There are rumors that the D810’s mirror and shutter motions are less damaging to image sharpness than those of the D800.
I thought it was worth running a test.
I put a Sigma 50mm f/1.4 DG on a D810, the camera in landscape orientation to an Arca Swiss Cube with a RRS L-bracket, and mounted the head to a sturdy set of RRS legs. Since the mirror and shutter in the D8x0 move up and down, and the tripod is stiffer in the vertical direction, the landscape orientation is the least vibration-prone way to orient the camera.
I aimed the camera at a slanted edge target illuminated with a Fotodiox 5500K LED flood. I set the self-timer to two seconds. I focused wide open, then set the aperture to f/5.6, the shutter speed to 1/400, the ISO to 100, and made an exposure. Then I turned down the flood (which doesn’t change color temperature as you reduce the light output) 1/3 of a stop, I made exposures with about the same mean sensor level in 1/3 stop intervals at shutter speeds down to 1/4 second.
Then I mounted a D800E and did the whole thing again.
I brought the raw files into Lightroom 5.6, set the white balance to Daylight, cropped to the target, and exported them as TIFF’s. I analysed the modulation transfer function (MTF) of all the images in Imatest using the horizontal edges.
There’s not much difference, but there’s a slight improvement with the D810. The vibration tends to increase with shutter speed. I fit logarithmic lines to the data so you can better judge that trend.
Mounting the cameras in portrait orientation and using the vertical edge give quite a different result:
The worst shutter speeds for both cameras are around 1/40 second, with the D810 again being slightly better. The difference between the two cameras is greater in this orientation, but in both cases the differences are small; this is not a reason to upgrade from a D800.