The in body Vibration Reduction (VR) turned on in combination with the Mechanical Shutter shakes the image sensor resulting blurry images that look like 10MP instead of 24MP. More exactly the Mechanical Front-Curtain Shutter shakes the sensor at shutter speeds between 1/30s and 1/250s, but only when the VR is turned on. The worst being at 1/100s, 1/125s and 1/160s. The following tests are made at 1/125s.
This problem does not appear on a Sony a7iii, which is a similar Mirrorless camera with similar specs and price. Scroll down to see the Sony a7iii test.
1st Test – Mechanical Shutter + VR-on vs Electronic Front-Curtain Shutter + VR-on
Using the Electronic Front-Curtain Shutter or Silent Shutter does not shake the sensor while the VR is on, resulting a sharp image.
The two images from the 1st test:
2nd Test – Mechanical Shutter + VR-on vs Mechanical Shutter + VR-off
VR-off locks the sensor and the Mechanical Shutter cannot shake the sensor resulting a sharp image.
The two images from the 2nd test:
3rd Test – Mechanical + VR-off (sharp image downscaled to 10MP then upscaled to 24MP resulting a loss of quality and sharpness) vs Mechanical + VR-on (at original 24MP)
3a – The difference between the original 24MP and the upscaled 24MP from the downscaled 10MP. Clearly a loss of quality and sharpness.
3b – The difference between the upscaled 24MP from the downscaled 10MP and the original 24MP Mechanical + VR-on
The 24MP upscaled image looks better than the original 24MP with Mechanical Shutter + VR-on.
How the test was made:
For testing, the camera settings can be found in the image EXIF using Nikon ViewNX-i. All images are made with these settings:
-Focal Length: 28mm
-Shutter Speed: 1/125s
-Focus: AF-S PinPoint
-Image quality: JPEG fine* at 24MP (best quality)
-Picture Control: Standard
-Color Space: sRGB
-Active D-Lighting: Off
-Long Exposure NR: Off
-High ISO NR: Off
-Vignette Control: Normal
-Diffraction Compensation: On
-Auto Distortion Control: On
-Flicker reduction shooting: On
The light must be continuous and good enough for ISO 100.