i don't shoot a lot of action, so i rarely run into the buffer on my d810 when shooting in continuous modes. i've been doing a lot of aerial shooting with the intervalometer and bracketing, which results in a steady flow of three frames every second for 10 to 15 minutes. no problems shooting at this rate.
what i do get a bit vexed by is waiting for 100gb or more of data to copy to the computer. i've been using any of a number of usb3 card readers and sandisk extreme pro SDXC-I cards (rated at 95 MB/s), as well as a bunch of sandisk extreme pro compactflash cards (rated at 160 MB/s). even though the D810 does not support the newer SDCX-II standard, i figured i'd try a newer extreme pro SDXC-II card, rated at 280 MB/s. of course, i was highly skeptical of those numbers since the basic memory technology is likely not much different than the others, and we all know interface specs are not always the limiting factor.
the results are surprising.
time to buffer clear after shooting a sequence on C-H (fully manual) of a fixed scene:
sandisk extreme pro SD-XC-II 22 seconds
sandisk extreme pro SD-XC-I 11 seconds
sandisk extreme pro CF 9 seconds
i'm not surprised that the CF is fastest - that matches other anecdotal evidence, and it's the fastest "supported" card type in the camera. but it's odd that the XC-II card wouldn't simply operate as an XC-I card and match that speed. twice as slow is a big difference.
copying the files to the computer is a different story.
sandisk extreme pro SD-XC-II : 172 MB/s
sandisk extreme pro SD-XC-I : 88 MB/s
sandisk extreme pro CF : 118 MB/s
so the CF is a good compromise, but the XC-II is by far the fastest in transferring to the computer, and by far the slowest in the camera. since i so rarely run into buffer limitations on the camera, i may switch to the "faster" cards, saving 5 or so minutes in a big download.
i wonder if the same poor in camera write performance will occur with other brands of XC-II cards?
