shot in RAW, converted to jpg to display here but no sharpening, lens correction, etc. was added. I only changed white balance and exposure to more easily compare things. I also cropped to make comparison easier. Everything managed with Adobe Lightroom 4.
- The lenses did not have any filters installed.
- Camera had distortion control turned off.
- Shot at the widest aperture (f/1.8 for the 50mm and f/2.8 for the 24-70) and ISO 100. The 24-70mm was shot at 24mm.
- Camera was leveled using the built in leveling tool and a three-way hot shoe level.
- The camera (sensor plane) was about 6.5′ from the wall.
Test Results – 50mm f/1.8G
Top row is Live View manual focus, second row is Live View AF, and last two rows are viewfinder phase detect AF. The 50mm does show less detail in the left AF sensor. Note, bigger versions of these test images are below, this is just a summary.
Test Results – 24mm f/2.8G
The 24mm lens shows a much more severe left AF issue.
This is a tedious exercise to both shoot and post. I did it twice as my first test chart didn’t yield useful results. My D800 does suffer from the left autofocus problem when using phase detect autofocus with the two lenses I tested. It will need to go to Nikon to get repaired.
Here is my test setup, in case anyone is curious.
Here are the full test patterns and should be in the same order shown above.
If you want to download the test chart I used, you can do so here.