Thanks. I played around with this and I don’t think lens profiles or shutter speeds make a difference, but yes ISO speed really does, gradually decreasing from 100 until 12800 or so. The annoying thing is you actually have to set it to an ISO speed- if you are in auto ISO and the camera sets the ISO speed to 100 you get a much lower number (ie, if in c-raw+jpeg, 31 vs 55). Perhaps that’s something a firmware update can fix- it’s kinda bordering on false advertising.The max burst is only achievable with Iso 100 and shutter speed above 1/500s.
Focus cases set to shutter release priority and Raw files only.
And turn off the lens profiles and flicker detection.
I recall Bryan Carnathan tested the burst capacity of the 1DX2 when it came out (with a CFast card). It shot full 14fps for more than six minutes until he grew weary of holding in the shutter button and gave up: with a sufficiently fast card, the card size is your eventual burst limit.My 1DX2 never shows max buffer in the readout but it will in most cases beat what it shows.
Link: https://www.the-digital-picture.com/Reviews/Canon-EOS-1D-X-Mark-II.aspxThe DIgital Picture said:To test the Canon EOS-1D X Mark II's 14 fps drive mode and 170 RAW file CFast buffer depth, I configured the camera to use ISO 100, a 1/8000 shutter speed (no waiting for the shutter operation), a wide open aperture (no time lost due to aperture blades closing) and manual focus (no focus lock delay). The lens cap remained on (insuring a black file and the smallest file size) and a freshly-formatted fast memory card was loaded.
Using a Transcend CFast 2.0 Memory Card (CFX650 256GB with Max. Read/Write Speed: 510/370 MB/s), the 1D X Mark II captured an incredible 14 frames per second ... until I got bored holding the shutter release down over 6 minutes later! The 14 fps converts to 840 fpm and, in 6:01.35, I had an extremely impressive 5,068 RAW images on the CFast card. With this card installed, the camera never filled its buffer and there is no waiting required to review images just taken (this can be important, especially when the next shot may come at any moment).
Simple steps to get 51 shots in burst:I shoot in cRaw+JPEG and the camera always indicates a max burst of 31 shots- but the manual says I should get 55-56? This is even with a uhs-2 card (Sandisk). Are there certain settings that hamper the max burst?