[Note: this post was extensively rewritten on 7/28. I made the measurements in the original post based on an erroneous understanding of how the EFCS controls on the D810 work., I me-shot all the images to produce what you now see here.]
One of the new features on the D810 is the electronic first curtain shutter (EFCS), which should in conjunction with raising the mirror well before the exposure, reduce vibration.
As I now realize, the EFCS controls on the S810 work quite differently from those on the Sony a7 and a7S. Like the Sonys, there’s a menu item to turn EFCS on and off on the D810. Unlike the Sonys, you don’t actually get EFCS until you set the drive mode to a particular setting. In the D810, that setting is “Mirror up”. (Having no mirror, the Sonys have so such setting.)
In the D810, mirror up drive mode works this way with live view off: pressing the shutter release for the first time raises the mirror. If EFCS has been invoked, the shutter opens. The second time you press the shutter release, the shutter fires — immediately if you have not set a shutter delay, and after 1, 2, or 3 seconds if you have.
With live view on, mirror up works a little differently. Pressing the shutter release does nothing but blank the LCD screen if EFCS has been selected — the mirror is already up and the shutter is open. If it hasn’t, the first press of the shutter release closes the shutter.
The worst part of the system is understanding it or explaining it. In practice, there is an advantage: EFCS can effectively the controlled without going into the menu system. I wish there were a way to control shutter delay the same way. Having an option to have shutter delay onl operate in mirror up mode would do the trick with no more buttons or dials on the camera.
I thought I’d see how much improvement EFCS made with a “normal” lens. I picked the Sigma 50mm f/1.4 DG. I mounted 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 shutter in the D810 moves 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 turned EFCS on. I set the shutter delay to 3 seconds. I focused wide open, then set the aperture to f/5.6, the shutter speed to 1/250, the ISO to 125, 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 turned EFCS off and did the whole thing again.
I converted the raw files to DNG with Adobe DNG Converter 184.108.40.206 beta, brought them into Lightroom 5.5, 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.
Here is MTF50:
There’s not much improvement with the EFCS except at shutter speeds between 1/80 and 1/50. Even there the improvement is slight.
Here’s the MTF30 data:
Pretty much the same story.